Washburn VGA30 Humming

[dpm309]

Have a Washburn South Side VGA30 with a loud humming problem. Cleaned jacks and pots and getting a loud humming with nothing plugged in and all controls at 0. It seems to be coming from the PT. Getting sound and normal volume with a guitar plugged in. I have not worked on many solid state amps and am wondering where to begin?

[shooter]

begin with a schematic


PS, whether tube or SS does basically the same thing, clean, regulated DC to the amp
knowing what the DC values compared to good, as designed, makes life easy.

[dpm309]

Have not been able to find a schematic for this or any Washburn amp. I'll start poking around and get some voltage readings in the power supply.

[PRR]

> schematic for this or any Washburn amp.

The SX30 is online: https://elektrotanya.com/washburn_sx12_guitar_amp_sch.pdf/download.html

This is a very basic chip-amp. Simple power supply. I do not know what a "VGA" is, but if similar +/- some frills, the SX12 plan will give a start.

Note that the main power supply is same-as most tube amps, just a fraction of the volts. If you understand how AC volts relate to DC volts, you can figure if the main cap is working or punked-out.

[dpm309]

Thanks for the schematic. This gives me a starting point to determine where the excessive hum is coming from.