I acquired a Plus/4 a while back, cosmetically pretty, but not working. The only sign of life being the power LED.
With a little reading, I discovered the both TED chip and the CPU both have high failure rates.
While reading I also discovered most of the chips in a Commodore C16 and a Plus/4 are interchangeable. With a working C16, I have a source of 'test' chips.
If you have been reading these forums, you're already familiar with the donor unit.
And the sick Plus/4
The home of the famous TED chip.
The tester in place
With the known working TED chip, still no love, so I put the TED from the Plus/4 into the C16 to test it, No life on the C16 either now, so TED chip from the Plus/4 is dead for sure, but something else is wrong.
Next was to trade the CPU, same results ( but someone didn't take pictures ).
Next, after a little more reading was to try the PLA.
Tester in place.
And now ....
A close up of the culprits.
So now the hunt begins.
There are a few sources for new PLA chips across the internet, the TED chip might be more of a challenge. I've seen a few around, but not on the cheap.
But now I know what's wrong.
Last Edit: Jun 4, 2019 17:42:59 GMT -7 by Blaine: typo
Up and running - VIC 20, C64, C16. Works in progress - Plus/4, C128, Amiga 2000. Looking for - Amiga 2000 Keyboard, C= Colt/PC compatibles.