Another request for assistance - this time a Green Rhino

[Kalimna]

Greetings Folks,
I'm afraid I am after a little more assistance in debugging a pedal. This time it is the Way Huge Green Rhino from this blog, http://tagboardeffects.blogspot.co.uk/2016/05/way-huge-green-rhino-mk-ii.html
The issue is a loud high pitched whine and stuttery distortion that develops after 20 or so seconds of the effect being engaged. Initially the sound is rather nice indeed, but it seems to develop the whine when the controls are adjusted, especially the 'curve' control. In fact the whine stops if the curve is at zero, but there is still a negative effect on the tonal quality (sorry can't explain it better than that).
I have triple checked component values (including the pulldown resistor which I had at 10k, now corrected) and placement, as well as the cuts and links. As far as I can tell, there are no errors there. I have also knifed the tracks, so I don't think there are any solder bridges.
Here is a list of the pin voltages, which seemed rather invariate as there was almost no difference in readings whichever position the controls where in. It also struck me as odd the similarity between several of the IC pins - though I fully accept my own knowledge is more likely at fault here. Supply voltage was 8.94V from my PSU

Transistors Q1-Q4 all reading the same :
E- 4.08v
B- 4.38v
C- 8.94v

Transistor Q5
E- 4.64v
B- 5.26v
C- 8.94v

LM833 (pins numbered 1 at top left, running anti-clockwise)
1 - 5.28v
2 - 5.27v
3 - 4.98v
4 - 1.1mv (inc to 1.4mv with control at max)
5 - 5.26v
6 - 5.27v
7 - 5.28v
8 - 8.94v

LF347
1 - 5.28v
2 - 5.28v
3 - 5.28v
4 - 8.94v
5 - 5.28v (dec to 5.24v with control on max)
6 - 5.28v (dec to 5.24v)
7 - 5.28v (dec to 5.24v)
8 - 5.28v (dec to 5.20v)
9 - 5.28v (dec to 5.24v)
10 - 5.29v (dec to 5.24v)
11 - 1.1mv (dec to 0.9mv)
12 - 5.29v (dec to 5.19v)
13 - 5.29v (dec to 5.21v)
14 - 5.29v (dec to 5.21v)

Nothing appears to be getting hot if left on for 10-20mins.
My thoughts are
1 - incorrect component placement/value or solder bridge
2 - faulty (or damaged) IC or transistor (most of the 2n2484's measured about 450-500 hfe, but one was about 200)
3 - as the pedal works initially, maybe a capacitor related issue

I do have spare IC's, so I will check those. I do not have any more of the 2n2484 transistors, but have plenty of other NPNs - what would be a suitable replacement?

Again, any thoughts/help is greatly appreciated, before I populate a new board.

Cheers,
Adam

[Travis]

Seems like there is some problem with grounding in your build. Pin 4 of the LM833 should be grounded so you should see 0V there. Pin 11 of of the LF347 should be grounded and 0V as well. Transistor voltages seem to indicate an issue with grounding as well

[Kalimna]

Travis - thanks for the reply. I'll check over the ground wiring again. I suppose it's a daft to question to ask where the problem is likely to be? When you say there looks to be an issue with the transistor voltages too, approximately what should they be?
Cheers,
Adam

[Travis]

I don't know. Seems like nothing is grounded on the board so I'd be looking for a missing/misplaced wire, cut, or link

Not sure what the transistor voltages would be, but I'd expect the emitter voltages to be lower than that

[Kalimna]

A brief update..
Thanks again, Travis, for your help. I had another look over the ground wiring, and there was definitely continuity (with perhaps half an ohm resistance measured) between the power socket -ve and the ground pins of the two IC's. So I swapped out the chips, and the pedal seemed to work, but was very dependent on having the board flexed in a certain way - which I expect suggests a short somewhere?
Rather than make the soldering even worse than it was (I'm getting to grips with soldering, but my de-soldering would only leave greater likelihood of bridges), I decided to build a fresh board.

So, managed to get it all back into the original enclosure, and no sound at all when engaged. A quick check over and I found a missing link. And wouldnt you know it, there was an IC socket overlaying it. So a little jigging around, and hey presto, a working Green Rhino Mk2. Phew.

Time to fire up the Red Llama too.
Cheers,
Adam

[Travis]

Are you still getting a voltage other than 0V on those pins that I mentioned before?

Sounds like you need to run something between the strips to clear out bridges. It can be a knife, thin file, whatever. I use the corner of a little metal ruler because it doesn't cut deep into the board and it's a good width

You can do a continuity test to find shorts

[Kalimna]

Prior to discovering the missing link (underneath the LM833), I had checked the pin voltages and the buffer transistors all had good supply voltages, but almost nothing at emitter or base. Both chips read 0V on the appropriate pins, but less than 1V on the remainder (LF347 had good supply voltage).

Once the link was inserted, the pedal seemed to work fine so I havent run the DMM over it again. Perhaps I should, for completeness sake.

The above applies to the second build, I abandoned the first as I had tried the suggestions with nothing obvious turning up (short of replacing the original chips, which certainly helped). I had knifed the gap inbetween tracks with a stanley knife, and I suspect this made any shorting worse due to new slivers of copper being created! However, I shall try your suggestion of a steel rule next time - much less likely to damage the copper.

I did do a continuity test along the ground path (to the IC's at least), but found only a minimal resistance (about 0.5 ohm) between the jack socket and the IC.

Cheers,
Adam