• Please review our updated Terms and Rules here

Model 1 Hi-Tek Keyboard Repair

K

ksbex

Member
Joined
Aug 15, 2018
Messages
12
Location
Detroit, MI
I just picked up a Model 1 yesterday. It had a lot of keyboard issues that I've mostly fixed. Cold solder joints were the main problem, but one key had a broken contact in the key switch mechanism. I was able to bend the other contact enough to get the key working but I don't think the repair will last. I can't seem to figure out how to get the switch mechanism apart without damaging it. I've found several sources of info for repairing/replacing a defective key switch on an Alps keyboard but mine is the Hi-Tek model and there are no clips to remove an individual key switch.

This site shows the difference between the models.

https://deskthority.net/wiki/Radio_Shack_TRS-80_Model_I

I'm assuming the square white center unit can be pulled out but I tried with a fair bit of force and it didn't seem like it was going to give and I don't want to break it worse by pulling too hard.

Suggestions?
 
Mine looks like neither of those keyboards. Mine is like a perfboard (two of them, actually, the keypad is a separate board with jumpers going over to the numbers on the main keyboard) that is double-sided taped to the back of the motherboard. It's a mess to work with...
 
The individual key switches on the Hi-Tek can't be removed.

On the Hi-Tek there is a problem I have observed where the solder joins under each key develop cracks over time. When I get one of these in my workshop if the keyboard isn't working properly I look for cracks joins before I start playing with the tines on non-working keys. If I find one cracked joint then I re-solder them all.

Hope this helps,

Ian.
 
Yeah, I had to resolder so many switches that I decided to do them all preventatively. But inside one switch I can clearly see the contact broke off. On one side there are 4 small contacts, on the other there is a single large one. The single large one is broken off. I bent the 4 narrow ones over quite a bit so they still reach the little nub that remains but it seems like it may not hold up. If I could get the white plastic plunger out I might be able to come up with a better fix.
 
You must log in or register to reply here.
Back
Top