# Corsair Strafe Keyboard has certain keys not working after small water spillage



## tech_no (Jun 12, 2007)

Spilled a small amount of water over the bottom right corner of my Corsair Strafe keyboard. Switched it off and turned it on its end and a little water drained out of it. Let it dry for 3 days but once switched on certain keys failed to operate, namely both zero's, full-stop, return and the P key. All others working ok. Stripped the keyboard down and it was completely dry inside and no water marks or visible damage. Cleaned the back of the PCB with Isopropyl Alcohol only where it looked a little dirty.
Tested all mechanical switches for continuity with a multi-meter. All working. Next with a wire I tried powering those keys that weren't working by joining the wire from the positive of the key next to it. This makes the key work again but it takes on the letter of the key that is powering it somehow? This happens with all of the keys that were not working, so if I take the power from the hash key to power the return key that key now also becomes the hash key.
I know nothing of how a keyboard assigns each key but I am guessing it has an onboard processor?
I am guessing my keyboard is past repair? Has anyone any other solutions or does anyone know why the wrong letter is being assigned to each key that isn't working?
Any help appreciated. I'm just exhausting all possibilities before buying a new keyboard.


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## Corday (Mar 3, 2010)

Not for gaming, but for older computers, Ive bought recommended and used a $10.00 keyboard from Big Lots with no problems ∴ I never thought about what makes the keyboard work.


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## SpywareDr (Jun 15, 2013)

The main problem with spilling electrically conductive liquids inside of electronic equipment is they allow electrical currents to travel across unintended paths. This can *immediately* cause damage to the electronic components that those improper currents traveled through. In order to find out exactly what was damaged and where would require proper testing equipment, as well as the knowledge required to use the equipment and perform the tests . . . the cost of which could far and away exceed the cost of pallet loads of replacement keyboards.


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## bassfisher6522 (Jul 22, 2012)

You might want to chalk that up to the "life of hard knocks" and bite the bullet and buy another keyboard.


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## tristar (Aug 12, 2008)

The challenge with water damage of electronic components, you never know where the water crept in unless it takes a few days and oxidation kicks in, you'd see some white/bluish coating which you might have to clean, run a hair dryer to remove any trace water/moisture.. Chances are the pads/dots/holes which act like connectors may have lost connection, so the hole/pad runs through the board, i'd typically test this connectivity using a multi meter, if that does not have a connection, I'd strip the winding wire from an old motor, remove the sleeve, run it through that hole and solder both ends..

The keys connections are like a grid/matrix (from my experience with servicing cell phones) so A1 A2 A3 etc... followed by B1 B2 B3.. and so on... The usual way of connecting the grid, all As Bs 1s 2s 3s etc are connected with a single connector/pcb line/trace whatever you want to call it..

So if you need to fix key B2, you need to connect one part to the main trace on Bs (which are connected) and the other part to the 2s(which are connected) this will help complete the grid of the key...Usually the keypad outer rings are connected with a single line and the inner dots to their own line.. So test the connectivity of a single Row/column and you should be able to figure out which one goes where.. Hope this made sense to you.. once you figure out the matrix you can fix most keypads, my best guess is that the Keyboard works in the same fashion as well, so as long as you figure out the matrix, you can fix the keys...


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## tech_no (Jun 12, 2007)

Thank you all for your answers. I think the keyboard is past repair but you have given me a glimmer of hope tristar by describing how you expect the keyboard is wired up on the PCB through its traces. I will have a last ditch attempt at connecting the positive terminal of different keys, to different parts of the keyboard in the hope that somewhere I will be on the right part of the circuit so that when the key (one that wasn't working) is depressed it will type the right key.

You've all made good points about how water ruins the PCB; there is only a small gap between the PCB and the case bottom. Although I have cleaned the face of the PCB and have found no discoloration or water marks on it, it isn't possible to see or clean between the back of the PCB and the metal chassis. The only way to view that side would be to de-solder every key and then un-slot the PCB & metal chassis from each other.


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## tech_no (Jun 12, 2007)

The keyboard is fixable. You were right tristar. I carried on testing with my wire held on the positive post of a key not working and went through holding the other end of the wire on each key on the keyboard. 99% of the time I still got the effect of the key powering on but it then taking on the key the wire was being held onto. However I came to the Plus Key above the bottom right Enter and the first key that was not working suddenly became what it was meant to be. Strangely enough this Plus Key became the only one that makes every key that isn't working into its rightful key. How I don't know?
My next step is to solder a joining wire from the Plus Key to all of the keys not working. I haven't soldered into a PCB before but I have been watching instructional videos on it.
I think the best way is for one wire to be soldered into the positive of the Plus Key and then to join all of the connections from each wire from each key that didn't work before. I expect they have to have to have shrink wrap around them where the join is.
I was ready to scrap this keyboard and I expect most people would. Thank you very much tristar for your help. It was well worth posting on this forum, as I have found many time in the past.
Would you like to leave this post open until I solder the wires in? I have to order materials online first.


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## SpywareDr (Jun 15, 2013)

Cool. :thumb: 

And yes, post a picture or two when done?


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## Rich-M (May 2, 2007)

I think you are on your way but a few of you sort of missed the point and "tech no" was nice enough not to say it, but this is a $100 keyboard, not a $10 keyboard and well worth the effort to try to fix it!
https://www.amazon.com/CORSAIR-STRAFE-Mechanical-Gaming-Keyboard/dp/B00ZUPOMDQ


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## tristar (Aug 12, 2008)

Good to see I instilled some hope.... Like Rich says, it's a $100 keyboard, I'd try to squeeze any and every step possible to revive it..This post will be open as long as some activity is there  So do keep us posted with some regular updates.. Digging deeper, here's another analysis...

The Matrix could be connected in series, A1--A2--A3 and such, for the sake of argument, if A1 is the '+' key chances are other keys sequential in this series will not work if there is a break in trace between A1-A2 thereby rendering A3/A4 unusable..

Instead of pulling a lead from A1 ('+') and running it to each of the other keys, I'd rather figure out if the sequence A2--A3--A4 are still having a connection and just solder one lead connecting the A1('+') to the existing A2--A3--A4... Connection and you should be good to go... The challenge is figuring out the matrix..instead of soldering on the gold contact use the small pad/dot/hole to perform your soldering, my guess is, one of those holes has lost contact... figure that out, use a very thin stripped copper lead, pass it through, scrape the ends of the pad/dot/hole(s) and solder them both ends, you should have a working keyboard and we'll get beers from you


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## tech_no (Jun 12, 2007)

Sorry I haven't been in touch recently. I have been trying to order the right soldering gear, not having a clue myself, so I have been getting advice from online electronic companies. I have ordered a Hakko FX888D soldering station and a D16 Tip, Rosin Flux Solder, De-solder Braid etc. The hard bit for me is doing the job but you have to start somewhere.  Hopefully this will lead to other repairs of this kind.

Thank you Rich-M for pointing out that it is an expensive keyboard and well worth saving.

tristar, if the keyboard has some kind of matrix system the keys that are not working are not connected to any matrix now. You have guessed that the water has damaged the traces on the PCB and I am sure you are right. However, visually even with a magnifying glass the PCB looks perfect. I have scrubbed the surface of the PCB, with a soft nylon brush, with Iso-Propyl Alcohol but it has made no difference.

My plan is to de-solder each positive post on each key that isn't working using a solder sucker and then de-solder braid. I was going to use either alarm cable (a single insulated wire) or telephone landline cable (a single insulated wire). I was then going to re-solder the positive terminals of the keys not working with the small wire attached to each, other end of each wire left free for now. Lastly re-solder the Big Positive Key (above Enter). I was then going to join all of the free ends together and solder them together with lastly heat shrink around them. These soldered ends would stick up into a free space above the PCB and under the top plastic casing. 

Please let me know if this is an OK way to solder the wires. I have attached 2 photos to show you what the PCB is like before soldering and how the red, metal chassis is attached. All of the keys fit through the chassis before being soldered to the PCB when the keyboard was made. 

I cannot find any matrix. I used a fine test wire that was held on one key that wasn't working at a time and went through every key on the keyboard. This was repeated for every key not working. There is only one key that makes the key not working its letter or number that it is meant to be and that is the big + symbol, above Enter. Every other key makes the key that isn't working the same key that the test wire is held on. I hope this makes sense.

There are no holes on the PCB to pass the wire through tristar unless I de-solder first. I have provided the photo of the PCB in case you can see something I have missed. You cannot pass the wires over the red chassis as it would show with the illuminated keyboard.

Any advice will be welcomed. Thank you.


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## bassfisher6522 (Jul 22, 2012)

My keyboard at the time of purchase was $179....it's not about price, it's about water/liquid damage and the severity of it.

Obviously by teh no last post there's some significant water damage. What seems to be the only way to fix it is to jerry rig it as he is doing. If he gets it to work...well then great. If not he has the satisfaction of trying. 

That said there's 2 options that I see he can take if the jerry rigging doesn't work, 1 is to replace the PCB if it can be replaced or 2 buy a new keyboard.


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## tristar (Aug 12, 2008)

I think at this point, you might need to remove the board from the below unit, this will help you identify if there is any oxidation on the rear of the board. I'm unable to locate the + key, any chance you can provide a blown up picture of the area around the + key with the key centered (or a red arrow or circle or something as a highlight) ?

Also, can you post a blown up picture of the rear side of the board with the contacts of the + key centered ?


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## SpywareDr (Jun 15, 2013)

I believe these (yellow circles) would be the *+* key locations:


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## kendallt (Feb 21, 2007)

I've used pencil erasers to get rid of oxidation on contacts a few times. 
In many cases the problem isn't with the contacts on the board, but on the moving part, underside of key or the membrane. 
If the liquid was sweetened, it will often form an insulating 'skin' on the contacts.
Don't go nuts on the erasing, especially if the contacts are the black carbon-ink types. 
Mechanical pencils with the small diameter erasers work well for close quarters. 

I'm the type that fixes stuff all the time, not so much to save money, but simply for the enjoyment or the challenge of doing it.


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## tech_no (Jun 12, 2007)

tristar, the PCB is completely removed from its casing, it was just resting on the lower casing. Sorry about the poor quality photos, I have taken a lot more which I will be posting very soon. There was no oxidation, verdigris, staining or marks of any kind on the Soldered side of the PCB. Only thing I could find was a little rust up the other end from the water damage on a steel post that has been soldered on to. Please see photo of this. The red plate, where each Cherry MX switch clips into is made of steel. It is rolled over at every edge so I cannot inspect the other side of the PCB unless everything on the PCB is de-soldered. You will see this in my photos. The red plate slots into the PCB sideways before its soldered during manufacture. You will see the red steel lugs that poke through the PCB and slot into it. I have provided photos of the big + key (above Enter, bottom right hand side), that makes all of the keys work, ringed around in red and a photo of all of the keys that have stopped working, again ringed around in red.

SpywareDr. you are spot on with your green circles. It's only the bigger + key over the Enter that makes the keys work though.

Thank you for the information kendalt, that is very interesting about your methods of removing oxidation. I did clean the whole PCB with Iso-Propyl Alcohol but it looks exactly the same as it did when it was first stripped.

I have always been very keen to fix anything that is broken and have a passion for it. It's why I became a mechanical engineer. It's like kendalt says, it's for the enjoyment and challenge too. 

Thank you for your input too bassfisher6522.

Please let me know, any of you electronic engineers, if my idea for fixing the keyboard and my methods for de-soldering the positive posts, on the keys not working, is right. I have my soldering station at the ready. It's just knowing how to use it:smile:


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## tech_no (Jun 12, 2007)

Further photos.


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## tech_no (Jun 12, 2007)

The black plastic flap, top left corner of PCB, covers a micro switch. Does anyone know what the switch triggers? It must trigger when you remove the PCB.

Holding the micro-switch in whilst testing doesn't change anything.

The USB socket still works.


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## tristar (Aug 12, 2008)

So the last pic, which has the red circles are all keys which are not working ?

Sorry, my laptop is limited to a crappy 1366 resolution, so even if I blow up, I have to really strain my eyes to follow the trace.

Let's start with the 4 keys to the right...

Use a multi meter, check the connectivity between each of those switches, check all the left ones first and see if you can find a pattern, do the same for the right side.


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## tech_no (Jun 12, 2007)

Hi tristar

Yes all of the keys with a red ring around them don't work.

I have a multimeter but can you talk me through where to place the probes that you have asked me to test as I am a beginner in electronics.

I think I need to use the continuity test setting between the keys not working. Do I just test positive to positive or positive to negative on the key posts?

Sorry for asking what must seem basic to you and others.


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## tristar (Aug 12, 2008)

No issues, all good.. The more questions you ask, the more it helps other folks who would stumble upon this post.

Yes, you're right, you need to set it to the continuity test, check ++ & --do all permutations among the keys, A1-A2, A2-A3, A1-A3, A2-A4... so on...


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## tech_no (Jun 12, 2007)

tristar, there is a sequence as you say to which keys are joined to others. It's usually the keys around the key that are joined to it or an whole line sometimes on the keyboard joined to a key that is being tested.

None of the keys that are not working work when joined to each other but I suppose that is to be expected. However all of the keys not working become live when joined to certain keys.

I have tested what keys connect to each key not working, one at a time.

The top zero key connects to: dash, 9, 8, 7, 6, 6, 4, 3, 2, 1 and ` key.

The P key connects to: left bracket, O, I, U, Y, T, R, E, W, Q and Tab key.

The ;: key connects to, L, K, J, H, G, F, D, S, A, and Caps Lock

The .> key connects to: ?/, <,, M, N, B, V, C, X, Z, \| and Small Shift key.

The Return Key connects to: ]}, #~, Insert (next to back space), Home and Page Up.

Down Arrow key connects to: Up Arrow, Left Arrow and Right Arrow key.

Number Lock key connects to: / (over numerical keyboard), *, - and Big + key (above Enter key)

Bottom Zero key (on numerical keyboard) connects to: . with Delete key, 3, 2, 1, 6, 5, 4, 9, 8 and 7.

We know now which keys can power individual broken keys. My findings before showed, using the test wire, that anything but the big plus key made each broken key into the key that was powering it. I will try with my test wire again by holding on the positive post of a broken key but this time only using the keys I know that will power that key. 

It's strange that the big plus hasn't shown to power all of the keys in the continuity test although it did using the test wire.

I will post a photo of the keys on my keyboard, as some keyboards differ slightly in their layout, so you can follow easier which keys connect. Sorry the keyboard was dirty when it went wrong.


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## tech_no (Jun 12, 2007)

I have just done the same test as above except this time with the keyboard being USB powered to see if any more keys connect to each key not working. 

I found with most of the keys I got the same amount of keys connecting as before but on others I had more keys connecting.

I used the multimeter with the continuity setting on as before.

These are my results:

Number Lock key: Enter was added to my list above.

Bottom Zero key: No keys added.

Down Arrow key: Delete, End, Page Down, RH Ctrl, and RH Shift key. All added.

Return key: Pause, Scroll, Print Screen and F12. All added.

Top Zero key: No keys added.

P key: No keys added.

;: key: No keys added.

. > key: No keys added.

I then pulled out both USB cables from the keyboard and performed the same test. However, all of the keys that I added to my list with the keyboard USB powered were now all showing up as continuous with the USB dead.

Does anyone know if a keyboard holds its charge after being powered on? 

The only other explanation is that I missed all of the extra keys on my last test.


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## tristar (Aug 12, 2008)

If there is a capacitor in the circuit, it will hold a charge, that is the role of a capacitor in a circuit.

Now, you've done continuity tests, the next big part is to actually look at the traces and follow them as to where they go. Pick a key, follow both the leads, trace the lines and see where they actually go, if there is a pad/dot, the continuity will continue on the opposite side of the board, see if you can build trace lines, don't do any soldering yet..


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## SpywareDr (Jun 15, 2013)

Also, a multimeter usually contains at least one 1.5V DC battery for testing continuity.


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## kendallt (Feb 21, 2007)

You need to find a copy of the keyboard matrix for that, then you can really narrow down the problem. See if the non-working keys are all on the same circuit in the grid or not. If they're on the same leg, then it's something in the circuit itself, if they're not then it would indicate the pots themselves. 

If it's the pots, use a syringe and alcohol or warm water to flush them out, let dry completely and retest. For some reason was thinking membrane type switches in earlier post, not relevant with cherry pots. 

image included for a rough idea of what I mean. 
If the circuit for row one is bad, none of the keys in that row will work 
If column one, the first column won't work. 
would be nice if circuits were as orderly as the schematics...

The location of the circled keys shown seem pretty spread out to be 'connected'.


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## tech_no (Jun 12, 2007)

tristar, I have made a rough sketch of the traces path. I can see now that the ones that suddenly end must be joined to the other side. However, I am not sure of some of the components and what they do to the trace pathway?

In one case a trace passes through a small silver component and I am not sure if that means whether it carries on to the next key or not?

I one case the trace is blocked by a dash of white paint, this must be deliberate.

The dark green shaded areas on the PCB, I think must be insulating between the positive and negative posts of each switch?

Am I right in saying that there are two lines of traces to each positive post of a key?

I can see the very tiny holes in the PCB now that you talked about in one of your earlier posts.

I cannot see a capacitor in the circuit unless it is mini one that I haven't recognized.

SpywareDr my multimeter has a 9V battery in it for continuity testing.

kendalt, do you think there is a copy of the PCB diagram? Wouldn't Corsair hide such things or do you think the PCB makers would have one somewhere? I tested each Cherry MX switch for continuity and they are all working but thinking back the first time I used the keyboard after the water damage the P Key wasn't as springy as it should be but it did come back to normal after awhile. You are right, I now know that the keys not working are not connected on this side of the PCB. Thank you for the diagram. I have found a + and - at the edge of the board. I assume its for testing?

Would it be possible for this to be a Cherry Switch problem even though they all pass continuity? I wouldn't think it possible myself.

I'll post my very rough sketch of the traces.


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## tristar (Aug 12, 2008)

tech_no said:


> tristar, I have made a rough sketch of the traces path. I can see now that the ones that suddenly end must be joined to the other side. However, I am not sure of some of the components and what they do to the trace pathway?
> 
> In one case a trace passes through a small silver component and I am not sure if that means whether it carries on to the next key or not?


I'm guessing you're referring to the small glass like object on the board, if you look at it closely, it will have like a scarlet/red and black terminals encased in a sort of glass, that is a diode, 



> I one case the trace is blocked by a dash of white paint, this must be deliberate.
> 
> The dark green shaded areas on the PCB, I think must be insulating between the positive and negative posts of each switch?


Not necessarily, the paint is mostly used to avoid the underlying copper from getting oxidized.



> Am I right in saying that there are two lines of traces to each positive post of a key?


Not necessarily, there could be 1,2 or more, but that is the key, you might want to look for a connection in the '+' key, that seems to point to the pad/dot which has a lot of traces coming in to it.



> I can see the very tiny holes in the PCB now that you talked about in one of your earlier posts.
> 
> I cannot see a capacitor in the circuit unless it is mini one that I haven't recognized.


They can be very small cuboids, usually brown or gray/black in color with silver solder on either end.

The keyboard could have 'Gates' as well so if you use the 'Shift' Key it's supposed to simulate a different key and so on...

If there is a diode in the circuit, skip it and continue to test the connectivity from the other end of the component. If you encounter a dot, use a small needle press them against the metal of the leads/probes of the multimeter, and *(dont push too hard)* just slightly push it in the dot on either side and you can further test the connectivity.

There are chances that once you test this the oxidation in the dot/pad may clear and establish your connection and some key starts working again, so make notes as and when you test the dots/pads.


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## tech_no (Jun 12, 2007)

Hi tristar,

I have enclosed a photo (photo 2) of what I think are the diodes you refer to. there is a red ring around them. Can you confirm please?

I have enclosed a photo (photo 4) of the dashes of white paint. I see now that it isolates the positive to negative where the light diodes are on each key (red rings around). It seems to be used where there are supports for the bigger keys too.

I have enclosed a photo (photo 1) of what I think are two traces, one going around each side, of positive posts. Red rings around them. Am I on the right track?

I was referring to the small holes on the PCB in my last post. The ones you said I may be able to solder wires into instead of disturbing the key posts.

I can't see a capacitor unless they are the very tiny black cubes. Could you point one out on my PCB please?

What I thought was a silver component in my last post was solder on each close together trace. I have enclosed a photo (photo 5) of this, red ring around. I guess the trace path is not effected by these small lumps of solder?

I have enclosed a photo (photo 3) of testing points on the edge of the PCB. Should these points read continuous with the USB connectors connected or not?

I have done a lot more testing with my multimeter tonight. The rough sketch I posted yesterday is nowhere near complete. The keys I thought went nowhere connect to other keys on the PCB. I have tested for continuity whole lines of keys tonight. Probe on each end and they are all continuous which must show no break in the traces along the tested line. These are lines where there are keys not working too which must suggest it isn't a trace problem.

I was trying tonight to gradually slide my probe along the trace whilst the other probe was on the positive side of a key but this doesn't work does it? Are the traces covered in something, such as varnish? I couldn't get any reading doing this.

I can't understand this part tristar, sorry.

"_If you encounter a dot, use a small needle press them against the metal of the leads/probes of the multimeter, and (dont push too hard) just slightly push it in the dot on either side and you can further test the connectivit If you encounter a dot, use a small needle press them against the metal of the leads/probes of the multimeter, and (dont push too hard) just slightly push it in the dot on either side and you can further test the connectivity.

There are chances that once you test this the oxidation in the dot/pad may clear and establish your connection and some key starts working again, so make notes as and when you test the dots/pads. _


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## tristar (Aug 12, 2008)

tech_no said:


> Hi tristar,
> 
> I have enclosed a photo (photo 2) of what I think are the diodes you refer to. there is a red ring around them. Can you confirm please?


Yes, correct.



> I have enclosed a photo (photo 4) of the dashes of white paint. I see now that it isolates the positive to negative where the light diodes are on each key (red rings around). It seems to be used where there are supports for the bigger keys too.


The white paint is a marker there which indicates it's the +ve terminal of the diode, which is reiterated by the band.



> I have enclosed a photo (photo 1) of what I think are two traces, one going around each side, of positive posts. Red rings around them. Am I on the right track?


No, the complete line, joining those solder points (circled by you) constitute a trace/track... 



> I was referring to the small holes on the PCB in my last post. The ones you said I may be able to solder wires into instead of disturbing the key posts.
> 
> I can't see a capacitor unless they are the very tiny black cubes. Could you point one out on my PCB please?


My screen resolution sucks really bad, I can't seem to get a closeup of the picture, sorry, they're very small, the small black box type of components are probably capacitors or could be resistors, can't seem to see it due to the low resolution 



> What I thought was a silver component in my last post was solder on each close together trace. I have enclosed a photo (photo 5) of this, red ring around. I guess the trace path is not effected by these small lumps of solder?


I can't see that either  very small.



> I have enclosed a photo (photo 3) of testing points on the edge of the PCB. Should these points read continuous with the USB connectors connected or not?


Yes, look closely, you will see a green line connecting them all, which means that is one single trace/track and should show continuity end to end.



> I have done a lot more testing with my multimeter tonight. The rough sketch I posted yesterday is nowhere near complete. The keys I thought went nowhere connect to other keys on the PCB. I have tested for continuity whole lines of keys tonight. Probe on each end and they are all continuous which must show no break in the traces along the tested line. These are lines where there are keys not working too which must suggest it isn't a trace problem.
> 
> I was trying tonight to gradually slide my probe along the trace whilst the other probe was on the positive side of a key but this doesn't work does it? Are the traces covered in something, such as varnish? I couldn't get any reading doing this.


Yes, you need to measure the ends of the track (green line which connects all the points), if there is a component in between test it till one terminal of the component and then start from the other.

I can't understand this part tristar, sorry.



> "_If you encounter a dot, use a small needle press them against the metal of the leads/probes of the multimeter, and (dont push too hard) just slightly push it in the dot on either side and you can further test the connectivit If you encounter a dot, use a small needle press them against the metal of the leads/probes of the multimeter, and (dont push too hard) just slightly push it in the dot on either side and you can further test the connectivity.
> 
> There are chances that once you test this the oxidation in the dot/pad may clear and establish your connection and some key starts working again, so make notes as and when you test the dots/pads. _


Look up white paint on PCB jpg file, look at the lower left Diode *DA5* if you look at the positive terminal, there is a small green line which goes out towards the left and ends at a pad/dot. This is the point I'm referring to, now this point connects to the other side of the motherboard.


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## tech_no (Jun 12, 2007)

Thank you for your answers tristar.

I can understand about the dots that connect to the other side now.

I have tested everything I can with the multimeter, as far as I know, and have made a map of which keys connect to the non working keys.

I have tested along nearly whole rows for continuity (the ones I know connect) and the traces seem continuous. Probe each end of the row.

I have tried connecting non working keys to the keys I know are continuous, with the key being tested, but unfortunately it doesn't get the non working key to work. This is done by holding a thin wire to the positive post of each key. Even connecting between the key not working and the big plus key, above enter, doesn't seem to work in most cases tonight.

The only key I can get working is the downwards arrow key by connecting it to the plus key (which strangely isn't a key that is continuous to it according to the multimeter).

I found the test + and - on the top edge of the PCB is not continuous at those points with the keyboard bus powered or non bus powered.

I tried soaking inside the P key with Iso-Propyl Alcohol this afternoon with no results.

I have not given up if there is anything else to try but I have I think I have exhausted all possibilities.

I read on the reddit website that somebody said his keyboard had cold solder connections. He re-soldered and it worked. What do you think?

Any ideas would be welcomed.


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## tech_no (Jun 12, 2007)

Does anyone know how long it normally takes for a membership query to be answered?

I have written twice since I started this post about not being able to change my system spec.'s or not being able to change my e-mail address. It just reverts to the old one every time I try to change either.

My e-mail address is a very old one and doesn't work any more.

Thank you.


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## Corday (Mar 3, 2010)

When you go into the User CP and make a change, you must also choose "Save Changes".


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## tristar (Aug 12, 2008)

I guess then we still might not have figured out the matrix correctly...

You cannot bypass a Diode if it's *in the path of connectivity*, well you can, but shouldn't... So if the + leads to a diode and then to the other key, then you need to connect it to the lead of the diode which directly connects to the other key, not the failed one..

Also check the diodes as well, connectivity of either end of the diode, they should have 1 way connectivity, if they show a 2 way connectivity, there is a possible short..

Regarding Cold Solder, if you look closely at the leads/Legs of the component soldered on the other side, if you can see a gap or the prong/lead/leg moving, then it could be a cold solder.. These are cases where the prongs/leads/legs do not contact with the connection on the board.. I usually call them dry solder, I'm guessing that's what they call as cold solder..

I couldn't find any schematics for this keyboard  this is a backlit keyboard with how many keys ? I'll try to lookup a similar board..


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## tech_no (Jun 12, 2007)

Hi Corday,

Thank you for your reply. I have tried to save changes every time but once you press save changes it reverts back to what it was before unfortunately. Must have tried about 10 times.

Hi tristar,

It doesn't seem that a diode is any of the pathways but it must be as there is a diode per key. All of the diodes I have tested are dead; no continuity either way. The light diodes (if that is what you call them?) are all continuous. I realized the current can only flow one way through a diode one way and they usually have a + above one end on the PCB.

I will have to tidy my notes and take a photo of the trace mapping I have done.

I don't think I have any dry soldered joints after reading what you say.

Yes it is a back-lit board and each key is illuminated separately. There is a photo I have posted on this page with the full layout of the board with the keys in place. There are 17 keys for the numerical keyboard. 16 keys top row and 88 keys for the rest of keyboard I think.

I will try testing more of the other keys tonight individually, i.e. the keys that are working too.


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## tristar (Aug 12, 2008)

If those are indeed zener diodes, they should show 1 way continuity, but due to my crappy laptop, I'm having low visibility sorry 

Start by mapping the working keys, this will help understand the matrix/pattern..

This is not exactly that, but something similar, compare to see if this helps..

https://medium.com/@monkeytypewritr/building-your-own-keyboard-from-scratch-bd0638c40850

The white schematic shows standard keyboard layout... compare them with the key placement, if all the non working keys somehow connect with each other, the issue might be elsewhere..


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## tech_no (Jun 12, 2007)

Hi tristar

I have finished the key mapping of my whole keyboard now. It has taken a long time as I have gone through each key in turn and then tested continuity for each key. I have enclosed a pdf. of my findings.

Hope you can make sense of my written chart, I couldn't see a way of typing some of the keys.

Thank you for posting the PCB layout diagram; there are similarities in the way it is connected. My keyboard has more keys being a full keyboard and a different layout for the same keys in some instances.



I need to point out that the Shift (R) key, being a longer key, has a support between the PCB and steel chassis. You are probably aware that such keys have 3 sets of soldered terminals although only the middle set is the MX switch. On the keyboard the two left hand terminals are marked as Shift (R) and when I have said that keys are joined to this switch, in my chart, both of those terminals are continuous. However the right hand one isn't, the one marked K56. The odd thing is that the K56 terminal is continuous with a whole set of keys and when this key is continuous the other two terminals are not. There is no MX switch in this K56, just a hole, for the support on the other side. I have attached a photo of this Shift(R) key showing the K56 terminals (Photo 1). Hope you can understand what I am saying. Is this normal?

The components you think are possible diodes. They are copper colour with one black band on each. They are hard, such as metal (don't think they are glass). I have attached two photos of them (photo 2 and 3). Hope you can see them. Tested all of them and none are continuous from either way around. However they all have a resistance reading of 4.7 M ohms. Can you say what they are from this kind of large resistance?

Could you let me know what I need to do next. I can test the keys not working by holding a wire on the positive terminal and connecting to each key that is continuous to it. I expect though that the non working key will take on the letter/number of the other key, as it did before. If this is the case is there any other way to save the keyboard?


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## tech_no (Jun 12, 2007)

Could the components in the photographs above be miniature coils? The shiny surface is a varnish maybe over a copper coil?

I have tried to find such like components online and have found this one:

https://benatav.com/products/miniature-rectangular-coil/

Anyone know if this could be the case?


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## tristar (Aug 12, 2008)

That definitely is a Zener diode, (one way full continuity, the other way will be no continuity, however that is displayed as very high resistance) a coil will show 2 way connectivity, since it's nothing but a continuous wire and there will be no polarity.

The SHIFT Key will have additional connectivity, since holding down the SHIFT Key alters the function of the other keys.. This might be the same for other keys as well which take on multiple roles..

You might find additional components missing from the board, since the design is built keeping in mind enhancements. So there could be a variant of the same keyboard with let's say for argument sake a browser key, this might power that...

The grid looks good, and I really appreciate your perseverance and commitment on this...

Which of the keys are not working, and what is common to all of them or the majority of them ?


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## tech_no (Jun 12, 2007)

Hi tristar

Thank you for your reply. I am glad you recognize the components as Zener Diodes. I can get no continuity on these components as stated before. I have tried the probes both ways and even pushed a bit and scraped a bit with the probes on the connections but definitely nothing. The resistance reading was taken on the same connections and that can be taken one way only; positive at the top. I wouldn't have thought they are all dead with most of the keyboard working.

I can understand what you mean about the Shift Key having two functions. Are you saying the K56 terminal on the Shift Key, that is continuous with a whole row of keys, could be for a key that is not used on my model board?

I have attached a photo of my keyboard with a red ring around the keys not working. None of them are joined to each other (i.e. not on the same line on my grid). They are all near the end of a grid line but this is because it is in the area of the water spill.

What we know is that all keys have been found to be continuous when tested separately. The grid covers all keys so I would think the traces are OK to them. The lack of the continuity in the diodes seems very odd as each key has a diode and most of the keys are typing OK.

The keys not working are:

Top zero key-line 2 on the grid.
The P key-Line 3 on the grid.
;: key-line 4 of the grid.
.> key-line 5 of the grid.
Return (otherwise known as Enter key)-line 7 of the grid.
Down arrow key_line 8 of the grid.
0 key on numerical keyboard-line 10 of the grid

All of the above keys don't work with their second function either, using the Shift key, if they have one.

I am not sure if some of the F keys are working. Keys like Fn or End or Pause Break or Scroll Lock I am not sure how to use or test?


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## tech_no (Jun 12, 2007)

tristar, I can take a photo of the onboard micro-processor that shows a line going to each part of the keyboard with a letter or abbreviations written against each line on the PCB.. I don't know if this would help you or mean anything to you?

There is a circuit diagram above that kendallt has posted that looks very much like it.


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## tristar (Aug 12, 2008)

The 4 keys in the middle in a straight line are probably connected together in a way, finding the end connectivity and fixing that should bring the keys back up...

To the best of my knowledge those look like zeners, here's something that will help you test the zener...

How to Test a Zener Diode

Can you check the keys in the same line as the P key line vertically, the 9 key and the line of keys below, test the connectivity both in the row and column connectivity to see how they're set up and where they connect to..

Also, see if you can locate a small chip/IC on the board, because the key control will be fed to that IC to control the functions of those keys.. Check the legs of the IC/chip to see if there are any residual oxidation left on the legs..


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## tech_no (Jun 12, 2007)

tristar, 

The link to test the Zener Diodes doesn't work.

I have tried two browsers with the same results.


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## tristar (Aug 12, 2008)

Copy the link, paste it in a new tab, remove the *https://* from the link and hit enter


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## tech_no (Jun 12, 2007)

Thank you tristar.

Just been testing each key that doesn't work for the continuity to the legs on the chip. Each key connects to different legs on the chip. 

I can see no oxidation at all on the legs of the chip even with a magnifying glass.

There are two capacitors on the key switch side of the PCB, they have vastly differing resistance but not sure if my multimeter can test for capacitance. In farads isn't it?

I cannot seem to follow the traces from the chip to each key not working.


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## tech_no (Jun 12, 2007)

I have the link working now for the diodes


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## tech_no (Jun 12, 2007)

Just tested the Zener Diodes for resistance. Something seems wrong here.

Black probe to black stripe is giving a resistance of: 1.5 M ohms

Red probe to black stripe is giving a resistance of: zero.

No continuity either on any of them.

It seems the higher resistance should read the other way around.

Does the voltage test need to be done with the USB connected to the keyboard?


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## tech_no (Jun 12, 2007)

tested Zener Diodes for voltage DC with USB not connected.

Black probe to black stripe: 0.04 V

Red probe to to black stripe: 0.006-0.012 V


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## tech_no (Jun 12, 2007)

The keys not working will only connect to those I have mapped in my grid. I spent a long time continuity testing every key on the keyboard for each key I tested. All of the keyboard was tested.

I have re-tested though as you have asked me to tonight and no other keys connect to the keys not working save for the ones mentioned on the grid.


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## tristar (Aug 12, 2008)

Does this happen with all the diodes on the board ?


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## tech_no (Jun 12, 2007)

Hi tristar

I have just put a new battery in my Fluke 114 multimeter and took the voltages on every Zener Diode on the keyboard. Unfortunately, I still get the similar readings.

Red Probe to black stripe on diode: 0.01V min. to 0.07V max.

Black Probe to black stripe on diode: -0.006V min. to -0.05V max.


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## tech_no (Jun 12, 2007)

Just tested every Zener Diode for resistance. These are my results:

Black Probe to black stripe on diode: All around 1.53 M ohms.

Red Probe to black stripe on diode: All zero resistance except 3 diodes on the top row, they are reading: 2.3 M ohms.

All of the diodes have no continuity in either direction.


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## tech_no (Jun 12, 2007)

I am right in taking all of these readings without the keyboard connected via USB?


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## tristar (Aug 12, 2008)

Yeah.. But are you doing continuity test ? if so, then you're doing it right, you should get readings.. But chances that 'All' of them failed are very remote, so we probably should move forward with the assumption that they're probably fine.

Can you test the chip to the key matrix and map them ?


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## SpywareDr (Jun 15, 2013)

Fluke.com > How to test diodes


> Digital multimeters can test diodes using one of two methods:
> 
> 
> Diode Test mode: almost always the best approach.
> ...


...


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## tristar (Aug 12, 2008)

Thanks SDR


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## SpywareDr (Jun 15, 2013)

:thumb:


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## tech_no (Jun 12, 2007)

Thank you for the info SpywareDr on how to test diodes. My Fluke multimeter (114) is the first priced one for basic electrical tests only. I have no diode or capacitance test. I would have to use the resistance test but it looks like I am getting false readings due to the diodes being attached to the PCB.

I put a new battery in tristar just in case it was that causing the no continuity readings on the diodes but it turned out to be not the case.

I have mapped the microchip to the keyboard lines. I have attached a very rough drawing. Please refer to my keyboard lines I have mapped previously.
I cannot read what is written on the chip even with my magnifying glass. The writing has faded but my eyes need testing too :uhoh:

By the numbers I can make out I think the chip is something like this: 

https://www.nxp.com/products/proces...am-ethernet-usb-lqfp100-package:LPC1769FBD100

I can read NXP

There are so many legs very close together it is hard to count how many but I think 60.


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## tristar (Aug 12, 2008)

You have to check connectivity from the chip to the key matrix to see if you're able to figure out the tracks/traces.. Basically track the key from the contact points back to the MP/chip...


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## tech_no (Jun 12, 2007)

tristar, that's exactly what I have just done. My sketch shows which lines of my matrix connect to which pin of the chip.

I tested every key on a matrix line to a particular leg.

A line of a matrix connects to one leg on the chip.

Whatever way could I do it? I must be missing the method.

Can you tell me how to do it please?


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## tristar (Aug 12, 2008)

Nope, that's correct...

Are you able to trace the connectivity lines to all the keys ? atleast till the diode ?


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## kendallt (Feb 21, 2007)

tristar said:


> Nope, that's correct...
> 
> Are you able to trace the connectivity lines to all the keys ? atleast till the diode ?


 I don't think he can without access to both sides of the board. In the pics you can see many 'dead end' traces with solder pits at the terminus, that indicates a double sided board with another trace you can't access.


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## tristar (Aug 12, 2008)

Yeah, he has access to both sides, he needs to hold the board vertically, put the lead on one contact and trace it to the other contact on the other side of the board...


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## tech_no (Jun 12, 2007)

tristar, as I mentioned earlier in this post, I cannot use the probe to slide along the traces. They are not conductive on this side of the PCB. I wish they were.

kendalt, thank you for pointing out that this isn't possible to follow the traces on this side of the PCB. I think you are right.

tristar I think you have forgotten that the other side of this PCB is inaccessible. Please refer back to my photos and description of how the MX Cherry switches are clipped into a metal chassis when the keyboard is manufactured. The posts of the switches are soldered to the PCB together with its other components once the chassis has been slid into place sideways and held by its hooks (please see photo). The hooks are soldered in some places to earth and lock the PCB.

The only way to gain access to the other side of the PCB is to de-solder every switch together with the light diodes (which are part of each switch) and each Zener Diode etc. Once all the components are de-soldered and the hooks (sticking up in red in the photos) de-soldered then you can move the PCB sideways so that it un-slots from the PCB.

I can see traces on this side of the PCB but are they just for visual aids or are those the conductive lines under a heavy varnish (or whatever medium is sprayed onto these boards? I am inexperienced in electronics so don't know.

Is the keyboard impossible to repair?


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## tristar (Aug 12, 2008)

Sorry, I must have missed the part..

Unless you can have access to the PCB, it's going to be difficult to figure out what goes where... I'd recommend to pack it and send it in for an Out of warranty support repair..

I was wondering why it's so difficult to trace connectivity, but looks like limited to one side of the keyboard is the challenge..

One last shot, can you shoot a video on your phone of the entire setup and upload to youtube and point the places which are connected, You shouldn't have to disconnect all switches and components to see the other side of the PCB, it doesn't work from a service standpoint..


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## tech_no (Jun 12, 2007)

No problem tristar. I have learned quite a lot from this post.

I was wrong about everything having to be de-soldered to remove the PCB from the metal chassis. Each LED diode has to be removed as they are sat on top of each key and each MX switch has to be removed. Apart from that it is only the solder locking the PCB to the metal lugs on the chassis. All of the other components are soldered to the PCB itself so wouldn't have to be be removed.

I am certainly thinking of doing this when I have time. It is worth saving the switches and LED diodes if not anything else. If I unhooked the PCB from the chassis I would try to follow the traces to each key not working. If you can't leave this post open I could open another later on or pm you with my findings.

I don't think it's worth paying out for a repair. I think the money is better spent on a new one.

I don't need to go on Youtube either as I know the above info from an expert's review on my keyboard. He said the only drawback with the keyboard was if you ever need to repair it as it is made in a way as every LED and switch has to be removed to gain access to the back of the PCB. I was trying to find it last night so I could have included the link but unfortunately couldn't.

Thank you very much tristar and everyone else who helped me with your comments. The work you people do is very much appreciated.


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## tech_no (Jun 12, 2007)

Does anyone know how to remove the Space Bar plastic key?

Removed all other keys with the special puller but this one will not budge.


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## SpywareDr (Jun 15, 2013)

Start at about 0:29 in this video: 








?


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## tech_no (Jun 12, 2007)

Just realised something, which makes this job impossible even with the PCB removed from the chassis.

I was reading last night on another review of this keyboard that the PCB is a dual layered one. I never knew what this implied but looking into a small gap with a torch you can see that the other side of the PCB is the same as this side with non conductive traces. I am guessing the traces are buried between each board?

It can never be tested if this is the case.


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## tech_no (Jun 12, 2007)

Thank you SpywareDr for the video on the spacebar.

Mine hasn't a wire. It is is held on sprung supports each side, similar to the key itself. You cannot tilt it either. Seen a video on removing allof the keys on my keyboard in fast motion and he pulls this key off the same as the others. Seems very hard and don't want to break it.


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## SpywareDr (Jun 15, 2013)

From what I'm reading on the 'net, a dual-layer PCB helps reinforce the solder joints and maintains that solid feel when typing.


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## SpywareDr (Jun 15, 2013)

Oops, sorry about that. Looks like you pull each end up gently, then the center. Start at about 4:20 in this video:


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## tristar (Aug 12, 2008)

Sorry we couldn't fix further, most pcbs are not single and have multiple layers of connectivity within them.. however they would have to meet at a point where they contact at either side of the PCB which is visible to you..

You might see a single dot on the board that does not connect anywhere, that is one end, the other end would travel within one of the sandwich layers and then pop up at another point on the board.


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## kendallt (Feb 21, 2007)

In post 16, you have a picture with red circle and a plus sign, directly below the circle and to the right are the 'dead end' traces that show the small dimples that are the connections for the different layers. They add more layers depending on the complexity of the circuits, 8 and 12 layer boards are fairly common. 

Can normally use an exacto type knife to carefully scrape the varnish off the traces to check continuity, when done, clear nail polish works as a repair coat. 

If you do decide to tear it apart to get to the other side, pick up a solder sucker because you'll need to have every switch loose before you can lift it out of the red cover.


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