Synthrotek pt2399 dev delay problems

[Luke51411]

I built a synthrotek delay and it works but there is a lot of pop when switched. I built it stock and this popping was present. I then added their suggested mods the feedback 50k pot, the feed blast momentary switch, and the warp delay spst. Pop is present in all the switches and renders the feedblast useless. Also more than half the travel of the feedback pot goes into uncontrollable oscillation that sounds like my amp is going to explode. The warp delay switch works but all it does is make the delay faster at a given setting. I have it wired true bypass to a 3pdt with an led. I removed the led to no affect.
Here are the mods http://www.synthrotek.com/tech/mods/pt2399-dev-board-feedback-mod/
Here are the build instructions http://www.synthrotek.com/kit-assembly-instructions/other/pt2399-dev-delay-assembly-instructions/pt2399-dev-board-bom/

Any help is much appreciated.

[Luke51411]

Any ideas?

[mth5044]

Is there a schematic somewhere? I couldn't seem to find any in the links provided.

For popping, try adding a pulldown resistor - 1M from the effect input to ground (not from the input of the pedal, has to be directly connected to the input of the circuit) or the LED is popping. Both problems are address countless times on this forum, try the search function and I'm sure you'll find something.

[Luke51411]

There doesn't seem to be a schematic. The only thing they provide is the pt2399 data sheet maybe it's just the circuit on that I will check into that when I get a chance. I was thinking the board incorporated a pull down resistor already but on second look I don't think so. I will try adding this and see if it helps. I'm not as concerned with the popping as there are many ways to address that issue. I want to address the other issues I just figured it would be best to describe all symptoms. I have emaile their tech support and haven't heard back yet I'm just getting impatient and want to get this pedal in a workable state. With the feedback pot I tried 25k, 50k, and 100k and all of them have too much of the pots travel going into oscillation I'm just wondering if there is anything I can do to decrease range that goes into oscillation without severely limiting the feedback available.

[slacker]

If it's like most PT2399 based delays the feedback pot is wired as a voltage divider and then has a resistor from its wiper back to the input of the delay. It's this resistor that sets the maximum feedback level, the value of the pot plays very little part.
See if you can find that resistor, making it bigger will decrease the maximum feedback level, making oscillation happen later in the pot's rotation.
Can't really help with the warp issue without knowing what those points they're connecting are.

[Luke51411]

Stupid question. I added the pulldown resistor which fixed the 3pdt pop. What would cause popping from other switches in the circuit? Would I just use a similar method to take care of that?