[HELP] Keys not working after soldering (rebuild)

[Tango38]

Hey guys, so I am rebuilding my TX-87 SE. After using tactile switches for a while I decided switching to linear would be best. I am running into a bit of a problem and I am hoping you can help me out...

So I have all the new switches soldered in, but the A, B, V, and Enter keys don't work. I've tried soldering in different switches with unfortunately no luck.

There are these black resistor things (not sure what they're called) next to each switch labeled "T4". Is it possible the resistors on those keys are bad?

Any help is appreciated!

[suicidal_orange]

Those black things are diodes (or resistors for LEDs...) they could be bad but more likely you just damaged a couple of pads.

Post a pic of the board, if it's black or white try to get the trces showing in the shine but hopefully it's any other colour as it's easier all round.  I will post testing instructions with dots on the pic later if no-one else has

[Tango38]

Those black things are diodes (or resistors for LEDs...) they could be bad but more likely you just damaged a couple of pads.

Post a pic of the board, if it's black or white try to get the trces showing in the shine but hopefully it's any other colour as it's easier all round.  I will post testing instructions with dots on the pic later if no-one else has

I actually found out that during my desoldering I did damage 4 of the pads. So I damaged the right sides, so I found out that I can birdge it to another switch in the same column using a small wire. I am waiting on wire to show up today to test it out. Hopefully I can fix!

[suicidal_orange]

Damn, it's white.  And half of what you want to see is on the other side...

From the little I can make out it looks like the diodes connect the columns so the right pins would connect across the rows, assuming the designer was sane and sober.  I may be completely wrong!

Sounds like you've done some research so you probably know how to test before soldering - good luck and if you have any questions post back.

[Tango38]

Damn, it's white.  And half of what you want to see is on the other side...

From the little I can make out it looks like the diodes connect the columns so the right pins would connect across the rows, assuming the designer was sane and sober.  I may be completely wrong!

Sounds like you've done some research so you probably know how to test before soldering - good luck and if you have any questions post back.

She's back up and running again 😎 appreciate the help!