debugging breadboarded 9v Electric Mistress

[jdub]

Hello all-

I'm trying to breadboard a 9V Electric Mistress and I'm having some probs.  I'm getting signal through the effect, albeit at a lower level than bypass and with no flange.  This signal is also accompanied by a faint squeal or whine.
I'm following Markus' schematic at gaussmarkov:
http://gaussmarkov.net/layouts/mwelecmiss/mwelecmiss-schem.png. 
No mods or part subs, nor any positive-to-negative ground conversion. 
I've compared my voltages to the ones in this awesome post by sta63bmx: http://www.diystompboxes.com/smfforum/index.php?topic=46519.0
and mine are pretty off.  Details are as follows; all voltages taken in the same manner as above post- DMM neg. probe on pin 8 of 4013, all pots CCW, trims as in post, filter matrix off.

Battery: 9.08V
V+ at breadboard: 9.08V
V- at breadboard: -9.4mV

IC1 (LM324):
P1: 1.02V
P2: 1.02V
P3: 1.02V
P4: 8.88V
P5: 3.8V
P6: 3.9V
P7: 0.6V
P8: 7.4V
P9: 4V
P10: 4V
P11: 2mV
P12: 4.3V
P13: 4.4V
P14: 4.4V

IC2 (4558):
P1: 4.4V
P2: 4.4V
P3: 3.9V
P4: 3.1mV
P5: 4.3V
P6: 4.4V
P7: 4.4V
P8: 8.8V

IC3 (SAD1024):
P1: 0
P2: 13mV
P3: 2.4v
P4: 0
P5: 8.4V
P6: 0.6V
P7: 8.4V
P8: 1.1V
P9: 8.4V
P10: 1.8V
P11: 8.4V
P12: 0.4V
P13: 0
P14: 2.4V
P15: 18mV
P16:0

IC4 (CD4013):
P1: 1.8V
P2: 2.4V
P3: 4.4V
P4: 0
P5: 2.4V
P6 thru P11: 0
P12: 8.8V
P13: 0
P14: 8.8V

IC5 (LM311):
P1: 0
P2: 1.0V
P3: 0.8V
P4: 0
P5: 8.8V
P6: 8.8V
P7: 4.2V
P8: 8.8V

Q1 (2N5087):
C: 0.8V
B: 8.0V
E: 8.6V

As I said, way off.  I've been hunched over this thing for quite a few hours now; I've triple- and quadruple-checked component values and placement.  I'm particularly puzzled by the voltage across pin 2 of the 1024; the bias trim, which should affect this voltage, will only adjust between 0V when ccw and 18mV at full cw.  Voltage across the wiper of this trimpot (when disconnected from 100k resistor) ranges from 0 to about 3.4V.  If I pull the lead from the 100k resistor from it's hole at pin 2 of the 1024, I get this same range across that lead; when I plug it back in (between one lead of the 0.1 uF cap and pin 2 of 1024), the range drops back down into the 0-18mV range across that lead.  In short, I can't increase the voltage across pin 2 with the bias trim.

I hope this info is clear enough.  I'd be grateful for any pointers on where the problem(s) might lie.

Many thanks
jdub

[jdub]

A truly shameless bump

[WLS]

I just posted voltages for a 18v version to this thread http://www.diystompboxes.com/smfforum/index.php?topic=74549.0

I know it's not the same volts as yours, but will give you an idea of how the voltages should be in retrospect to the IC's and their relatioship.

The pedal has not been tested yet but the voltages look good and the template is from GGG's  site.

The only changes to the template was the removal of the 18v transformer and a 1044 charge pump in it's place. The voltages are their so the changes on the template where trouble free.

Bill

[jdub]

Thanks, Bill.  I saw your post and it was helpful, but I'm just trying to figure out why my voltages are all over the map- whether it's a bad chip or what.  I'm seriously hoping it's not the 1024, but I've re-breadboarded this circuit twice with similar results.     My thanks for the reply, though.

[jdub]

OK, so I got this breadboarded EM to work (sort of)- unfortunately, the problem appears to be with the SAD1024, which of course is the suckiest of all problems.  Since I had 2 SAD512s, I wired those up as a sub for the 1024, and I got effect!  It seems, however, that the LFO is not functioning since I am getting no sweep to the sound and the Rate pot has no effect at all.  Manually rotating the Range pot and/or the clock trim does provide sweep.  So, I'm getting there, but I am clueless at troubleshooting LFOs.

Does anyone have any tips for finding where the problem might lie?  I've already zeroed in on the LFO area and checked connections, etc., but I'm not sure exactly what I'm looking for.  I've got the datasheets for both the LM311 and the LM324; I'm assuming I should be getting a voltage swing across pin 7 of the 311, but it ain't happenin'.  Nor am I getting swing on pins 5 & 8 of the 324.  Bad chips, maybe?

I'd very much appreciate any help.  Thanks!

[Thomeeque]

OK, so I got this breadboarded EM to work (sort of)- unfortunately, the problem appears to be with the SAD1024, which of course is the suckiest of all problems.  Since I had 2 SAD512s, I wired those up as a sub for the 1024, and I got effect!  It seems, however, that the LFO is not functioning since I am getting no sweep to the sound and the Rate pot has no effect at all.  Manually rotating the Range pot and/or the clock trim does provide sweep.  So, I'm getting there, but I am clueless at troubleshooting LFOs.

Does anyone have any tips for finding where the problem might lie?  I've already zeroed in on the LFO area and checked connections, etc., but I'm not sure exactly what I'm looking for.  I've got the datasheets for both the LM311 and the LM324; I'm assuming I should be getting a voltage swing across pin 7 of the 311, but it ain't happenin'.  Nor am I getting swing on pins 5 & 8 of the 324.  Bad chips, maybe?

I'd very much appreciate any help.  Thanks!

OK, schematics of LFO are 100% correct, you should definitely get swing at LM324's pin 8 - so you have probably bad chip or you have made some mistake somewhere. It's very simple and common circuit, no catches there.

Btw. CLOCK_TRIM is wired imo wrong on the schematics (to get it's full range, pins 1 and 2 should be connected not 1 and 3), but it has nothing to do with your LFO problem and may not be problem at all (if less value than 25k is needed).

[Sir H C]

I remember fixing one of these that would not LFO, seems that there was something about the startup that would put the circuit into a mode where it wouldn't oscillate.  IIRC I added a large resistor somewhere and it happily worked. 

[jdub]

Tomas, I think you're right about the clock trim- I noticed that, too, so I did jumper pins 1 & 2 rather than 1 & 3.  Thanks!

Sir HC, any ballpark idea where you put that resistor?...

[jdub]

Just a quick update to put this thread to rest: turns out the LFO problem was evidently with the LM324- got a new one, put it in, and I now have a working EM.  Sounds pretty good, too!  Just want to thank everyone for their help. Cheers!