Posted By azog on August 27, 2011
So after my last mishap of popping a coil, today a package from Mouser arrived. It had 10 2.2uH coils, and two other special items.
First, when the original coil burned up, it was pretty destructive. It burned out the thru-hole plating, and burned out about an inch of the solder mask. Here is what the solder side looked like after cleaning. I don’t know how well that shows thru, but there is basically no thru-hole plating on the upper hole.
Oddly, the fact that it burned up the solder mask was beneficial, as it gave me a place to make contact. I just folded the leg over and tacked it down.
Now I am DONE with board-work. And when I say DONE, I mean DONE. Again, I’m not certain if the replaced components needed replacing (other than the coil), but just to be able to clean them out is something that puts my mind at ease.
Now, I wasn’t going to spend $0.59 on a handful of coils and spend $12 on shipping. The Mouser catalog had two products which looked promising. First is the Rubber Renew:
I tried this first, as it was the easiest thing to do. Basically just dab a cotton swab into this questionable chemical, and wipe off the conductive keypads. This worked in a /meh kind of way. A lot of keys which were previously unresponsive now came back to life. The few that were still unresponsive actually started to function if I hammered on them to kind of “trigger” them. Once I “triggered” them in that manner, they started to work. I dunno.
I was still unhappy with the response of the keyboard, and the last product I got in the Mouser order was a “Rubber Keypad Repair Kit”.
Now before I get into anything, this needs to be said straight-up:
Anyone who has a Commodore (or other “vintage” computer which uses conductive keypads like this) NEEDS to buy this kit. This stuff is beautiful. It’s a little bit time-consuming, but utterly worth it. It’s made by the same people that make the Rubber Renue.
The basic process is three-step: first, you use the primer on all the keypads. You can see the primer pen in the picture on the left. Let that fully evaporate, about 5 minutes. Then you use super-glue (of all things) on top of all the keypads. Let that dry, also about 5 minutes. The final step is to paint the silver conductive paint on all the keypads. Unfortunately, part way thru the process, the silver pen clogged up, and I had to lop off part of the head. I did not use the whole product, and I re-capped it when I was finished, but I hope it does not evaporate. I don’t currently have a use for it, but One Never Knows, Do One?
See how they’re silver now? They used to be black. You need to let that dry for at least 4 hours, but it’s non-tacky in only a few minutes.
Testing was wonderful. Every single key works, and it feels brand-new. So I bolted everything back together, and experienced the worst thing that anyone who repairs things can experience… It didn’t work! Actually, I knew what was wrong almost immediately:
The caps lock key was shorting out to the chassis… and finally, tada!