I don't know where to ask this question, so I will ask it here... Please tell me to take it somewhere else if it is not a simple question.
A friend of mine at the office has been using my QFR with blues. Today he showed me that some of the key presses are not registering. The ones that are really noticeable are: 5, t, b and left alt. I noticed right away that 5, t, b are probably on the same matrix line. Left alt is another story, but that key gets used a lot because he is using the keyboard on a mac (so its his command key).
So to the question. How do I troubleshoot the problem? I am guessing there is a problem with a couple solder joints are something like that. It works a lot of the time, but periodically it misses a key press. Some of those keys are worse than others. Should I unsolder those switches and then resolder them and see if that fixes the problem? Anything I can test with a multimeter which would help diagnose where the problem stems from?
Figured I would post back for other peoples benefit on this one...
I checked and I was past my warranty by about 2 weeks, so I opened it up to see if I could fix it. I have to say I was not impressed with what I saw. I don't think I saw a single shiny solder joint, they were all a matte grey. Before I opened up I checked and I had about a 10% hit rate on B and about an 80% hit rate on 4 other keys. I solder pulled the 5 bad keys so I could flux and resolder them to see if that would fix the problem. Of the 5 switches I unsoldered, 2 of them had pad issues. One pad lifted and was broken, but I was able to gently put it back in place and with a crap ton of flux was able to get a nice solder joint on it. The other was a different story altogether. When I first looked at the joint I kinda scratched my head and thought 'that looks funny'. It was like there was a small air hole on one side of the solder joint. I thought, 'whatever, its a crap solder job, I will just resolder it'. I solder pulled it and realized that not only was the pad broken, it was missing a piece. That is why it looked like it had an air hole because there was no pad on the hole, so the solder did not spread to that side of the hole. Obviously, with only half a pad, I really lifted that pad. I was able to wrap the pad back around the switch leg and solder it back on, but it was ugly. We will see how long it lasts...
All to say, I am VERY disappointed with the quality of this QFR. I have no idea how something like this gets through QC. I have no idea how so many people have modded a QFR. How many of you had to do some direct wiring after unsoldering it?
Anyway, to make a long story short(er), resoldering the switches fixed the problems with all the switches, so it is back to good (for now). I know I am going to have to resolder a bunch more switches after seeing that solder job, but I don't want to just do them all right now because of how bad the pads are. This is probably going to be one of those boards I just fix slowly as it breaks.
Thanks for all the suggestions on this...