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So my friend built this amp. We omitted the NORMAL channel from the design and just went with the bright channel since it has an extra gain stage.
We weren't happy with the stock trem/vibrato circuit. It wasn't intense enough. So, we rewired it to a AB763 Twin Reverb circuit and added the LDR.
Twin rev schem: http://www.cnjradio.net/fenderamps/t...b763_schem.gif
6G16 schem: http://elektrotanya.com/PREVIEWS/634...6g16.pdf_1.png
It doesn't work. I've checked and rechecked the circuit.. many times. I wired it to be ON all the time. There's no footswitch jack. I grounded that point as fixed. I left out the 2.2m resistor that connects that point to the bias supply (twin reverb schem). I figure it's only there to turn the circuit OFF when the footswitch isn't on.
I added the coupling cap between the last preamp stage's plate and the 1meg series resistor going to the PI. Then connected that junction (per twin schem) to the top of the intensity pot.
I've checked voltages on the vibrato stages' plates, grids, cathodes, and it's moving all around. I think it is indeed oscillating. However, no audible effect when playing the amp. What I'm not sure of is the coupling cap I added, and the 1meg after the cap. In the Twin this resistor is a 220k not a 1meg. I don't see any reason for this to keep the vibrato from working. I also made the intensity pot 50k, not 250k.
So, can yall advise me on troubleshooting a vibrato/trem circuit?
We weren't happy with the stock trem/vibrato circuit. It wasn't intense enough. So, we rewired it to a AB763 Twin Reverb circuit and added the LDR.
Twin rev schem: http://www.cnjradio.net/fenderamps/t...b763_schem.gif
6G16 schem: http://elektrotanya.com/PREVIEWS/634...6g16.pdf_1.png
It doesn't work. I've checked and rechecked the circuit.. many times. I wired it to be ON all the time. There's no footswitch jack. I grounded that point as fixed. I left out the 2.2m resistor that connects that point to the bias supply (twin reverb schem). I figure it's only there to turn the circuit OFF when the footswitch isn't on.
I added the coupling cap between the last preamp stage's plate and the 1meg series resistor going to the PI. Then connected that junction (per twin schem) to the top of the intensity pot.
I've checked voltages on the vibrato stages' plates, grids, cathodes, and it's moving all around. I think it is indeed oscillating. However, no audible effect when playing the amp. What I'm not sure of is the coupling cap I added, and the 1meg after the cap. In the Twin this resistor is a 220k not a 1meg. I don't see any reason for this to keep the vibrato from working. I also made the intensity pot 50k, not 250k.
So, can yall advise me on troubleshooting a vibrato/trem circuit?
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