My Microdrive sounds wierd

[SeneX225]

Now, where are we..??
What is working, what isn't and what is partially OK..??

Pedal is still very quiet but everything else is alright now.

[antonis]

What kind of LEDs you're using..??

edit: Let's make some troubleshooting steps:
1. Measure Base voltage (DC) on any point of row D till column 5..
2. Measure Collector voltage (DC) on any point of row C after column 3..
3. Measure LRDs forward voltage drop by putting DMM probes on any point of row D after column 7..
(take another measurement with probes polarity reversed - it should be identical to former one..)

[SeneX225]

What kind of LEDs you're using..??

The usual 5mm reds. To be clear, at the moment of beginning of this thread everything was working fine, with proper volume and all that. Something mysterious happened while I undid Gain pot to measure it.

I have a sneaking suspicion that it might be something to do with wires. The ones I'm using aren't very thick or even good, so I'll try replacing them and get back with the result.

[SeneX225]

As it turned out, I was right for a change. Well, sort of.

I did change the wires for better ones and that made the effect loud again, but then I accidentally unplugged its power and upon plugging it back in, the sound was quiet again, just as before. I think what's going on here is some capacitor is acting up, although I'm not sure how. I'll leave it unplugged from everything to discharge for a couple of hours and get back to tell if that helped.

Upd: It didn't. I understand nothing anymore.

On the other note, I successfully managed to switch out Gain pot to a 100k resistor, and it works as intended. However, there's a side effect: Volume pot stopped working as well. It now stays at full volume however said pot is rotated. I thought it might be Input jack grounding, but moving it from board to volume pot lug that connects to ground made a ground loop. Is there a way to fix this or should I just eliminate Volume pot as well?

[antonis]

I'd make a new build on a brand new board..
(with a socket for BJT placement..)

[ElectricDruid]

As it turned out, I was right for a change. Well, sort of.

I did change the wires for better ones and that made the effect loud again, but then I accidentally unplugged its power and upon plugging it back in, the sound was quiet again, just as before. I think what's going on here is some capacitor is acting up, although I'm not sure how. I'll leave it unplugged from everything to discharge for a couple of hours and get back to tell if that helped.

Upd: It didn't. I understand nothing anymore.

On the other note, I successfully managed to switch out Gain pot to a 100k resistor, and it works as intended. However, there's a side effect: Volume pot stopped working as well. It now stays at full volume however said pot is rotated. I thought it might be Input jack grounding, but moving it from board to volume pot lug that connects to ground made a ground loop. Is there a way to fix this or should I just eliminate Volume pot as well?

This type of "Works! Doesn't work!" sounds like bad soldering connections to me. "Something is intermittent" is more likely for those symptoms than "something is broken". Changing some of the wires or swapping the pot for a resistor means you took away some bad joint and replaced it with a better one, which fixed the issue - rather than it being swapping pot for resistor that actually fixed the issue.
The volume pot going suddenly to max and staying there implies that it's not grounded properly - again, most likely a bad connection.

Make sure all the wires go where they're supposed to, and I'd check all the joints carefully and resolder anything that looks dodgy.

[SeneX225]

This type of "Works! Doesn't work!" sounds like bad soldering connections to me. "Something is intermittent" is more likely for those symptoms than "something is broken". Changing some of the wires or swapping the pot for a resistor means you took away some bad joint and replaced it with a better one, which fixed the issue - rather than it being swapping pot for resistor that actually fixed the issue.
The volume pot going suddenly to max and staying there implies that it's not grounded properly - again, most likely a bad connection.

Make sure all the wires go where they're supposed to, and I'd check all the joints carefully and resolder anything that looks dodgy.

Might as well be bad soldering, because there's an entire Louvre for improvement for me yet. I think I'll follow Antonis' advice and just make a new board (and also get a 100k linear pot and that transistor socket coupled with 2n3904).

Thank you very, very for enduring me!

[SeneX225]

One last thing, I promise!

Since I'm doing a new board anyway, I thought I might as well place mods on it. Can you please check if this is a correct way to replace Gain pot:



An original schematic, just in case:

[antonis]

It's OK..

P.S.
I'd add another row and 2-3 columns to have all resistors horizontal and LEDs/Caps distance more loose..

[SeneX225]

Knowing my tendency to put 400V caps everywhere, this is a very good suggestion, thank you!