Fried Bias Pot?

[Hack_Black]

Ok, now I'm working on a BYOC Germanium Boost. If a trim pot gets fried, does it usually act as a short or open between terminals? The voltage at the trans base is staying the same with bias pot adjustment (it reads full battery voltage - 7.5 volts).

I bought it on Reverb from the guy who built it for cheap. Fixing it is more challenging than I expected.

[Hack_Black]

Does this question make any sense?

[somnif]

Given how a pot is constructed, I'd imagine a damaged/broken one to go open circuit (like blowing a track off a board). I could be wrong though, things can break in odd ways.

Have any pics of the board? Perhaps someone here can spot something.

[Hack_Black]

Maybe I will post a pic, but it is so sloppy. It's ugly too. Guy painted it to be a green mixed with gold color, but I doubt it turned out like he wanted. I don't want it to look like my work, LOL but guess it doesn't matter. Before I got into it the DC jack didn't work and it would cut in and out on battery. It's got torn traces and everything.

[Hack_Black]

Well, here's proof I didn't build it. And I'm not claiming to be a solder jockey either. I'll post circuit pics next.

[Hack_Black]

[Hack_Black]

[Hack_Black]

Why would there be +7.5 volts (that is all the battery power) at the base of the transistor socket?

[somnif]

Ok, first dumb question, is anything shorting out against the back of the pot?

[Hack_Black]

Thanks for the reply. I don't think so. When it was in the box it was. But I've been working on it with just the guitar in/out jacks installed in the box since this adventure started. I'm giving it a break for tonight.

I thought I burned something up by overheating with soldering iron, but it appears that isn't the case.

I have an unused Mad Bean Rangemaster board. But I don't have a non-boardmount pot. I'm not sure what my next approach will be tomorrow. I really need to get a better soldering iron.

[lars]

What transistor came with the pedal? In the pictures, I don't see one.

[Hack_Black]

What transistor came with the pedal? In the pictures, I don't see one.

I took it out while soldering. It's an OC76. The center lug of the volume pot was intermittent. The traces were torn off. I had to scrape the board to expose a trace and solder the lug to it on the component side. I thought I was going to burn stuff up soldering so I took the transistor out.

I'll start working on it again here in a little bit.

[lars]

I did notice there are three purple wires going to the output jack, whereas in the BYOC instructions, it only shows two. It looks like the DC input jack in your pictures is being grounded to the output jack. I would suggest changing it to match how BYOC wired things up in their build document. It can be very easy to mess up the grounding scheme with PNP transistors. Your pedal should be running positive ground.

[jimilee]

What transistor came with the pedal? In the pictures, I don't see one.

I took it out while soldering. It's an OC76. The center lug of the volume pot was intermittent. The traces were torn off. I had to scrape the board to expose a trace and solder the lug to it on the component side. I thought I was going to burn stuff up soldering so I took the transistor out.

I'll start working on it again here in a little bit.

For future reference, you could just run a jumper to the next component in line.

I did notice there are three purple wires going to the output jack, whereas in the BYOC instructions, it only shows two. It looks like the DC input jack in your pictures is being grounded to the output jack. I would suggest changing it to match how BYOC wired things up in their build document. It can be very easy to mess up the grounding scheme with PNP transistors. Your pedal should be running positive ground.

That is weird, the input and output jacks were reversed. the stereo jack should to the input. And that's only if a battery was going to be used.

[Hack_Black]

Thank you for the replies. I chose this forum because some can get so snarky.

I did have to run a jumper instead of trying to use the trace.

Sound is getting through now and the volume and toggle is having an effect, BUT the signal is very weak. The bypass signal is louder.

I'm going to re-check the wiring again. Thanks!