Peavey VK100 with dead switching system

[ken]

I just picked up a Peavey ValveKing 100 with a dead channel switching system - The +14vdc power supply is shorted out.

The problem is that there are LOTS of numbered jumpers on the circuit boards, but none of these actually appear on the schematics. Would anyone know which board jumpers are for what functions on this amp?

PS. I already called Peavey, and they couldn't help.

Thank you,
ken

[Jazz P Bass]

Exactly which jumpers are you refering to?
I am not sure about the VK100, but a lot of printed circuit boards will have jumper wires on the board to connect different parts of the circuit.
Usually this type of board is single sided, where the copper traces are on one side.
When laying out a board sometimes you cannot get from here to there.
So you add a top layer "jumper".
It doesn't have anything to do with anything else.

[CharlieP]

Here is the schematic!

[Jazz P Bass]

Peavey VK100 power supply

If the +14Vdc supply is dead, check the fuse.
F203 3amp Time Delay.
If this fuse is indeed open, you also do not have heater voltage.

[ken]

The VK100 has about 30 different jumpers scattered all over the PCB board. Cutting a jumper is good for troubleshooting multiple problems in an amp, as it allows you to quickly isolate the different fault areas for repair. Just replace the jumper when you do the bad parts.

This VK100 had good heater volts, but read short at the 400ohm 5 watt resistor fed by the heater line. In the end, I found both the relay diodes D103/D104 were shorted out. Since these were 1N4148's, they didn't pass enough power when shorted to overheat anything else.

Thank you, Ken

[pecorporation]

Did you test D103/D104 in circuit? They will read shorted in circuit because they parallel the relay coils. Do the channels when using the remote footswitch? If yes, then I'd first look at the footswitch jack. It may have a bad solder joint or failed shorting contacts.