Art Sgx2000

[The musicman]

yesterday when turned on my SGX2000 there was aloud humming noise, i thought maybe the volume was turned up, but it wasn't. Even when i turn down my amp the humming does not go away, and when i mean its a loud humming it really is. I can't even get any sound out of it when i play my guitar, i have took it apart and i can't seem to see anything that is out of place. It looks fine.

So does anyone know what might be causing this problem ?

[Enzo]

Most electronic failures are not visual. Like looking at a guitar to determine if it is in tune.

You have likely lost one of the internal power supply voltages, or the filter cap on one has retired.

If the panel controls and readouts work, then teh computer and its voltages are OK. The analog voltage - most likely +/-12VDC or +/-15VDC - is most suspect. Pick an op amp and see if clean DC is at both rails.

If both rails are low or one is really low, look for a hot chip or a cracked one

If there is a tube, pull it. Hum go or stay?

COuld have a bad op amp - look for DC on an output pin - but that usually doesn't make loud hum.

[Jimbo Bigbelly]

You really need a schematic to troubleshoot this. I tried to get one from Art support but they ignored my request, even though on their support site they said they would supply a pdf schematic. Sigh.
Enzo's probably right. If the front preset select switch is working, it's probably the 12V supply that's died because the DACs which convert the digital signals into the analog output run on 12V. If the preset select doesn't work and the red LEDs don't change, who knows what's failed.

You can check the 3 supply regulators. They are mounted on the heatsink at the rear of the unit. As I recall, the output pin is on the right and the voltage is the last digit(s) of the part number, like 7805 is 5V, the 7812 is 12V. You can set the meter on AC as well to look at the RMS ripple if you've got a good DVM. A hum is probably 60Hz or 120Hz. The analog and digital grounds in this unit are common, so you can use one of the digital chip's ground as reference. Not sure where to find groud pin otherwise.

[Mark Black]

ART SGX2000 Schematic

Since this thread found new life I will post these (ART followed through in my case...)

Enjoy!

[Mark Black]

ART X-15 Schematic

What the heck - since these are usually paired with the SGX2000 might as well toss this in too...

[g1]

Thanks Mark.

Note to Jimbo: This thread is from 2006 .