… or did I just make poor looking molded keys?
The case of an unrefurbishable(lolwurd) C116
Fast forward few weeks and String of Agenda (DemoScene group) bought that C116 from Kaz. He lives not so far away from me so one day he’d asked me if I could have a look at his C116 and maybe work on it a bit because OBVIOUSLY, it was dead and also obviously I was like HELL YEAH.
Guys from Agenda create awesome demos as you can see on Pouet so I was like … of course, I will have a look at it and help out my fellow demosceners 😀
It took me a while to figure out how wrong I was 😀
A lot was broken in this Commodore but let me start from … the start? 😛
A keyboard PCB in a C116s is held by plastic poles that are melted after mounting. It is built as a piece that wasn’t meant to be ever disassembled. Someone figured out that metal wires can replace original design by simply melting ’em into keyboards case. The idea itself was great but … the temperature used by original modder was a bit too high resulting in a lot of charred plastic.
Another problem that I’ve found was an “upgrade” of graphite pads that was supposed to sort out contact problems.
Well, maybe it worked at the very beginning but definitely stopped working with time. Here is why:
LM7805 voltage regulator had some issues sticking to a mobo and that was one of the first things that I’ve repaired in order to check what is really going on with this machine. Without supplied voltage, not much can be diagnosed or can it? 😀
String told me that he’d desoldered some weird mod from this PCB near RF modulator area so next step was to fix traces and install original modulator which I’ve borrowed from a dead C16 motherboard since it shares the very same design
TED chip was tested in another machine so I was sure that it works, but I didn’t have a working CPU. Instead, I’ve installed a 6510 from Commodore 64 with an adapter and hacked ROM.
With a working CPU onboard, I’ve run it and got this.
I had a cunning fixing plan on my mind but first I needed to create a mold.
Apart from the obvious mistake with trapped air bubbles caused by wrong pouring method, it also turned out that I didn’t clean rubber pads properly so all dirt was now perfectly transferred to a mold lol.
So I’ve run some tests with these new keypads armed with conductive rubber and it turned out it worked OK, but to my surprise, original pads didn’t work at all … at least majority of keys didn’t work.
U-bent copper wires were nicely corroded and were covered with copper oxide(black color).
My plan was to remove U-bent wires and glue on brand new conductive pads that were bought as a replacement to TV remote 🙂
Keyboard story continues
If you think that was it then you are seriously wrong lol.
My test setup below revealed that a lot of keys didn’t work at all.
Actually, some columns didn’t work and it looked like some address lines are broken.
… but still, some keys didn’t work …
I was like …
I’ve managed to narrow a problem to a few keys. Damage made by wrongly chosen sandpaper was a direct cause of it. A guy who tried to sand it before me simply destroyed some traces on a PCB and I didn’t notice it at first.
I’ve assembled a keyboard and run some tests again but unfortunately, some keys stopped working again so still that is not the end of this mess yet 😀
Finally, the whole keyboard started to work! Phew! 😀
It wasn’t the greatest job ever. I will have to work more on my knowledge of various coloring agents and pigments. However, In general, I am happy that another machine is working again 🙂
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