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!
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
Did you ever get this going? Pictures would be good if you are able to post them.
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
Why kind of guitar/pickups are you using to test?
Let me know if you need any 1/8 resistors. I should have what you need.
Sent from my iPhone using Tapatalk
Quote from: madbean on October 04, 2014, 10:41:15 PM
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).
Quote from: marmora on October 04, 2014, 11:18:43 PM
Quote from: madbean on October 04, 2014, 10:41:15 PM
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.
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.