OSI 600D Superboard Build

[rubber_jonnie]

Thanks, though I think I may park it and look at it when I'm less annoyed!!!

Yeah, better to cool down before attempting something...

Indeed.

[rubber_jonnie]

OK, so it's been a while, but I spent a little time looking at this machine today and voilå!!!

IMG20251028151647.jpg

IMG20251028151927.jpg

It's fully working again including floppy disks and the additional 24K of RAM:

IMG20251028153827.jpg

The culprits being these two buggers:

IMG20251028153910.jpg

The 74LS04 being U16 and the 74LS138 being from U22.

It's entirely possible that their demise is related to me over-volting the board (8.5v rather than 5v) ages back when I was first building it, and that might hint that more may die down the line.

And before anybody says "those white dots don't indicate pin 1, did you plug them in backwards" no, that's not the case, that goes back to a previous issue when I ended up removing all the ICs and testing them, the white dot indicates they were tested and at the time, were fine. They aren't now.

Nevertheless I didn't have the parts to fix it at CL4. Perhaps it'll work at CL5 :)

In the meantime I'm just happy it's alive again.

EDIT - nearly forgot to mention, I found the faulty chips using my thermal camera as I wasn't getting very far with 'traditional' troubleshooting methods.

[HigashiJun]

:dualthumbup:

[rubber_jonnie]

:dualthumbup:

Very much that 😁

[PhilC]

Happy to see you've got it working once more Jon

[rubber_jonnie]

Happy to see you've got it working once more Jon

Thanks, so am I!

[stephen_usher]

Phew! At least it was just cheap TTL chips.

:dualthumbup: :girldance: :yay2:

[rubber_jonnie]

Phew! At least it was just cheap TTL chips.

:dualthumbup: :girldance: :yay2:

And luckily chips I had in stock 😁