My Ambika stopped working while I was debugging voicecards :'(

I already opened a thread for voicecards issues somewhere, but this is quite different yet related :

Testing one of them, apparently led to a short - circuit at the output of +5 V regulator ( IC7 ) caused either by a problem on the card or by an undesired manipulation (the volume pot was left hanging on a wire and may have touched the Mobo)
The short has led to the breakdown of a fuse I added at the on/off switch spot and the LCD screen does not light up anymore .
After removing the defective card , I noticed that the short at the output of the regulator IC7 persists. Thinking that this circuit had been damaged, I changed it but the short circuit remains .
Could one or more integrated circuits on the motherboard be irreversibly damaged ? If so, how can I probe them ? Could the short-circuit have another origin ? (I double-checked solders on the Mobo).

Thanks in advance for all contributions, I must say it’s quite frustrating to step back from a working 3 voice-Ambika to “I don’t know what’s going on”…

Remove all voicecards and socketed ICs. Is the short still there?



I’d recommend changing the regulator.

As I wrote above, I did that already…

Power supply is checked?
I fried one power supply with Ambika, but don’t know how.

Sorry, I don’t know.

@Adrian I also fried one (and it’s probably when the troubles started) and got a second one.

Have you changed only 5V regulator?

Yep. Do you think I should also change the others ?

You have to start debugging from somewhere by dividing MOBO into sectors.
By removing regulators and inserting them you can see in witch line the short is.
It tightens the area where to look for short.
Or maybe 8V regulators are shorting.

I’ll give it a try tonight.

The components that go from the 5v rails to ground are the more likely to cause a short. Other than the regulators themselves. Start at the PSU section with the regulators and capacitors.