I’m glad you have confidence in your meter. Do you have as much confidence in your meter as in your ability to read it correctly (if it’s one of those analog meters)? I know for me those analog meters can be confusing.
I was referring to the relay continuity tests…when I was asking about power on or off, not voltage tests. Please let me know about this.
The voltage on R28 is of no consequence because C17 is removed.
The voltage on pin 5 of U2 is not off enough to keep signal from passing through that opamp.
If the optocoupler’s LEDs are not lighting up, then that would cause no signal to pass through the pedal when the bypass LED is on (when the effect is engaged). It would be unlikely that both optocoupler LEDs are not working, so are you sure this is happening? Either way, as I said earlier, you have more than one issue going on here because you are still not getting signal through the pedal when the bypass LED is off (the effect is bypassed). This is a much bigger issue than the previous one. The signal path is very simple in the bypass circuit….from the input jack tip, through the relay, to the output jack tip. If you are getting signal into the pedal and it really is not passing through to the output jack (when the effect is bypassed) then it can only be 1 (or 2) of 2 things: either there is a bad or broken connection somewhere (most likely a bad solder joint) or the relay isn’t working correctly. In conjunction with your meter testing this circuit, also please actually try it out with a real guitar signal (it’s important to try it both ways).
This problem (of the pedal not bypassing any signal) suddenly started when you re-flowed the solder joints and removed C17, correct? So it stands to reason that something you did in that process is causing this. Check all those connections that you touched up with the soldering iron. Make sure the input and output jacks are soldered correctly (re-flow them). Make sure the remaining pads (and traces) of C17 are not shorted to ground (see if the output jack tip is connected to ground…continuity test this). Is the relay really switching? You can test this with your continuity tester by following this image:
https://zeppelindesignlabs.com/wp-content/uploads/2023/06/relay-jpg.webp
The red lines represent the continuity you should have when the effect is engaged, and the blue lines represent the continuity you should have in bypass. Make sure you are testing the correct pins. This picture is taken from the top of the board, but it’s symmetrical so the bottom of the board is the same.
Please take the time to go through (and do) EACH of these things I’ve listed here in this post, until you find the problem. Let me know what you find.
-Brach
