Model F Keyboard Fixed

[profdc9]

I wanted to share an experience that I had.

I have a 5160 PC XT and a Model F keyboard. The Model F keyboard always acted flaky, and I noticed that if I bent the circuit board backwards the keyboard would work for a while, but then produce 301 POST errors and stop working.

I even made the mistake of taking off the back and having all of the little keyflaps fly around everywhere. It took two hours to put them back in place and slide the back on. Don't do this. Also, the black sheet inside the keyboard basically disintegrated when I did that.

Finally, I decided to throw caution to the wind and reflow every single solder joint on both sides of the PCB including the vias (but excluding the area underneath the keyboard itself). After doing this, the keyboard started working fine.

So if you find your Model F keyboard does not work, but works when you bend the PCB, maybe you have a cracked solder joint or something like that.

I know this may sound obvious, but it's always a bit risky to be doing a lot of soldering on old, irreplaceable hardware.

 

[RetroAND]

I wanted to share an experience that I had.

I have a 5160 PC XT and a Model F keyboard. The Model F keyboard always acted flaky, and I noticed that if I bent the circuit board backwards the keyboard would work for a while, but then produce 301 POST errors and stop working.

I even made the mistake of taking off the back and having all of the little keyflaps fly around everywhere. It took two hours to put them back in place and slide the back on. Don't do this. Also, the black sheet inside the keyboard basically disintegrated when I did that.

Finally, I decided to throw caution to the wind and reflow every single solder joint on both sides of the PCB including the vias (but excluding the area underneath the keyboard itself). After doing this, the keyboard started working fine.

So if you find your Model F keyboard does not work, but works when you bend the PCB, maybe you have a cracked solder joint or something like that.

I know this may sound obvious, but it's always a bit risky to be doing a lot of soldering on old, irreplaceable hardware.

Did you know there are replacement sheets like the one that disintegrated? This way you could finally restore it.
Be cautious with the SLT present in the controller board, nobody except IBM produced it so if it breaks you would need to cannibalize another Model F, though I am studying it to find a replacement.
The microcontroller is a 8048, can be replaced by 8748/8749 microcontrollers without issues if you burn the correct firmware into them.

I hope some time in the future could bring some "irreplaceable" hardware to be repairable.
Thank you for your post, microcuts are always a serious problem as they are difficult to locate and fix.

 

[andy]

Before you remove the back plate you should first remove all of the key caps (except the space bar). This takes the pressure off the springs so they don't fly everywhere. It's also much easier to reassemble it with the key caps removed (except for the space bar which can't be easily installed when the keyboard is fully assembled).