Cave Dweller Dub Edition, distorted output

[marmora]

Hi friends,

Having some trouble with my Cave Dweller Dub. Heavily distorted output, volume is much louder than clean signal.

http://madbeanpedals.com/projects/CaveDweller/CaveDweller.pdf

Modifications: 680k for R1, 560k for R12, socket for R20 (though leaving it out or putting 180k didn't fix the problem), R19 uses a couple resistors in series and doesn't quite add up to 620R, but it is close. I am using the MIX mod.

Voltages:

DC jack: 9.19 V

REG output: 5.06 V

Q1
C: 29.5 mV
B: .590 V
E: 2.528 V

Q2
C: 28.8 mV
B: .589 V
E: 2.521 V

IC1
1: 5.06
2: 2.52
3: 1.5 mV
4: 1.3 mV
5: 2.908
6: 2.528
7: .940
8: .947
9: 2.528
10: 2.527
11: 2.527
12: 2.529
13: 2.526
14: 2.524
15: 2.626
16: 2.529

IC2
1: 5.06
2: 2.527
3: 2.3 mV
4: 2.3 mV
5: 2.94
6: 2.521
7: .863
8: .830
9: 2.521
10: 2.528
11: 2.528
12: 2.520
13: 2.528
14: 2.529
15: 2.698
16: 2.529

I know it's a small amount on pins 3 & 4 of each IC, but I'm thinking there should be no voltage there.
I can post photos of my build if needed. Thanks a ton!

[selfdestroyer]

You may need to post some photos but I will take a stab.

Have you tried multiple PT2399's? They are known to be flaky unfortunately.

also, If you look at the schematic and you take an audio probe I would start at pin 16 of the PT2399's and see if you get clean signal before the PTs. Next check the output on pins 13 & 14 and see if there is distortion there.

Hope this gets you pointed in the right direction.

Cody

[flanagan0718]

Did you ever get this going? Pictures would be good if you are able to post them.

[marmora]

Thanks for the replies guys. Finally got around to testing this out a little more.

I've tried multiple PT2399 chips and they are all pretty similar. If I turn down the volume on my guitar about 3/4 of the way, I can have fun with this thing, so I'm wondering if I didn't just botch a resistor value somewhere.

Tested with the probe and I am getting distortion at pins 16, 13 and 14.

I'll double check the pictures and hope the laptop screen magnifies any goofs

[madbean]

Why kind of guitar/pickups are you using to test?

[flanagan0718]

Let me know if you need any 1/8 resistors. I should have what you need.


Sent from my iPhone using Tapatalk

[marmora]

Why kind of guitar/pickups are you using to test?

Passive humbuckers, though not super hot/high outputs. Tried a couple different guitars as well and the story is the same. Have been plugging directly into the pedal (first in chain).

[madbean]

Why kind of guitar/pickups are you using to test?

Passive humbuckers, though not super hot/high outputs. Tried a couple different guitars as well and the story is the same. Have been plugging directly into the pedal (first in chain).

Okay, thanks. First thing I though was an impedance issue due to the volume knob thing. Could be that the input resistor needs to be lowered further. I'll look at your pics a bit more and see if I have any suggestions.

[marmora]

Got it going today! Thanks for everyone's encouragement.
I had tried raising the value of R1 to 1M and that actually made things worse. So I went back to 680k, retouched a couple spots where I thought whiskers could be touching and got it going.
Will post a build thread ASAP.