Problems with ENSONIQ SQ-1 - No Sound

[bayouland]

I'm also having trouble with my SQ-R. All digital functions seem to work fine, but no sound. It keeps blowing the fuse at F4. When I disconnect the cable from the power board to the main board, the fuse doesn't blow, so the problem isn't in the power board. Anyone have any suggestions? Has anyone ever found a service manual or schematic on this unit?

David

[bayouland]

Nobody?

[Enzo]

Ensoniq "service manuals" are a joke. I used to be one of their authorized service centers. Schematics were not available even to us. Only much later did they sell us a $100 collection of schematics only for out of production models. I don;t recall if they included SQ-R.

If the power supply alone works, then look at how the power is distributed. The main board of course, but the display/control panel is separate I seem to recall. Disconnect what you can to isolate the problem to one board.

What does F4 do? It may blow, but when it does, disconnect the loads and fire up the power supply. With F4 blown, what voltage is missing?

If the computer works, and no sound I would suspect one of the 15v rails is missing. so explore what on the offending board could be shorting that supply out.

[bayouland]

Thanks Enzo. I just disconnected each board one at a time and the fuse still blows. That tells me that it's the main board. I'll start exploring the 15v power rails tomorrow.

David

[bayouland]

Hey Enzo, I found it! It was a bad diode. I ordered a new one which should be here in a few days. I'll let you know how it works out. Thanks for your suggestions.

David

[bayouland]

The diode was the problem. Replaced it and I'm up and running again! Thanks Enzo for your help.

David

[yu-go]

mine was like that:

No sound, no midi in/out
No output in Q21 7915
I found C98 capacitor measuring 0 ohm.

Replace new one. Now works fine

[Mikeyd]

I know this is an ancient thread, but I just fixed my SQ-1 Plus no sound issue by replacing the volume pot. It also has a bad battery that I replaced. For some reason the first three and last three keys do not work. One key to the left also not working. I disassembled the keyboard and cleaned everything and checked the solder joints. More to come.

[joebugs]

Hello All! My SQ-1 suddenly developed screeching noise from outputs and headphones. Swapped with a supposedly working power supply from Syntaur, powered up silent, Piano sound #1 came on, followed by it plus its reverb, then seconds later the screeching. Re-installed original supply, then same effect resulted. Clean and working for 5 secondss, then noise. Any thoughts? Thanks!