USB “OTG” stands for USB “On The Go”. USB On-The-Go is a specification of the USB protocol that allows traditionally slave devices such as smart phones, to act as master devices or host systems (e.g. personal computers) when connected to either other slave devices such as digital cameras and printers; or peripherals such: USB storage disks or human interface devices (e.g. keyboard and mouse).
USB plug classifications.
There are a myriad different types and generations of USB cables available on the market today. However most obey the convention of having two different plug-socket configuration in each class specification. A type-A plug and socket for connecting with the host system (a.k.a. “A” device), and a type-B plug and socket for connecting with the slave (or “B”) device. A standard USB cable will have one male type-A plug and one male type-B plug. A USB OTG cable differs from a standard USB cable in only one significant way. The standard USB type-A plug is replaced with either a USB Mini type-A or USB Micro type-A variant. That’s it.
For example to connect a generic modern printer to a smart phone with a USB Micro type-AB socket. One would need a male USB Micro type-A to male USB type-B cable. The replacement of the USB type-A with a USB Micro type-A is what makes it an “On The Go” configuration. This means you don’t need a traditional PC to use the printer. You can connect directly with and use the mobile device to send the files to the printer in it’s stead.
image taken from wikipedia.org
Limitations of the USB OTG specification.
A device with OTG enabled capabilities unfortunately can not act as a general purposes host system with the same peripheral compatibilities as a personal computer. Instead they are given a Targeted Peripheral List (TPL) from their manufacturers. This is a rather limited list of general peripherals designed to work with the particular device for it’s expected use cases. This is because these devices will have limitations on them such as power output or limited supported protocols.
Unfortunately, as I see it; with the innumerable amounts of devices (smart phones, tablets, etcetera) and peripherals (with various protocols and power draws) on the market today: the best way to find out whether or not a peripheral is compatible with your particular device – is to just plug it in and see. This is also true for finding out whether or not your device supports the USB OTG functionality in general. Some might not.
I tested a couple of smart phones I had on hand, and of the four I had, only one actually supported OTG functionality. The other three simply didn’t register the peripherals (including a basic USB thumb stick) plugged into them. These were: (2011) Samsung GT-I5500, (2012) HTC Chacha, (2015) Huawei GRA-L09, and (2018) Blackview A30. Of them only the Huawei GRA-L09 worked with my OTG cable. It performed perfectly with the wireless USB keyboard-mouse combo, and the thumb drive I tested with. The Huawei even allowed connections to the other smartphones (using a Micro type-A to Micro type-B cable). It could charge the other devices, register on their end as connected to a host, but not allow access to their filesystem like a PC would allow. This last thing could be a software limitation, that will require some further tinkering to work; or possibly using some kind of third-party file browser or peripheral manager. Long story short, when it comes to compatibility: your mileage may vary.
Creating a USB Micro OTG cable.
The USB OTG specification was originally created for use with mobile devices that utilised the USB Mini standard, and later updated to include the USB Micro standard. We will create an OTG cable by modifying a Micro type-B plug to a Micro type-A plug. Then using it to create a male USB Micro type-A to USB (full size) type-A socket. This is to connect basic low power USB peripherals such as storage drives or a wireless mouse and keyboard combo. Which is my particular use case. However it should be stated that the same modifications can be made to a USB Mini type-B plug to turn it into an OTG enabled Mini type-A plug.
To create a basic USB Micro OTG cable is actually rather simple. All you essentially need to do is short the ID pin (pin 4) on the USB Micro type-B plug to ground (pin 5). This procedure effectively (i.e. electrically) turns the Micro type-B plug into a Micro type-A plug.
Unfortunately in my case, my kit USB Micro plugs only came with 4 soldering pads (for the power and data lines). It was missing a solder pad for the ID pin. This meant I couldn’t just run a small jumper from the ID pad to the ground pad. I instead had to access the ID pin directly. On one hand this makes creating the OTG cables that require some resistance value between the ID and the ground pin significantly harder. Due to no room for the resistor. However if you intend to just create a basic cable, then this method of just bridging the ID and ground pin can be useful for salvaged USB Micro plugs who in all likelihood won’t have an ID solder pad.
With this in mind, I disassembled a kit USB Micro type-B plug. Next I scraped the covering plastic on pin 4 and 5, then soldered a bridge across them. I removed the plastic to create space and headroom for the solder bridge. Otherwise, I may be unable to slide the plug head (with it’s plastic inner lining) back on. Space constraints need to be paid attention to. Reassembled the plug. Then tested for continuity using a multimeter and a USB Micro type-B socket breakout board. Id est making sure that pin 4 is grounded, and that the solder bridge wasn’t coming off.
Please note, there are other methods for creating OTG cables that involve running a specific resistor across the ID and ground pins for certain devices to work, or to enable the host and/or peripheral device to draw power from an external power source. However I am omitting them, for brevity. This is a quick guide to build a basic DIY OTG cable.
I decided to make the pictured OTG cable modular using breadboard jumper cables. The reason for this is because I intend to mix and match various plug and socket ends to create different types of cables. However, I would recommend making a more fixed and permanent cable for actual real-world use.
Modular OTG cable example
Tooling and material example
Disassembly and modification of a USB Micro type-B plug
Modular male Micro type-A to female USB type-A OTG cable in use
Modular male Micro type-A to male Micro type-B OTG cable in use
#0008: Repair and Analysis of USB Micro type-B cables
If you are anything like me you probably have a sizeable collection of broken Micro USB cables neatly spooled onto a hook, or into a bag. Alternatively, you may even have them tangled into a rat king in a box or drawer somewhere … that is if you are a barbarian. You know who you are. So in an effort to lighten my ‘Spares & Repairs’ bin short of throwing things away (perish the thought!). I though it’d be good to repair a few. I know crazy right?
How and where do Micro USB cables typically break?
In order to repair something, we must first asses the damage. Where is it and how much is there? Well, with regards to the generic male USB 2.0 type-A plug to male USB Micro type-B plug cable: the damage is predominantly focused in the male Micro USB plug. Please note I will be using the term ‘Micro USB plug’ as shorthand for ‘male USB Micro type-B plug’ throughout this article.
Initially, I used to get annoyed whenever a cable broke and rebuke the relatively delicate Micro USB plug as poorly designed. However, on reflection it is actually rather good that the weakest point in the pairing of the plug and socket: is in the plug and not the socket. Especially since after such incidents, the device socket tends to end up with little if no damage at all.
This is assuming that the majority of accidental breakages happen under certain conditions. These include: firstly, that the Micro USB plug is inserted into it’s respective socket on the device at the time. Whereupon it comes into acute mechanical stress by something akin a sudden impact (e.g. from a fall); or by a particularly vicious cable snag. This stress consequentially puts a lot of pressure on the connection between cable and device. Which in most cases causes the cable’s plug to give in before the device’s socket. Sometimes both are damaged if the impact is strong enough. However in a more typical scenario the plug breaks first, and in such a way as to leave the socket relatively unharmed.
Although my knee-jerk reaction is irritation whenever I perceive something as genuinely designed to break; I think in hindsight it is better that the cable’s plug is designed to break before the device’s socket. Since the cable is far easier (and consequently cheaper) to either replace or repair than the device would be. After doing some research, it seems that this is a conscious design decision (citation needed) and not one based on anti-consumer avarice, which (as a long time purchaser of consumer grade electronics) is the assumption that I have been conditioned to have in these types of scenarios. “Think Different”, Think Planned Obsolescence.
In this case, it is actually an iterative improvement on it’s predecessor: the Mini USB standard. Which suffered from port damage due to the shape and structural strength of the male plug, coupled with the fact that the retention and locking mechanism is located within the socket in the Mini USB standard. Whereas within the Micro USB standard, all such fragile and consequently breakable parts are located cable side. Having said that though, it still sucks when useful tools break so let’s try fixing them.
USB Mini socket
Structure of a male USB Micro type-B to male USB 2.0 type-A cable.
The male USB Micro type-B (or Micro USB) plug on average has typically four or five pads at it’s cable side and five interface pins that mate with it’s counterpart female socket. Please refer to the pin out diagram.
USB type-A: Pin | Name | Wire Colour | Function 1 | VBUS | red | +5 volts supply 2 | D- | white | Data- 3 | D+ | green | Data+ 4 | GND | black | Ground
USB Micro type-B: Pin | Name | Wire Colour | Function 1 | VBUS | red | +5 volts supply 2 | D- | white | Data- 3 | D+ | green | Data+ 4 | ID | no wire | ID pin for OTG functionality 5 | GND | black | Ground
Its simple really, pins 1 and 5 are used for power. Pin 1 supplies the +5 volts and pin 5 is it’s ground. Pins 2 and 3 are used for transmitting the data signals for communication. And finally, pin 4 is an identification pin, which is used for USB ‘On The Go’ functionality. It essentially tells the device that it is connected to, whether or not it is to act as a host system or a slave device when communicating with the device on the other end of the cable.
Its a very similar setup with the male USB 2.0 type-A plug on the other side of this cable, except that it lacks an ID pin. Pin 1 is the V bus carrying +5 volts, pin 4 is the signal ground, and pins 2 and 3 are the negative and positive data pins respectively.
The reason the USB type-A plug lacks an ID pin is because any device that has a full sized female USB type-A port is already assumed to be the host system. Finding a peripheral device such as a keyboard (with the exception of USB pass-through), or mouse, or even a smart phone with a full sized female USB type-A socket is non-standard; as are the male USB type-A to male USB type-A cables needed for them.
The wikipedia.org article (“USB hardware”) mentioning this cable labels it as ‘proprietary, hazardous’. If I were to guess as to why that is, I’d say its because it allows the connection of two host systems (e.g. 2 personal computers), with no protocol to decide the role either system has to play. Additionally the input of power into a host system via it’s USB ports may cause damage (e.g. to it’s USB controller) because it may lack short circuit or input protection.
The Repair
Now that we have a basic understanding of the structure of the Micro USB plug and where the damage typically is. We can proceed to repair one.
Recommended tooling:
soldering iron
hot air station / heat-gun / lighter
hot-glue gun
precision knife
third hand clamps (handy grips, etc.)
testing adapters
female USB type-A socket breakout board
female micro USB type-B socket breakout board
multimeter
pliers
Consumables:
hot-glue
heat-shrink
Micro USB male plug kit
(lead-free or leaded) solder
rosin flux
electrical tape
P.P.E.:
safety glasses
light heat resistant gloves
The list above is just as a guide the the types of tools and consumables that you may need. Most of them are optional and are subject to personal preferences and circumstance.
Methods of repairing items
Most real world cable repairs I think broadly fall into one of the three categories or ‘methods’ I outline below. They all have advantages and disadvantages. Some allow for saving more time than money and other’s vice versa. Which ones are most appropriate to use will predominantly be based on the repair technician’s personal preference, available materials, and circumstances.
For example one could if one had two good candidate cables, splice them together into a working unit (i.e. method #1) using minimal tooling: just a knife to strip the wires, several unsoldered pig tail splices for the connections, and some electrical tape to isolate the USB wires from each other. And it would work fine. How long for? Who knows – but it will work for the moment and that may actually be enough. I give the example just to illustrate that things can be repaired a number of ways depending on either the person’s (in this case low) resources, and preferences; which can the run the gambit from the “just get it working for now” repair (shown above), to the perfectionist who wants a permanent repair that will outlast the product.
Method #1: splice two cables together
Probably the quickest method of repair involves simply splicing together two cables. This involves cutting the damaged parts off, then joining and soldering the four pairs of wires together according to their colouring. Red and red, green and green, white and white, black and black; and even sometimes the foil metal shielding if present. Simple. However, be mindful to first electrically isolate each of the four individual pairs, then cover over with a larger gauge heat shrink (for neatness) or electrical tape (for cheapness) to group everything together. I recommend a soldered Western Union splice as a method of joining the wires in the pairings. This is due to it’s relatively low profile and due to the mechanical strength of the resulting connection. Which means that in the case of any future tension on the cable such a sudden hard snag; chances are good that the new connection will not break. Nothing hurts my pride quite like having to repair one of my prior repairs. Consequently, I tend to do it properly the first time round.
Now, there are obvious limitations to this method. The most pressing is that cables tend to get damaged in the same spot as each other. Especially when used in the same environment (or by the same people!), and in the same applications. So this method is not applicable in these cases. However in cases where it is applicable it is the shortest and easiest route to creating a reliable and viable cable. Primarily because it effectively bypasses the often finicky business of repairing the actual Micro USB plug.
Method #2: mend and make do (with salvaged spares)
So, like I mentioned above: most of these cables break at the same point. Namely, the male Micro USB plug. So unless you want to end up with a bunch of double ended (full size) male USB type-A cables. Splicing together the good ends of your broken cables isn’t going to do you much good.
So what now? Well first things first. We need to understand the extent of the damage itself. When you examine a broken Micro USB plug. If the metal outer shielding of the plug is present, then chances are that the metal plug itself is bent out of alignment by a fair few degrees across it’s broader sides. In this configuration, the state of the plug’s internal pins is unknown; or more to the point: it is unknown as to whether there is continuity across the pins (i.e. are they snapped or broken). By using a pair of pliers you can carefully correct the angle of the plug. I recommend doing this slowly before trying any other fixes. It needs to be slow, in order to give the delicate internal pins time to bend back into alignment. If the cable works after this, then that means that the internal pins were merely bent and not broken; and it also means that the repair is effectively done.
Alternatively, if after angle correction there is no continuity across the cable. Either by buzzing it out using various adapters and a multimeter — or just by plugging it into (hopefully inexpensive) devices and seeing if the devices recognise each other. Then it is time for a more invasive solution. I stipulate ‘inexpensive’ because many devices with USB ports don’t have adequate protection in cases of hard shorts to ground. It’d be pretty disheartening if a person, for example killed that USB 3.0 port on a their wiz bang gaming rig, because the wires were accidentally soldered incorrectly or shorted on that cheap shit cable they were trying to mend. I doubt that would actually happen, but better safe than sorry.
With a sharp knife, slice into the rubber or plastic sides of the plug. Create a broad slice from where the metal Micro USB plug’s base is (or was), all the way across the plug housing and up close to the strain relief. Peel back the rubber or carefully pry open the plastic to reveal the base of the Micro USB plug. Here you should be able to see where the four wires (for a data cable) or two wires (for a power cable) connect to the Micro USB plug’s base internal section.
This area of the cable: where cable meets Micro USB plug; tends to be either injection moulded with plastic or rubber, or filled with a type of hot glue. It is very easy to do more damage to the plug trying to get to it, then the damage that caused the cable to become inoperable in the first place. So if you intend to repair the Micro USB plug (rather than replace it), I advise proceeding with caution here.
Once you have made it to the base of the Micro USB plug. You many notice that the metal outer shield of the Micro USB is sometimes removable. If yours is, then it should be held in by a clip of some sort. Unclip it. Continue carefully dissembling the plug until you find the fault. In my case the internal pins broke as the plug was bent. I could try to re-solder them together or I could replace the Micro USB base with one from either another plug or a spares kit. Since this is the ‘mend and make do’ method, let’s say I went through the tedium of realigning the tiny pins and soldering them – and without melting their plastic housing or shorting them together no less … What I actually did was just replace the plug base with a known good one, for time and reliability.
Reassemble the plug. Then fill in any cavities you may have carved out on your way in, with hot glue. Close the cable head up, then wrap it in electrical tape. Done.
The strength of this method is that you can repair the cable without necessarily having to purchase additional parts. However the disadvantages are that it is very time consuming and finicky work. Work that could ultimately leave you with a plug that is structurally even weaker than the one you started with. So it may soon break again if not handled with care going forwards.
Make sure to do a through continuity test before pressing this cable back into service. Especially when it comes to testing for shorts across the pins. This includes pin 4, which depending on the testing adapter socket you are using, might be inaccessible. In this case I used to use crocodile-clip leads and needles as probes to test the pins on the exposed male plug without a female adapter. Although, I actually recommend just purchasing (or creating) a female Micro USB socket breakout board. It makes life so much easier than faffing about with a bunch of random low quality adapters or needles … which is what I used to do, and don’t really recommend. But sometimes you have to just use the tools in front of you.
Method #3: use a spares kit
This is probably the simplest actual repair after splicing two appropriate cables together. This method involves using a kit to replace the entire Micro USB plug assembly, including the strain relief. After cutting off and discarding the Micro USB head, remove the outer insulation of the cable, strip the the USB wires within and tin them. If the outer insulation is a fabric braid type, then melt the tip of the insulation with heat to stop it from unravelling.
Next up, slide on heat shrink (for cable bend relief), and then the Micro USB plug housing. This stage is probably easiest to forget. I can’t count the number of times, I have made a really nice soldered connection, only to undo it because I didn’t remember to slide on heat shrink beforehand. It’s funny, it only really happens on the more permanent joints, like the Western Union splice. I think its because I tend to be too preoccupied with making a good strong connection, that consequently: these types of things tend to slip my mind at the time. So take your time and do things methodically.
Just as an aside: heat shrink, in my opinion makes a good form of bend relief for a cable because it makes the cable a little stiffer along the length leading into the plug. This gives it resistance to bending to extreme angles, or allowing repetitive bend or flex damage to concentrate on a singular point on the cable. As for strain relief for the solder joints on the plug base: adding heat shrink to the cable does little. Id est it doesn’t prevent tugging force on the cable from exerting strain on the soldered connections between the cable’s wires and the Micro USB base’s pads. I’d carefully tie the cable end into a loose overhand knot (if it is of a thin enough gauge to do this), making sure not to cause any acute stress points in the wires as a result. This knot will act as a stopper against the insides of the Micro USB plug’s plastic housing. I am not sure whether or not this is generally advisable protocol, I am just stating what I tend to do. The loose knot offers some resistance to a tugging force as it tightens against the hole in the plastic housing. This in turn relieves the solder joints of some of the strain. Alternatively, filling the Micro USB plug’s housing with hot glue will also act as a decent form of (tugging) strain relief for the solder joints. These two methods do this by redirecting the pulling force away from the solder joints and into the housing and general superstructure of the plug.
Moving on. Now with everything in place, solder the USB wires to their respective pads on the Micro USB plug base. This includes the cable’s outer conductive shielding if present. In order to know which pads correspond to which pins: refer to any user guides or datasheets that may have been shipped with your spares kit. Alternatively test the continuity of the pads to the pins using a multimeter and a female Micro USB breakout board.
To connect the cable’s shielding: roll the loose strands into a cord. You may need to wrap this cord with another wire to extend it enough to reach the Micro USB plug’s outer metal housing. Which is a little further away than the USB solder pads on the example kit I have. I needed this extension to the shielding cord because when I cut the cable, it made all the internal wires and strands equal in length, so an extension was necessary in my case. After scratching off the finish on the part of the Micro USB plug’s metal housing that you intend to solder onto. Apply a small patch of electrical tape to insulate the USB wires from the shielding connection. Next, solder the shielding cord to the metal housing. You may need to apply solder to the twisted shielding cord to harden it and fuse the extension if necessary.
Now. Isolate the internal USB wires from each other, by injecting hot glue over and between the four wires. I use the electrical tape from before as a backing for this. I chose to have the adhesive side facing the USB wires, because I intended to wrap it around them at this stage. After this, pull the heat shrink into position then apply heat. Pull the plastic housing over the plug base and align the plug so that it is straight. I used the plastic cap to set the plug’s position. Once satisfied with the plug’s position within it’s plastic enclosure; remove the plastic alignment cap again and inject hot glue to fill any cavities between the plug base and the enclosure. Reapply the alignment cap. Then carefully apply some heat to the now closed plastic housing to make the hot glue within the enclosure melt into all the crevices and hold the alignment cap on. Be careful here because using too much heat can easily damage the plastic enclosure and alignment cap. Once that is done you are effectively finished.
Testing Phase
Although I tend to test at each discrete stage of a repair, for things such as bridged connections between pins or for consistent continuity across connections. I also recommend a final testing phase where we test the resistance of each wire using a USB 2.0 type-A female breakout board and a USB Micro type-B breakout board; or whatever the appropriate boards for the cable you are testing are.
The reason why I do this is to make sure that all the lines are of appropriate conductivity. In other words there aren’t any spikes in resistance in any of the lines that may cause problems when in use. This is especially true for data lines, where resistance will damage signal integrity. Although it is also important for power lines in use-cases involving higher current draws (around 2-3 Amps), such as those used in ‘fast chargers’. If there is sufficient resistance on the VBUS here it will retard the device’s ability to draw power across the cable.
Examples of improvised testing adapters
It’s generally good protocol to have a control test for comparison when testing your repaired cable(s). In this case I used a Samsung brand, model: U2 APCBU10BBE data cable that came new with a smart phone purchase. Please note: the control cable used here is not designed for higher current draws, it’s device needed a maximum of around 700mA to 1 amp when charging.
As you can see, they tested close enough that I feel that the cables that we repaired are of an appropriate quality, at least for me to have enough confidence to press them into service. Alternatively instead of using a control test for comparison, if you manage to find a datasheet for a particular cable you wish to replicate. The data from the datasheet can be used as a target instead. I just found it easier to see how my everyday cable fairs, then try to ape it’s stats. Consequently I do not have a concrete idea of what the resistance tolerances and acceptable margins are for these cables to maintain signal integrity while in use. But I am confident from the comparisons with the control cable that we are within them.
However, if say a cable tested (pulling numbers from my … hat) 15 ohms on a data line. I would inspect the repair, if it seems fine: then the problem could be with the cable itself. For example: such as in a wire where many of it’s hidden internal strands have broken due to repeated localised flex damage. So all the current is having to pass through just a few strands at that point, causing an invisible bottleneck. This should have been tested for at the initial stages of a repair when the cable was first cut and the wires exposed. But still, finding this fault at this stage, allows you to make the informed decision on how to go forwards, either demote it to a power only cable (and mark it as such), scrap it for parts, or find and fix the newly discovered fault.
Eventually, once you reach a stage where you are confident in a cable’s performance, the repair is truly complete and it is now ready to use. Done. This time for real. Thank you for reading.
References / Sources / Further Reading:
https://en.wikibooks.org/wiki/Serial_Programming/USB#What_is_USB? https://en.wikipedia.org/wiki/USB https://en.wikipedia.org/wiki/USB_hardware https://en.wikipedia.org/wiki/USB_On-The-Go https://en.wikipedia.org/wiki/USB_(Communications)#Signaling_state https://www.ifixit.com/Guide/Micro-USB+Port+Replacement/73401 https://www.portplugs.com/how-to-repair-a-loose-micro-usb-port/ https://www.youtube.com/watch?v=36CKsP9YQ1E [why does USB keep changing – NostalgiaNerd] https://goughlui.com/2014/10/01/usb-cable-resistance-why-your-phonetablet-might-be-charging-slow/ https://www.mschoeffler.de/2017/10/29/tutorial-how-to-repair-broken-usb-cables-micro-usb-including-data-transfer/ https://www.mouser.com/pdfdocs/HiroseZX62Datasheet24200011.pdf https://www.howtogeek.com/670644/what-is-fast-charging-and-how-does-it-work/
A little while ago I received a bunch of tools for free from a friend, due to them downsizing their home. Unfortunately these tools were stored improperly and suffered weathering damage as a result. They were essentially stored in a puddle, in a bucket, in a leaky shed. Basically leaving everything rusted to one degree or another.
I took the loot home and sorted the good from the bad. And just as I was about to discard the rest; the sheer volume of rusty crap gave me pause. I wondered as to how much of it I could actually save and refurbish to a useable state. However, I should also mention that I was largely unwilling to actually spend any money on this project. I wanted to see what I could do with the tools and resources I have on hand. Consequently I used household sundries like vinegar instead of a rust remover product, and would’ve used some-kind of random household oil (such as cooking oil or bicycle lubricant) instead of WD40 to loosen any seized tools if I didn’t already have it to hand.
example of rust remover product
Okay, let jump in. These are the tools and materials I used:
It’s a nice small list. So there is little in the way of barriers to entry. Meaning that the strength of this method is that it allows people with very limited resources to simply add salvaged tools to their resource pool whenever they find them, and consequently increase their effectiveness.
Basic Method:
I created an acid bath by mixing water and vinegar in a 1:1 ratio into a (barely) large enough container. Added the tools and waited a couple of days (7+) for the acid to fully react with the rust until the solution formed a thick brown foam on it’s surface. Then removed the items from the bath and scrubbed them down with the wire brush until all traces of rust has been removed.
After which, I finished each item off by it wiping dry with a rag. Then wetting it with another rag laced with WD40, and working the solution into the tools’ various crevices to help expunge any traces of moisture and to provide some protection against any further corrosion.
Notable specifics:
Acid Bath:
The reason why I use an acid bath is to react with and consequently remove the the rust. Rust is a form of iron-oxide compound; the acid reacts with the oxygen in the compound and breaks it as a result. Any residual rust left over after the submerging period will in all likelihood be structurally compromised (softened up) and consequently easier to remove manually with a wire brush.
The reason why I use vinegar is because: one; as mentioned above, I didn’t want to spend money and vinegar was a readily available household sundry; and two, vinegar is a very weak (and consequently safe) acid that will return good results if left to work for a long enough time period. I submerged the tools in it for more than a week before I worked on them. Had I used a stronger acid (such as phosphoric acid) or a product (such as evaporust) I would’ve been done within the day and would not in all probability have to work on the tools with a wire brush.
However by successfully using vinegar, it illustrates that it can be done at little cost. Funnily enough it also adheres to that old adage “you can have it done fast and cheaply, but not good; cheap and good, but not fast; or good and fast, but not cheap.” Vinegar would be the second option in that adage.
Additionally, vinegar is such a weak acid that the chances of it damaging the good metal underneath the rust is said to be minimal. Hence less care and attention is needed with it’s application. However having said that, it seems that vinegar does indeed remove material from the tools (as can be seen within the photograph of the partially dipped shears). Whether or not it started to eat away at ‘healthy’ metal or simply removed a thick layer of rust (including the patina) is hard to tell. What I can say definitively is that more material is lost from the tool in the process of using an acid bath over just scrubbing with a wire-brush.
As a final note on this, a good way to immerse items that are perhaps a little too big for the tub you have on hand; is by using rags to wet the areas of tools that are above the waterline. You don’t even have to dip the area below the water level. As long as the rag touches the solution; the capillary effect of the cloth will draw up the liquid towards the areas of the metal that you have wrapped the rag around. Using wet rags is also a good way to avoid a case that requires using voluminous amounts of solution to fill up a big enough container to submerge large or awkwardly shaped items.
example of rags used in an acid bath
screwdriver before and after
comparison between bathed and scrubbed metal and just scrubbed metal
Mini end nippers:
Anything with a seized mechanism such as the pictured mini end-nippers; required WD40 to be applied and allowed to soak into the joints of the mechanism. After allowing it to soak in, I worked the handles again and again until the joints started moving. I continued this until the rust inside the mechanism was macerated by the WD40, and worked out by the repeating opening and closing of the joint.
A hammer might be needed to apply sudden force to either the tool’s (let’s say pliers) jaws, handle, or the joint mechanism itself to loosen it up in the case of a strong seizure. I used a ball point hammer to help localise the hit just to the specific joint without pointlessly impacting the frame of the tool. A hammer punch will also be very effective in directing and localising applied force. Sharpening the nipper’s jaws with a file is also recommended as a final touch.
washed and scrubbed but mechanism still seized
mechanism lubricated and made operable
Drill bits:
With these I found that holding the brush in the left hand and scrubbing with (i.e. in the same direction as) the thread is the best way to get deep into the bits valleys and remove the rust as efficiently as possible. After the bits are cleaned, they also need to be sharpened with either a small file or some kind of specialised bit sharpener.
complete before and after comparison
drill bits after acid bath, before scrubbing and oiling
after scrubbing and oiling
Personal Protective Equipment:
This is something that is often overlooked by people, however I do think that personal safety is something that people should take into account on any and all projects. Well, as long as you don’t go overboard to the point of the sometimes overbearing British “Elf and Safety” silliness. I have seen people on job-sites with overbearing rules go the complete opposite direction as a form of rebellion as soon as the manager is out of sight. Discarding basic things like gloves and eyewear in the process. Its sad honestly.
I am getting off topic. In this case, the apron keeps the rust vinegar mix off of your clothes as you brush down the items (if you care); and more importantly the safety glasses keep that stuff from flicking into you eyes in a moment of inattention. That’s probably the main reason why I wear these things for everything from soldering to this. Its because I am aware that my attention ebbs and flows as I perform tasks, I am not always in the moment 100% and that’s when accidents happen.
So for me at least. Safety glasses are a must, I don’t want to take any chances with my sight. However everything else is largely optional. I also added gloves to protect the hand that is holding down the workpiece from the wire brush. I put these on to allow me to work quickly and effectively.
The point is, there needs to be a mindful reason as to why and when (and when not) to use PPE in projects, even mundane ones such as this.
References, Sources, Further reading:
https://en.wikipedia.org/wiki/Iron_oxide https://en.wikipedia.org/wiki/Rust https://en.wikipedia.org/wiki/Patina Geoffrey Croker – Rust Removal Methods Explained [https://www.youtube.com/watch?v=Qi-tK1jwO-k] Slavscribe – How to remove rust? Acid vs. Bolt | AcidTube-Chemical reactions [https://www.youtube.com/watch?v=k9OYNPCnLNs]
Now, I am no electrician. However I’d like to think that I know enough to spot when a consumer device isn’t fit for purpose. In this case its a non-compliant (British Standard) BS1363 plug. Look at the above picture, can you tell which one is potentially dangerous. If you (probably, after looking at the title image) said the one with the shrouded earth terminal, you are correct.
So, what is actually wrong with it?
Well, the earth pin’s base is shrouded; in other words: it is electrically isolated. Why is this a problem? It means that any device that you connect to mains with this cable will not be earthed. Worse yet, an inattentive user (that’s most of us): will very likely think that their device is earthed, and thus conclude that they are safe in the event that the device develops an electrical fault within it. It can’t be serious if it didn’t trip the mains, right?
It is especially nasty in this case, due to the layout of contacts within the female socket for the BS1363 type of plug. You see, unlike the Live and Neutral pins whose female contacts are at the base of the socket; in other words contact and mate with the tips of the plugs pins. The earth pin’s female contact is much closer to the mouth of the socket. Consequently, this means that when the plug is fully inserted, the socket’s contact grips the Earth pin closer to it’s base than it’s tip. Under normal operation, this is to insure that Earth is the first pin to make electrical contact when the plug is inserted, and the last to break electrical contact when the plug is removed from the socket. Its actually really quite a lovely design in my opinion, simple and effective.
Unfortunately, this is exactly what makes this particular plug so egregious. When the plug is fully inserted into the socket, electrical continuity will be broken by the non-compliant plug’s shrouding on the base of it’s Earth pin. But the basic user would think that their device is earthed because the tip of the earth pin is exposed in the same way as the Live and Neutral pins. Its the dangerous subversion of expectations that makes this thing so offensive.
image taken from homedepot.com
Why is earthing devices important?
I’ll answer this with a real world example. Imagine a device, something that demands a lot of current. A high amperage device like a portable room heater with a metal chassis. What if it had been either modified or manufactured to use smaller gauge or lower quality wire (e.g. using aluminium instead of copper), or they skipped adding heat-shield braiding to protect the internal wires from the device’s high residual temperatures. Whatever the case may be.
And due to a combination of carrying a strong current and/or the environmental heat, a wire carrying 250 volts mains melts its plastic sleeving and just touches the metal chassis from the inside of the device. If the device (and consequently the metal chassis) was earthed, then the 250 volts would immediately run down the earth path back to the local RCD (Residual Current Device) switch and trip it. This is because electricity naturally takes the easiest path (or path of least resistance) to earth.
However in the case where the device isn’t earthed; then what’ll happen is that the metal chassis will now be at mains voltage potential. Essentially Live. And odds are that the device in question could still very well function in this state, like normal; making it even harder to notice the fault. If then an unaware user touches the chassis, and in doing so presents a path to earth (usually through their hands, then body, then feet). Well, the electricity is likely to travel through them towards earth, probably killing them in the process. That’s why earthing devices is so important. It provides a very low impedance path for electricity to get to earth, in the case of a fault like the one mentioned above.
Aren’t there any other safety measures in place?
I should note that BS1363 plugs have another safety feature that might save the day in the above example. Namely the replaceable (Live side) fuse within it. In the case of this BS1363 to C13, “kettle” plug. A C13 plug’s maximum rating is for 10 amperes. Logically then, the BS1362 fuse in the BS1363 plug should also be rated at a maximum of 10 amps. That is unless one would prefer that the plug give out before the fuse does, in the case of a surge current exceeding 10 amps (but not 13 amps which is the next category up in the standardised BS1362 fuse ratings).
Notably, the phrase “its not voltage that kills, its current” comes to mind. Although this is strictly not true due to the nature electricity. A high current, low voltage (e.g. a 5 volt 10 amp power-supply) shock is relatively safe, in the same way a low current, high voltage shock (such as static electricity) is relatively safe as well. You need both to be high in order to kill people. To bring it back to the point, we are dealing with 250 volts at or up to 10 amps before the fuse breaks and cuts the power supply. That’s more than enough to seriously electrocute a person. Assuming that it is in fact a 10 amp fuse in that plug. Whose to say that a fuse that came within a non-compliant plug, is itself compliant.
I don’t really want to put too fine a point on it. The inline fuse is just another line in the defence to stop people from accidentally killing themselves. The buildings RCD switches, the plugs fuse, the products internal fuses, and earthing; are all lines in the defence between the person and the power, that have the cumulative effect of making them safe.
Just as a fun thought experiment, imagine if all of these safety features where not present, and you gripped the live chassis, well then in that case: you’d probably be cooking until the power cuts off due to lack of payment of bills. Or rather surge protection outside of the property kicks in, but that’s less fun, and in all likelihood McGrippy would be long dead by then anyway.
Where did you even get this thing?
Some background. If I remember correctly, I got the plug along with an unbranded Chinese power-supply from Ebay (or was it Amazon?) a couple of years ago. I took some pictures of it with my dumb-phone (hence the quality images, you’re welcome) due to it’s novelty, but otherwise thought nothing of it. Luckily for one reason or another, I didn’t press it into service.
It was only much later as I progressed in this hobby, did I realise how dangerous it actually was. And after doing some research: I came to the conclusion that one is most most likely to come across these types of sub par electronic equipment from websites like: Amazon, Ebay, Alibaba, Aliexpress, and Banggood. I’m not pointing those particular websites out for any reason, other than their relative dominance of the online market place for consumer grade electronic goods. All ship internationally, and all act more as online market place themselves, then they do actual product vendors. In other words, they aren’t a seller themselves (although some do this too), but have independent sellers operating through their marketplace. Many of these are either drop-ship sellers and straight from factory sellers. Which can sell unbranded and non quality assured dreck; just like this plug.
original images taken from wikipedia.org
What should I do if I have one of these plugs?
It largely depends on you, your use-case, the people around you, and your environment. The puritan in me will say cut it and chuck it. It’s not worth the risk of forgetting and accidentally putting it into service in the future. Especially if you store all your extra cables together as I do.
However to avoid turning it into e-waste, you could just chop it up and use it as spares for repairs or projects. Another thing to consider is: if you are hard up for plugs, you could even scrape the shrouding off of the Earth terminal and use it as a normal C14 plug (after testing it of course, I think the earth pin might be too thin to function effectively/reliably/safely after this). Alternatively just use it as a C17 plug, which doesn’t have an earth terminal so the shrouded earth will not matter in the slightest.
One recommendation I would make regardless, it that you clearly mark and label this cable to differentiate it from the others.
Oh, while I am talking about dangerous non-compliant plugs, look at this thing. Shrouded earth, and not even a fuse. Any device that comes with this plug, just has to be hot garbage… and I sincerely hope you aren’t trusting your household’s safety to it.
References / Sources / Further Reading:
https://www.hse.gov.uk/electricity/standards.htm#appliance https://en.wikipedia.org/wiki/List_of_International_Electrotechnical_Commission_standards https://en.wikipedia.org/wiki/AC_power_plugs_and_sockets:British_and_related_types#BS_1363_three-pin(rectangular)_plugs_and_sockets https://en.wikipedia.org/wiki/IEC_60320#C19 https://images.homedepot-static.com/catalog/productImages/1000/5a/5ab2c7d6-d116-4e66-b78e-a38049a7771c_1000.jpg https://en.wikipedia.org/wiki/Residual-current_device ElectroBOOM – Which is the Killer, Current or Voltage?[https://www.youtube.com/watch?v=XDf2nhfxVzg] John Ward – Dangerous Multiway Extension Lead ASTRA BT311 (Part 2) [https://www.youtube.com/watch?v=C1h9LLJJvk0] John Ward – MK Socket Outlet BS1363 Dismantled & Examined [https://www.youtube.com/watch?v=H1gMYu5VHus] ElectroBOOM – The Outlet that Saves Lives [https://www.youtube.com/watch?v=GlM6PE2kKVY] ElectroBOOM – 7 MILLION VOLT TASER (stun… thingy)!!! [https://www.youtube.com/watch?v=DOMs7mYm_zs] https://hackaday.com/2016/05/19/hackadays-fun-with-international-mains-plugs-and-sockets/ https://hackaday.com/2016/05/11/looking-mains-voltage-in-the-eye-and-surviving-part-1/
The straight solder connection is made by aligning two opposite facing wires in adjacent-parallel, tinning them individually, then soldering them together. This joint is most suited for smaller gauge wires. Especially in low-voltage or low-current applications.
I find I use this joint frequently when prototyping and stringing various PCB modules together, such as power-supplies and buck-boost converters. This is because it allows me to make a more than strong enough bond very quickly; and without damaging the wires, by avoiding subjecting them to repeated mechanical strain. For example: by twisting them together and soldering, then de-soldering and unravelling them whenever I want to disconnect a module; as is the case with the other types of joints. With this connection however, it is simple: align and solder to connect; then apply flux, heat, and pull apart to disconnect.
The straight solder connection is actually rather strong in my opinion. When applied properly, it creates a bond that can not be pulled apart easily. I tested this joint by wrapping the wires around my hands then trying to pull the joint apart. It might eventually give, but only after considerable force is applied.
Despite it’s initial success with my basic stress test; I still wouldn’t recommend using this type of joint for any permanent applications. This is because, in my opinion, I don’t believe that it will stand up well in most real-world settings. Settings that involve: temperature swings, vibration, or constant stress on the wire and joint. These things can exacerbate any small imperfections in the weld to the point that they can create fissures that can either cause problems like intermittent connections or outright brake the bond. Since the solder is the only thing keeping the connection, any stress applied to it isn’t mitigated by anything. This strain coupled with environmental heat would make this type of connection unreliable in the field. An example of this would be wiring around an engine.
Still though, as long as the wire is not subjected to any real or ongoing strain in its application, it is not a bad option to utilise this type of connection. Especially for temporary or semi-permanent add-ons to an already established system. For example adding a voltmeter module to an electric bicycle to keep track of the battery levels. That way the module can quickly be de-soldered off or be further modded later with a switch as an example. This type of bond also has the smallest footprint. Allowing smaller sized heat-shrink to be easily applied as insulation.
PIG-TAIL SPLICE
The pig-tail or rat-tail splice is probably the most common type of connection that I have encountered in the wild. It is made by holding two wires in adjacent-parallel (facing the same direction), then twisting the exposed ends together. Its a quick and dirty solution to make a good mechanical connection. Usually this type of connection is insulated with either sticky tape or even heat-shrink for a semi-permanent solution. It is not soldered in many cases, as the twists and tape tend to make a ‘good enough’ connection for the use-case.
The alignment of the connecting wires is something to take into consideration when deciding whether or not to use this splice. In cases where the wires are to remain adjacent-parallel and facing the same direction; the pig-tail splice is a good candidate. It will allow the user to join two wires next to each other, whilst minimising any change of location, necessary in order for the wires to accommodate the new connection. Example use-case: connecting 2 or more adjacent wires within a ribbon cable. Additionally, with this setup: the connection can be easily soldered and insulated with heat-shrink by sliding it over the open end.
However in cases where the user is joining two opposite facing wires, they are usually left with a connection made up of a twisted pair that veers off at a right angle. This is then folded onto one of the wires in order to apply insulation. This is mechanically weak, as it concentrates any stress on the wire/connection or more accurately “pulling force”; at the bend. The first twist where the two wires meet.
This configuration of the pig-tail splice rarely takes solder well without ending up with an overly large footprint or bulge that the user has to then slide heat-shrink over. It is also too easy to melt the wires whilst soldering because of how close the insulation on the wires are to each other.
To conclude, this connection is good in solder-less temporary or semi-permanent applications. But if you want a more permanent bond (especially for opposite facing wires), the western union splice is a far better solution.
WESTERN UNION SPLICE
The western union splice is named after the Western Union Telegraph Company. This connection involves crossing the exposed ends of two opposite facing wires together, at a mid-point between the wire’s exposed tip and the start of it’s insulation: in an “X” shape. Then twisting them around each other’s exposed base sections. Continue twisting until the insulation of the opposite wire is reached. Then trim off any excess exposed wire tips. This makes a linear and very strong mechanical connection between the two wires; by maximising the contact area the wires have with each other within the connection. It also functions as a knot of sorts, and once properly soldered, it becomes essentially stronger than either wire itself. In addition it has a relatively small footprint and consequently takes to sliding heat-shrink over it rather well.
This is probably my most favoured splice for permanent connections. However for those same reasons, it is also largely inappropriate for temporary applications. This is because it becomes a hassle to de-solder and untangle the wires. This process will also almost definitely damage the wires involved; by fraying and breaking some copper strands from the stress of unravelling.
THE T-JUNCTION SPLICE
The “T” junction splice is any connection where you add a third wire to an existing connection. The most basic version involves removing the insulation from the mid section of a wire; then wrapping another wire around the exposed section before soldering it in place. Then insulating it. This method can also apply to any of the above connections – and the strength of the additional connection usually depends on the strength of the underlying connection.
You could opt to pig-tail together three wires into a T-junction (or four into an “X”, etc…), or straight solder three wires, or even create a western union splice, then tightly hitch the third wire over that connection for maximum strength.
At its most basic a ‘T’ junction splice is exactly that. Three wires connected together in a rough ‘T’ shape. Everything else is up to the user, and largely depends on the use-case and it’s needs.
This will be a rather basic guide on how to clean out a device after an alkaline battery leak.
Whenever I come across an old device, that for some initially unknown reason refuses to power on. Chances are, that someone left disposable alkaline batteries inside it, and that they have leaked. There are a number of reasons as to why people leave batteries inside devices. Predominantly: laziness, ignorance, or forgetfulness. There are also a number of reasons as to why these same forgotten batteries leak. Batteries with mixed charges, reverse charging each other, or a constant low current draw causing leaking; are but two examples.
Unfortunately, a more in depth look into what causes disposable batteries to leak is outside of the scope of this article. However it is something that I am interested in exploring at a later date. Check the further reading section of this article for the hotlink to that, when I eventually get round to penning it.
I cannot count the number of times I have opened the battery compartment of a device, that has been left in storage for a while; only to be greeted with a vented battery, rust, and the the blue-white fuzzy carpet of alkaline crystals growing out of it. Meshing into, fusing with, and corroding the negative terminal’s spring contacts. This infection then proceeded down the circuit and further into the device and onto more complicated/valuable components. In this regard, an unstemmed battery leak has the potential to brick a device.
So, how do you deal with it? Well, if caught early and the leak hasn’t progressed far beyond the battery itself, and a bit of surface level corrosion on the spring contacts; then it is really not much of an issue. A quick wipe down with a damp cloth after disposing of the batteries, should suffice. I recommend using isopropyl alcohol to dampen the cleaning cloth, mainly because it becomes non-conductive very quickly by evaporating readily. It also doesn’t leave any contaminants like water might. However water is fine to use in a pinch; just make sure it is fully evaporated and that there is no substance residue left after cleaning; before you power up the device.
If the leak has had the time necessary to progress further into the circuit and deeper into the metals. That’s when you have to take more invasive steps in order to remove it. There are two main ways to deal with an advanced battery leak. Which one to use, largely depends on circumstance. The most important factor being whether or not the affect parts can be removed from the device.
Method #1: Acid Bath
The first method of remedy, requires the removal of the affected parts and the use of an acid bath. Removing the affected parts, will likely require de-soldering. Next, create a bath, of vinegar and water at a ratio of approximately 1:3. So 25% vinegar and 75% water, or thereabouts. This leaves you with a mildly acidic solution for you to submerge any affected parts within. Mix the solution well, then drop the parts in. Leave it for some time. How long for based on your own judgment. I recommend 30 minutes to a couple of hours depending on the invasiveness of the alkaline crystals into the metals.
Remove the parts from the solution when you think that they have been in there long enough. At this point, they will require brushing down, to remove any stuck on materials. Use a strong bristly brush for this, something like a firm toothbrush will do. For those wondering, a wire brush would probably be overkill for this application, especially since the subjected parts would likely be rather small, and wire brushes are traditionally made for uses with larger items. Wire brushes will also likely remove the finish on the metal parts, that is if the acid bath hasn’t done so already.
The main reasons why I recommend using a mildly acidic solution to counteract the alkaline crystals is: one, in order to minimise the severity of the reaction between acid and alkaline; and thus minimise the chances of additional corrosion or damage done to the metals in the process; and two, to minimise the chances of the acid removing or damaging the metal’s finish by reacting with it. It should be noted that plenty of parts in modern mass produced devices are made up of mixed metals, then given a chrome finish for uniformity.
I should note that when I say ‘part’, I am referring to simple primarily metal constructs within devices; such as spring terminals or basic switches. I am not referring to more complicated components such as resistors, capacitors, transistors, or anything more sophisticated than those examples. This is because the acidic solution is very likely to compromise the internal structure or chemistry of any components submerged within it, if the leak’s corrosion hasn’t done so already. Bricking the component in the process. More on what to do with leak affected components mentioned later.
After brushing all foreign materials off of the parts, dry them off, then wipe them down with a cloth laced with isopropyl alcohol. Continue until you are confident that you have removed all contaminants including traces of alkaline crystals and the acidic solution. Once this is done leave the parts to dry fully, before then placing them back into the device and likely soldering them back into the circuit they come from. That’s it, done.
Method #2: Acid Wrap
The second method of removing alkaline crystals is used when the affected part cannot be removed either from the device or it’s circuit for whatever reason. A good example of this is when a part is either welded, crimped, or glued into place; making it’s removal potentially too destructive to consider lightly.
This method requires either tissue paper or cloth. Id est, something that can soak up liquid and cling to a particular structure without external pressure/force. I use tissue paper for this example. Soak the tissue paper in a diluted acidic solution; enough so that it has plenty of solution available but not enough that it drips excess. Then wrap it around the affected parts and wait for time, before removing it and brushing off any loose materials. Rinse and repeat until it looks done. Then clean and wipe down the part with an isopropyl laced cloth. Done.
You can adjust the ratio of vinegar to water to your liking. I still recommend a mildly acidic solution to minimise the severity of the reaction (and any damage caused from it), but the more acidic the solution is, the quicker it’ll dissolve the alkaline crystals off of the affected parts. From my experience a ratio of 1:1 seems to work out well.
Another tip for this method is to properly isolate the rest of the device from the part you are currently working on. This is done to avoid any accidental drips from the tissue paper or off-spray caused by brushing. Vinegar-water and electronic components are best left separated. With that in mind, I recommend using a plastic bag and tape. The plastic bag functions as a waterproof membrane and the tape holds it in place. Simple.
Dealing with components
Now that the basic method of cleaning metal parts has been explored, you may be wondering as what to do when the leak has reached more complex components. Well, the answer is simple. Try to remove whatever battery residue you can mechanically; i.e. just using a brush or a small chisel of some sort. Then de-solder/remove the component from the circuit. Test it appropriately. I recommend having both a multimeter as well as a multi-function tester on hand for this. If it is still within specification, solder it back into circuit; if not, replace it. There is not much one can do for any affected components beyond this. Once a capacitor or resistor is broken, it needs to be replaced.
Conclusion
As a final note, I should also mention that in a lot of situations: replacement of the affected metal parts is probably the more appropriate recourse to severe leak damage then repair might be. This means replacing spring terminals, and creating jumper wires as replacements for corroded PCB traces. This is because the repair can weaken the metal, leaving one with brittle spring terminals or a trace with more resistance in it than initially intentioned. However having said that, if you either can not remove the part, or don’t have the prerequisite replacements: then an ugly repair is better than no repair at all.
