fullblare Messages: 5 Registered: October 2012 Location: Sioux City
Junior Member
I've been restoring a K250-4 Amp that I purchased locally. Thanks to this this forum I have been able to build a food switch to turn on and off the Fuzz, Selective Boost, Reverb and Tremelo. The only issue I'm having is the selective boost works only for a few seconds when you first turn on the amp and then quits. I have the pedal that came with the amp and have tested it to make sure the potentiometer is good and the cord appears to be good as well. With my electronics knowledge it almost sounds like a bad cap in the RC circuit. Looking at the schematic and "S2" Selective boost cirecuit I'm wondering which cap I should be looking at. Has anyone else run into this issue?
I'm not sure I understand what you are saying. You are using a boost pedal (wah wah) with the amp and the effect stops working after a few seconds? Is this correct?
fullblare Messages: 5 Registered: October 2012 Location: Sioux City
Junior Member
With both the boost pedal and switch board unplugged the selective boost knob on the amp seems to work in each position changing the tone of the guitar. If I plug just the boost pedal in the effect works when rocking back and forth on the pedal for a minute or so and but then has no effect.
If the wah pedal stops working after a short time, I would suggest that you clean the plug and jack connections and check the wah pedal pot. The wah pedal is in series with the ground connection of the boost circuit and the frequency shifts depending upon how much resistance is added in the series circuit. If the circuit works otherwise with the switch, then the pedal pot, wire and connectors would all be the first things to check.
Cool that you have been able to build a footswitch for your amp. There are several of us on this site that are in need of a footswitch like this. Could you post on here the material you used and where you found the parts as well as a diagram of the wiring?