How to troubleshoot

[Zerro]

Resistor R5 in collector of first transistor 100k - it serves as Gate function. Try play around it, to get at collector of second transisitor cca 5-7 Volts DC. That's my tip.

[Zerro]

Try to sent info what is that machine - type and name, or better, schematics. To help us to consider it. Now I only guess. Generally, as I said, if it is some 2 or more stages transistor fuzz, resistor in collector of first transistor, going from power line, can be too high. Try to set it with trimmer.

[GeorgeFormanGrill]

I'm in the home stretch troubleshooting this pedal. The circuit works, and now I'm running into a few problems loading into the box. Some thoughts on what's going wrong:

1. Pots: Should the bottoms of the pots be connected to ground when I continuity check? I'm worried the way I installed them is shorting the circuit. Any tips on best practices for

2. Circuit: Could the board itself be shorting? I've put a pad of foam underneath the board to make sure it's not coming into contact with the DC jack, LED, enclosure etc. but maybe that's not doing the trick?

Thanks,
George

[Zerro]

Too few of infos about your project. Send schematics, close photos etc... Everything can be mend. Just we cannot only guess.

[Feral Feline]

Pots should be wired up as per the schematic. This isn't a the control cavity of a guitar, you don't solder the backs of pots together here. If anything you cover the backs of pots with non-conductive material to keep them from shorting out the board. Speaking of which...

Yes, you can short the board but it's fairly easy to prevent this with standoffs, some non-conductive material between the board and the enclosure and other components within it.

I use pizza-box "tables" with the legs cut off and hot-glue them to the enclosure if the board is free-floating — but I prefer board-mounted switches and pots to prevent movement/free-floating.


As for crackle... Zvex said "Crackle Ok" therefore it must be so...

[GeorgeFormanGrill]

Got it. Thanks. I realized I wired up the DC jack incorrectly, which was why I wasn't getting any power to the circuit. So, one step down.

Now I have a fresh bug to figure out. I'm getting a signal, but it's very faint. Basically, I have to crank up my amp all the way to eleven to get any sound, and even then it's not that loud.

What could be the issue here? I tested the circuit before wiring up the enclosure and it sounded fine. So, it's got to be an issue with how I wired up the switch/jacks/LED.

I don't have the schematic, but here's the layout:

http://tagboardeffects.blogspot.com/2015/12/lovetone-big-cheese.html

And here are some photos of the enclosure (not pretty, I know).

Thanks for tolerating all the newb questions, everyone.

Thanks,
George

[Zerro]

My questions - I attached schematic of Big Cheese, I found at web. Is it that machine, you are building?

You mentioned, that you had issue with power connector. Did you only connected it at wrong place (and where?), or you changed wires to PCB? It would mean, that both transistors and op amp got reverted polarity. This will damage them for 95%. There is big rotary switch; by my opinion, here is many times problem - wrong wiring.

- So, get off transistors and opamp and measure them with some multimeter, or exchange. This is I would start with.

- Make measure at red points I made in schematic, if it is that schematic you build of course.

- Control that switch

[GeorgeFormanGrill]

Thanks for sending this over. Yes, I think this is roughly the same schematic, although I'm using BC549 transistors.

I made a pretty dumb mistake and hooked the 9V+ lede to the LED and the LED lede to the + tab on the DC jack. Basically, flipped where the 9V+ and LED ledes were supposed to go here (http://tagboardeffects.blogspot.com/2015/12/lovetone-big-cheese.html). I guess that could have fried the transistors and IC?

Thanks for highlighting the places to measure, super helpful. What measurement should I be getting at those points? Am I looking for a 9V reading on the multimeter?

Also, how do I control the switch?

Thanks again,
George

[Zerro]

Hi, I am affraid I don't fully understand what you did with those "lede"s. But never mind. Now you only controll those measure points, what DC voltages will be there (you will find maximally 9V). Switch controll only to verify that all contacts are ok, at the proper pins.

[Feral Feline]

...
I made a pretty dumb mistake and hooked the 9V+ lede to the LED and the LED lede to the + tab on the DC jack. Basically, flipped where the 9V+ and LED ledes were supposed to go here (http://tagboardeffects.blogspot.com/2015/12/lovetone-big-cheese.html). I guess that could have fried the transistors and IC?
...

That won't have fried the transistors & IC. If your trace-cuts are correct all you did was send the power to the IC etc through the CLR, a reduction in voltage is all — what's intentionally done on some pedals and called "Sag" or "Starve" or "Stab" (latter as in stability).

The LED was still getting reduced voltage through the CLR as well, so it didn't pop — LEDs aren't fussy about which side of the equation you limit the juice, but you do have to limit it somewhere along the line. The LED would've popped if you'd fed it a full 9v, though.

Maybe try going through the build beginning to end again; pretend you're starting from scratch and check each component is the correct value as you "place it", and oriented correctly as well. As you go, check for cold solder-joints and re-flow anything suspect.

After that, do the same for each wire while comparing it to the schematic.


It may help to leave it for a few days, re-approach with a "fresh" set of eyes. Numerous times I've done so and saw a mistake that previously while in the moment I kept not-seeing every time I looked over the build.

[mgalicki]

Any idea on this MXR rebuild. using an audio probe, everything to the left of the red line with the exception of the (4) 47nj100's with the purple X on them gives me sound when the phaser button is engaged. Also the (2) lugs on each chip with red circles on them. I do have normal sound from my guitar when the phaser is in off position.
So should there be sound off anything to the right of the red line? Thanks in advance.

[jimilee]

What happened before it stopped working?


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[mgalicki]

I disconnected R26. I was going to put a switch to cut & add it. But now it doesn't work with it connected or not. Geuss I gotta hit all joints to eliminate a cold spot??

[jimilee]

That's a good start, is that an MXR board or where sis it come from?


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[mgalicki]

It's an aftermarket from https://store.generalguitargadgets.com/collections/kits/Phase-Shifters