I've been Coleco'd

[rubber_jonnie]

OK then, so one more RAM IC replaced and back to normal:

IMG20240930141256.jpg (353.42 KiB) Viewed 143 times

Once again spotted using the thermal camera as it had gone cold. Getting quite tempted to replace the lot now, but I'll leave it doing a burn in this afternoon and see what transpires.

EDIT: Audio also works just fine.

[PhilC]

Nice spot there RJ, we all usually concentrate on ram chips getting too hot, so I'll have to remember that one.

[rubber_jonnie]

Nice spot there RJ, we all usually concentrate on ram chips getting too hot, so I'll have to remember that one.

What's interesting is that the 2nd one that died also went cold. Not as cold as the first one, but colder than the rest for sure.

[stephen_usher]

The bias voltages probably burnt something out so there was no more current going through. 4116 chips are really sensitive to the timing of the bias voltages coming up. They also seem to die if left unused for a long time, dying after seconds or minutes. The ones in the TI99/4A that passed through my hands displayed this... The machine worked ine for about 5 seconds and then one and later another 4116 just stopped working.

[HigashiJun]

So far so good !

[rubber_jonnie]

The bias voltages probably burnt something out so there was no more current going through. 4116 chips are really sensitive to the timing of the bias voltages coming up. They also seem to die if left unused for a long time, dying after seconds or minutes. The ones in the TI99/4A that passed through my hands displayed this... The machine worked ine for about 5 seconds and then one and later another 4116 just stopped working.

Have to agree with you, and in fact at power on this morning I'm seeing some more issues:

IMG20241001090230.jpg (148.72 KiB) Viewed 77 times

The writing, AFAIK, should all be black, at least it was yesterday, and it randomly changes when you reset or power cycle. I think I'll just go ahead and replace the rest of the 4116's, I think they are past their best.

[rubber_jonnie]

OK, so the RAM is all good now, at least I hope it is Even if it isn't, I have it all socketed now so swapping out will be a breeze.

I also managed to get the RF shields cleaned up and painted and I'm pretty happy with the results:

IMG20241001223810.jpg (142.25 KiB) Viewed 52 times

So I can start to get things reassembled, though I may wait and sort out the video out first as whilst it isn't bad over RF to my LCD TV, it's not the best either.

Overall looking way better than it did though.

[HigashiJun]

Looks good.

Well done !

[rubber_jonnie]

Looks good.

Well done !

Thanks

Looks like the ColUSB power adapter has been processed in the export centre, fingers crossed it won't take too long to come.

[HigashiJun]

And just hope it will solve some issues too.