Duovibe not vibeing

[selfdestroyer]

I was on a roll today with my fail box as I fixed a Cardinal and a SFT that were not working so I grabbed this DuoVibe and its still a no go. Any suggestions would be appreciated.

(1) Project Name
DuoVibe by Effdub

(2) General description of the problem
I get a solid LED for D2 and clean audio passes. No vibe going on.

(3) Steps that you have taken to try to resolve the issue
I replaced the 2N5088's with known good ones. I replaced the 4558 with a known good one that I tested in a Green Bean. I have probed around a bit but can not find a fault. My troubleshooting skills really lack.

(4) List any substitutions you used for parts/values
No subs.

Voltages:
IC1:
1) 8.4v
2) 7.9v
3) 7.8v
4) 8.3v
5) 8.4v
6) 7.8v
7) 7.8v
9.0v

Q1
C 5.7v
B 3.9v
E 3.7v

Q2
C 5.7v
B 3.9v
E 3.6v

Q3
C 9.4v
B 3.6v
E 3.2v





Cody

[midwayfair]

Try a different IC -- just a couple different things, like 1458 or even an 072. If your LED isn't blinking, your problem lies in the oscillator section.

[selfdestroyer]

Try a different IC -- just a couple different things, like 1458 or even an 072. If your LED isn't blinking, your problem lies in the oscillator section.

Thanks Jon, I figured as much and tried a RT4558 and also a JRC4558. I will look for any bridges and try the ICs you suggested and report back.

Cody

[Morgan]

Sorry to bud in, was just perusing duo vibe builds and noticed your voltage readings. Your op amp won't work at those voltages, and what immediately jumps out is the voltage on pin 4. It should be ground / 0 volts. Pin 8 voltage looks fine, and the other pins are probably out of whack because of the lack of a ground reference. I bet the LFO starts turning as soon as you fix the ground connection on that pin.

[Droogie]

SOLVED! I had no continuity between pin 2 of the Depth pot and R18 (the end that sees 9v). One jumper later and voila! I'll have to leave it to someone more knowledgeable than myself to explain it. Broken trace?

Not to hijack, but did you ever get this sorted? I'm having issues similar to yours but my LED won't light up. Voltages on the IC jump wildly except for pins 4 and 8 which are correct. My trannies voltages are the same as posted above. Checked values and reflowed all soldering but no love...