Strange keyboard behavior after soldering in new switches

[esylvester]

Hello,

I'm looking for some insight into what went wrong or generally what is wrong with this board.

My best theory is that I messed something up while soldering in new switches. I tested EACH key after I desoldered the whole board using the same tester, and everything worked just fine. So nothing got messed up in the desolder process. I can't physically see anything on the backside of the PCB that could be causing this issue. Each solder point appears just fine, and the board doesn't show any signs of damage to any SMD. I have desoldered and soldered many boards in the past. Not to say that makes me invincible to breaking a board, but I do have experience in this case. This is actually the second Masterkeys Pro S that I have desoldered and soldered in new switches. Regarding software, I have tried everything I can find online. I have done all the "reset" and "erase" functions. Nothing changes the behavior of the board.

Thanks

[suicidal_orange]

The grid pattern shows that you have a short, the Filco matrix has the keys connected in U shaped columns so it's every other key that activates.  The fun with R looks to be it seeing the windows and/or alt keys pressed...

Edit: Just looked again and it's not in a case so shouldn't be a cable crushed under the pin as I first thought.

[esylvester]

Thank you for your thoughts. I've attached pictures of the PCB. I've closely scanned this board back and forth with my eyes looking for any solder that might be contacting something. I can't find anything.

[suicidal_orange]

What's with the switch next to the USB cable socket?  Looks like both pins are shorted to square pads next to them labelled R and +.  Maybe they're supposed to be but that looks weird to me.

[esylvester]

Yeah that struck me as a problem as well. I figured out that those pads are designated to LEDs. I've desoldered that switch and made sure those pads made no contact. This did not change any of the behaviors.

[esylvester]

FIXED!!! I FIXED IT! I FOUND THE SHORT!

[Maledicted]

FIXED!!! I FIXED IT! I FOUND THE SHORT!

That's awesome to hear. What the heck was behind that tiny blob, in the middle of nowhere, causing a short?

[suicidal_orange]

The stray blob of solder melted through the mask and shorted the traces?  That is unlucky.  Well done for spotting it, any further up and/or right you'd have had no chance )

[esylvester]

Update

Okay, now I am just dumbfounded. So the keyboard worked 100% after I removed that blob of solder. I did like 3 successful typing tests and suddenly it relapsed back to its old behavior. I am so confused.

[Leslieann]

Check that you are not pushing pins into the cord.

This is often how it reacts when that happens, works fine then they slowly bite into the cord. It can be extremely hard to spot so look carefully and/or wrap it in electrical tape, that will reveal it better.

[esylvester]

I don't believe this is the problem. I've held the board up so the cable was making no contact with anything, yet the problems persist.

[esylvester]

Update #2

Okay, I have been obsessed with fixing this keyboard. I desoldered the whole board and cleaned off all of the flux. Today I decided to try something different. I baked the PCB in the oven. I set the temperature to 385 and cooked it for 10 minutes. Lo and behold, it works again !! I let it cool down for a while and tested it using tweezers. Everything appears to be functional! Cheers to the oven method.

[pixelpusher]

What keyboard is in the back at 0:15?




Hope it stays fixed!

Wait, is that just a norbatouch?  Ha.  I thought it was like copper color with a white inlay.  I think now it's just the lighting.

[esylvester]

What keyboard is in the back at 0:15?

(Attachment Link)


Hope it stays fixed!

Wait, is that just a norbatouch?  Ha.  I thought it was like copper color with a white inlay.  I think now it's just the lighting.

Hah yeah its a Norbatouch! The keyboard inside is Masterkeys Pro S with Box Navies. The keyboard I made this post for is another Masterkeys Pro S. Now I can switch between Box Navies and Box Blacks. One day I'll find another Norbatouch case.

[Maledicted]

Update #2

Okay, I have been obsessed with fixing this keyboard. I desoldered the whole board and cleaned off all of the flux. Today I decided to try something different. I baked the PCB in the oven. I set the temperature to 385 and cooked it for 10 minutes. Lo and behold, it works again !! I let it cool down for a while and tested it using tweezers. Everything appears to be functional! Cheers to the oven method.

Nice, always worth trying if the next alternative is a dumpster. I have baked many a PCB myself. I'm glad this one worked out.

[typo]

When this happens it is an issue of impedance, If you can figure out where the short is, which may be invisible to the naked eye. You can clean it with flux. This is the reason it is so discouraging because often there is nothing you can see. By putting it in the oven you simply "sweated" away any traces inducing the impedance mismatch. Since they are tiny they just boil away and vaporize in seconds. It can even be flux itself.

[Maledicted]

When this happens it is an issue of impedance, If you can figure out where the short is, which may be invisible to the naked eye. You can clean it with flux. This is the reason it is so discouraging because often there is nothing you can see. By putting it in the oven you simply "sweated" away any traces inducing the impedance mismatch. Since they are tiny they just boil away and vaporize in seconds. It can even be flux itself.

I'm lazy. I test things with the flux still on. No idea if it is meant to be no clean or not, lol. I haven't fried anything though. Are you suggesting tin whiskers, perhaps? I wouldn't think you would have much to worry about on keyboard pcbs, where most of the contacts/pads are pretty far away from each other.

[jseyfert3]

I'm lazy. I test things with the flux still on. No idea if it is meant to be no clean or not, lol. I haven't fried anything though. Are you suggesting tin whiskers, perhaps? I wouldn't think you would have much to worry about on keyboard pcbs, where most of the contacts/pads are pretty far away from each other.

My understanding is that in general for many things a bit of flux isn't going to cause an issue, especially things like keyboards that aren't operating at high frequencies and whatnot. The main issue is that flux is often acidic to some extent, and depending on the PCB/components/flux/conditions what can happen is flux that isn't cleaned can cause corrosion and failure later on down the road. The most common sort of flux in hobby type solders is rosin. This is fairly mild stuff and often doesn't cause issues down the road if not cleaned. Other types of flux can almost certain cause issues later if not cleaned off. Best practice is to always clean flux off after soldering, but I've soldered a number of things with rosin core solder, not cleaned them, and they're still functioning years later.

In a lot of commercial settings, my understanding is they typically use water soluble flux (rosin flux is not water soluble). They then run the soldered boards through a PCB washer. Essentially this is a glorified dishwasher that usually washes them with deionized water (alternatively these machines could use chemicals for non-water soluable flux). In fact, some components, such as buzzers, actually come from the manufacture with stickers over the hole. The purpose of these stickers is to keep water or cleaning chemicals out of the buzzer when it goes through a board washer after soldering.

TL;DR: For hobbyists, not cleaning flux usually isn't a problem, but in industry it is usually always done.

[Maledicted]

I'm lazy. I test things with the flux still on. No idea if it is meant to be no clean or not, lol. I haven't fried anything though. Are you suggesting tin whiskers, perhaps? I wouldn't think you would have much to worry about on keyboard pcbs, where most of the contacts/pads are pretty far away from each other.

My understanding is that in general for many things a bit of flux isn't going to cause an issue, especially things like keyboards that aren't operating at high frequencies and whatnot. The main issue is that flux is often acidic to some extent, and depending on the PCB/components/flux/conditions what can happen is flux that isn't cleaned can cause corrosion and failure later on down the road. The most common sort of flux in hobby type solders is rosin. This is fairly mild stuff and often doesn't cause issues down the road if not cleaned. Other types of flux can almost certain cause issues later if not cleaned off. Best practice is to always clean flux off after soldering, but I've soldered a number of things with rosin core solder, not cleaned them, and they're still functioning years later.

In a lot of commercial settings, my understanding is they typically use water soluble flux (rosin flux is not water soluble). They then run the soldered boards through a PCB washer. Essentially this is a glorified dishwasher that usually washes them with deionized water (alternatively these machines could use chemicals for non-water soluable flux). In fact, some components, such as buzzers, actually come from the manufacture with stickers over the hole. The purpose of these stickers is to keep water or cleaning chemicals out of the buzzer when it goes through a board washer after soldering.

TL;DR: For hobbyists, not cleaning flux usually isn't a problem, but in industry it is usually always done.

I do almost always clean the flux off, once I know for sure that I'm done soldering. I just leave it on while I'm still testing/tweaking. I should really get some water soluble flux, or "no clean" flux. I usually clean it off with at least some isopropyl alcohol. If that doesn't work well enough, I'll let some goo gone soak in for a few minutes, rub as much off as I can, and clean that up with isopropyl, just like I do with stubborn thermal paste.

Interesting tidbits about manufacturing though.

[jseyfert3]

I'm lazy. I test things with the flux still on. No idea if it is meant to be no clean or not, lol. I haven't fried anything though. Are you suggesting tin whiskers, perhaps? I wouldn't think you would have much to worry about on keyboard pcbs, where most of the contacts/pads are pretty far away from each other.

My understanding is that in general for many things a bit of flux isn't going to cause an issue, especially things like keyboards that aren't operating at high frequencies and whatnot. The main issue is that flux is often acidic to some extent, and depending on the PCB/components/flux/conditions what can happen is flux that isn't cleaned can cause corrosion and failure later on down the road. The most common sort of flux in hobby type solders is rosin. This is fairly mild stuff and often doesn't cause issues down the road if not cleaned. Other types of flux can almost certain cause issues later if not cleaned off. Best practice is to always clean flux off after soldering, but I've soldered a number of things with rosin core solder, not cleaned them, and they're still functioning years later.

In a lot of commercial settings, my understanding is they typically use water soluble flux (rosin flux is not water soluble). They then run the soldered boards through a PCB washer. Essentially this is a glorified dishwasher that usually washes them with deionized water (alternatively these machines could use chemicals for non-water soluable flux). In fact, some components, such as buzzers, actually come from the manufacture with stickers over the hole. The purpose of these stickers is to keep water or cleaning chemicals out of the buzzer when it goes through a board washer after soldering.

TL;DR: For hobbyists, not cleaning flux usually isn't a problem, but in industry it is usually always done.

I do almost always clean the flux off, once I know for sure that I'm done soldering. I just leave it on while I'm still testing/tweaking. I should really get some water soluble flux, or "no clean" flux. I usually clean it off with at least some isopropyl alcohol. If that doesn't work well enough, I'll let some goo gone soak in for a few minutes, rub as much off as I can, and clean that up with isopropyl, just like I do with stubborn thermal paste.

Interesting tidbits about manufacturing though.

Two other things of note. When writing my previous post, I did a quick Google search to back up my memory and I found references on electronics forums to no-clean flux possibly causing more issues that other types of flux (generally impedance type issues in high frequency applications), and being the hardest to clean off if it did cause issues and you wanted to clean it off. Not sure how much data there was to back that up though.

Water soluble flux, while it can be cleaned with water which is nice, needs to be cleaned as I understand because it is highly likely to lead to corrosion if not cleaned off properly. I've seen this requirement for cleaning in many different locations, so I personally would not skip cleaning if you went the water-soluble route. I've thought about going to water soluble flux myself, and I personally would never skip cleaning if I used it due to things I've read, even though I do skip cleaning most of the time with my rosin core solder I currently use. Testing before cleaning is probably just fine, it's just that it would lead to corrosion in the future if not cleaned.

[Maledicted]

Two other things of note. When writing my previous post, I did a quick Google search to back up my memory and I found references on electronics forums to no-clean flux possibly causing more issues that other types of flux (generally impedance type issues in high frequency applications), and being the hardest to clean off if it did cause issues and you wanted to clean it off. Not sure how much data there was to back that up though.

Water soluble flux, while it can be cleaned with water which is nice, needs to be cleaned as I understand because it is highly likely to lead to corrosion if not cleaned off properly. I've seen this requirement for cleaning in many different locations, so I personally would not skip cleaning if you went the water-soluble route. I've thought about going to water soluble flux myself, and I personally would never skip cleaning if I used it due to things I've read, even though I do skip cleaning most of the time with my rosin core solder I currently use. Testing before cleaning is probably just fine, it's just that it would lead to corrosion in the future if not cleaned.

That's good to know about no-clean flux, but I have always been aware of the dangers of corrosion when leaving flux residue behind. I don't think anybody would bother getting water soluble flux and then leave it on there anyway. This reminds me that I need to stop being lazy and open every single one of my original Xbox consoles and remove their clock capacitors before they leak and start eating the PCB.

[esylvester]

Just a quick update:

The keyboard relapsed back to its old behavior. I've decided to give up on the poor thing. Luckily I found someone selling a new Masterkeys Pro S. Back to desoldering this board for the third time to harvest my beloved switches.

[typo]

Bro, it is not so hard. No need to desolder all. What I told you. Use a multimeter and find the impedance drop off. Unless it is just too frustrating already I get it. The Master keys is a nice board but wouldn't you like something nicer. Or is cash an issue? I totally understand if it is, you do not even have to say. Master keys is plenty good. You might try to get a used Topre if you like that. you would ultimately never have this issue again.
Any MX board is prone to issues due to the sheer amount of solder junctions involved. It is at the mercy of whom put it together. I have had one after the other go bad. Never a Topre. I am sorry for your misfortune. My sorry self has maybe a few hundred dead boards because of this very thing. The only way you "might" do better with a MX board is with a custom or certainly with a DIY kit as long as you trust yourself.

[esylvester]

Bro, it is not so hard. No need to desolder all. What I told you. Use a multimeter and find the impedance drop off. Unless it is just too frustrating already I get it. The Master keys is a nice board but wouldn't you like something nicer. Or is cash an issue? I totally understand if it is, you do not even have to say. Master keys is plenty good. You might try to get a used Topre if you like that. you would ultimately never have this issue again.
Any MX board is prone to issues due to the sheer amount of solder junctions involved. It is at the mercy of whom put it together. I have had one after the other go bad. Never a Topre. I am sorry for your misfortune. My sorry self has maybe a few hundred dead boards because of this very thing. The only way you "might" do better with a MX board is with a custom or certainly with a DIY kit as long as you trust yourself.

I enjoy Topre, I used a Leopold FC980C for a long time. Hah that board got me through college. I lean towards MX boards for the sheer variety out there. That's what I love about the Norbatouch, how it accepts the Masterkeys. Money isn't exactly the issue but it is definitely a big factor. My Norbatouch is essentially my end-game. However, because there is no such thing as "end-game", here I am ordering new Masterkeys to satisfy my urge for something new. I love Box Navies, but I also love heavy linear switches, so my idea was to have two boards with different switches that I could swap in and out of the Norbatouch.

I have desoldered and soldered boards without issue. Can't say I am an expert, but I do have the experience and have the proper equipment.

Only other board I have my eyes on is the Satisfaction 75... That is certainly another end-game right there. Hah

[Maledicted]

Bro, it is not so hard. No need to desolder all. What I told you. Use a multimeter and find the impedance drop off. Unless it is just too frustrating already I get it. The Master keys is a nice board but wouldn't you like something nicer. Or is cash an issue? I totally understand if it is, you do not even have to say. Master keys is plenty good. You might try to get a used Topre if you like that. you would ultimately never have this issue again.
Any MX board is prone to issues due to the sheer amount of solder junctions involved. It is at the mercy of whom put it together. I have had one after the other go bad. Never a Topre. I am sorry for your misfortune. My sorry self has maybe a few hundred dead boards because of this very thing. The only way you "might" do better with a MX board is with a custom or certainly with a DIY kit as long as you trust yourself.

I'm still not sure how you keep encountering so many problems with solder joints. I have a bunch of boards that are older than I am that are 100% original with no repairs that work like new, even my Unitek K151Ls had 100% function when I got them, and Unitek does not have a good reputation for quality.

Only other board I have my eyes on is the Satisfaction 75... That is certainly another end-game right there. Hah

Agreed. I want one of those keyboards some day. They should really see mass production.