Redoing a Pedal

YourGuitarist

YourGuitarist

Active member
Bout to vent...

I've been troubleshooting a pt2399 delay with a big muff tonestack. Custom build.

The blend does not go 100% wet despite it being a pot to pan between dry and wet signal. The pot measures continuity across rotation. There is a volume control directly coupled after.

Then the tone control acts like a volume control which goes to 0 on the treble side. I thought this could've been a shorted cap to GND but alas it is not. Pot measures continuity across range.

Perhaps most confusingly is that while the main delay can be muted via the tone control, I can still hear the repeats.

I've checked the DC voltages which are all fine.

I recycled the pots and some caps from other builds before.

I'm confounded to say the least. I'm wondering is there a point where it's better to start over from scratch?
 
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Found the issue. There was a dual channel dip switch modifying a portion of the wet path and a portion of the dry path. Crosstalk between wet and dry was happening inside the DIP switch.
 
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I'll give the long explanation, excuse me if this is overkill/patronizing.

This is the output stage of the pedal. The eponymously-named-dry signal is being blended with wet signal (Delay Out) before being sent to output jack.

The electrical principle of superposition is how you understand the blend pot. Both the Delay Out and Dry nets are low impedance voltage sources. Each source is seen as an AC gnd by the other. Thus, you have a voltage divider to ground shared by both sources (wet and dry) but in opposite taper.

1784667848099.png
 
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