Um... nearly every point in my circuit reads 4.86v. What?

[kvandekrol]

Building a Deadringer... I had a crazy problem with this a little over a week ago. Since then, I etched another board and transferred most of the parts over to the new PCB, leaving out the caps, transistors and diode in the power section. Things are better - nothing is burning this time! - but I am again having a very strange issue and needing guidance on how to troubleshoot: with the exception of the few points which are connected directly to +9v, and of course the ground connections, every single component I measured came out to between 4.8 and 4.9v. I mean... I tested a number of resistors, a few caps, all the legs of the IC, Q1, Q2, and every offboard connection along the top (pots and switches). EVERY SINGLE ONE was right around 4.86v!

Pedal behavior: it passes signal through, but largely unchanged from the input. The volume works (though the max volume is equivalent to approximately unity gain), the tone barely works, the gain does not seem to have any effect. The switches make a very slight difference but not very much. I audio-probed, and nearly every point I tested gave the same sound, with only slight variations... a couple of tiny changes in volume and treble here and there, but really very little.

And after I leave it on for about 5-10 minutes, it starts this horrible crackling. When I did some readings while the crackling was happening, Vb shot up to 6 or 6.5v, wavering pretty unsteadily. This voltage rose to an average of about 8.5v over the course of a few minutes before I shut it off. The crackling was intermittent and would stop sometimes, at which time Vb dropped back in the normal range, but it would start up again soon after.

The only changes to report are that I don't have any LEDs in place yet, and I jumpered pads 1 and 2 of the boost switch since I am still waiting on a second stomp switch.

Additional notes: Before I noticed that everything was measuring at Vb, and before the crackling started, I replaced C5, C8 and C9, thinking something was the matter with the drive portion of the circuit, since that was the control that didn't work... no change.

[PRR]

Most of the circuit will sit at 4.5V normally.

Read the transistors. Should be 4.2V and 3.6V.

Crackle suggests bad joints.