Help with Effects Layouts Break Action Debugging

[ElectricDruid]

Nope, it was in correctly (at least according to the printing on the board), and the socket was also the right way around. In another interesting development, I finally got a new TL074 in yesterday, plopped it in and.....nothing.

Aww, how disappointing! Oh well, onwards, ever onwards...

I haven't checked voltages yet, but suspect they would probably be the same. Could I have a solder bridge somewhere around the socket or something?

Worth checking the voltages just to be sure. And since we've now eliminated a faulty chip as the source of the problem, we know that it must be on the PCB. We also know that it's not on the part of the PCB that deals with Vref, so that narrows it down.

Have a look at that C1 that I mentioned earlier. But yeah, you're probably looking for a short of some sort (some other bad component is the only other possibility, realistically, but a short is more likely).

[ddavis20341]

Appreciate the continued help! I will double check those voltages, check out C1, and maybe get another set of eyes to look over the board for shorts - it's probably something really small that I'm just missing somewhere.

Still pinching myself a little bit that ElectricDruid is helping me debug a project 

[Sasan]

I'm also having troubles with this PCB. I've built two of those and both have the same problem:
The TS side sometimes (when I play faster on higher frets) sounds like a fuzz with a dying battery or gated fuzz. When I disengage the TS side and turn it in again, it sounds normal until playing faster again...the voltage is jumping af.

I really really thought it's only my fault and disability to properly solder that this sounds as it sounds...but I checked all solder joints, changed ICs & transistors, but having a second one built that behaves almost the same (it sounds great until you really start shredding, then the TS side starts to get fuzzy) makes me think that (besides my soldering capabilities) something in the schematics of this pcb is not thought out well...

[ddavis20341]

Yeah, it sounds very possible there could be something going on under the hood with the voltages on that (or maybe something like a leaky/faulty cap? I had a similar problem with a Hudson Broadcast build once, and suspect I probably didn't sufficiently spec out the caps to be able to handle the higher voltages for the circuit).

Strange that it happened on two, but could also point to something consistent in the parts, like a resistor value that is off in both or a leaky/faulty cap, rather than workmanship things like a solder bridge or cold joint.

I finally have some time to dive back into this again. I just checked the voltages again, and they're all the same as the first time (slightly higher across the board because of the power supply I was using, which measured at 9.7v).

Pin 1 - 8.8v.    Pin 14 - 8.7v
Pin 2 - 0.42v.  Pin 13 - 8.7v
Pin 3 - 8.03v.  Pin 12 - 8.72v
Pin 4 - 9.45v.  Pin 11 - 0v
Pin 5 - 4.01v.  Pin 10 - 4.01v
Pin 6  - 8.05v. Pin 9 - 8.05v
Pin 7 - 8.05v.  Pin 8 - 8.05v

Also pulled the IC and did a voltage reading. Pins 6 - 9, and 11 and 13/14, would start off at higher values and then gradually bleed down to 0 (over the span of 20/30 seconds or so - don't know if that info is helpful).

(no TL074, socket empty)
Pin 1 - 4.4v    Pin 14- drop
Pin 2 - 0.3v.   Pin 13 - drop
Pin 3 - 4.5v.   Pin 12 - 4.45v
Pin 4 - 9.5v.   Pin 11 - drop
Pin 5 - 2.25v. Pin 10 - 2.25v
Pin 6 - drop.   pin 9 - drop
pin 7 - drop.   pin 8 - drop

Did a pretty thorough check for errant strands, replaced c1 (and c2, just for fun), and reflowed a bunch more stuff, but still no dice. The signal still stops around the same point as well.

I'll keep looking for shorts, but any other words of wisdom?