exxos's Atari, Amiga & retro forum

Been working on this for a customer, said his TT would just randomly shut down with a 'wheeee' noise and then refuse to turn on. Sent it to me and under testing sure enough it would turn on for 5 seconds and then shut down. Wasn't sure exactly to the cause so I started with a full re-cap, which didn't fix the problem.

After inspecting the underside of the PCB I noticed the usual track cut from the factory wasn't 100% done properly, so I cut the trace fully and retested. But no it still showed the same behaviour.

I then suspected the opto-isolator because I've read that the trace cutting is somehow related to it, so it's possible it could have died due to the trace not being cut properly. So swapped it out for the proper Sharp pc-111 (because it had the 'bad' type) and voila, it now works perfectly :)

Before re-cap:


After re-cap:


The almost-cut trace:


Swap opto-isolator:


New opto:


+12v:


+5v:


-12v:

Thank you so much for an excellent job, first class fast service and good comms.
Cheers sir

Nice one, and you've just reminded me, I think need to order opto isolators for my Mac Classic.