SOLVED kliche polarity protection diode fixed, now it squeals

[kristopher]

A friend handed over a Stewmac Ghost Drive/ Kliche to me to repair. It worked for a few years, then went dead. I replaced the bad wiring (some were burnt at the ends), and cleaned what I could. The builder used glue to hold the wires on the the jacks, along with solder. And the pots were soldered and glued too. It was quite messy, because the glue gun made many gossamer threads. And all the solder points on the pcb look VERY dry. As if the solder used wasn't of good quality.
I determined that the polarity protection diode had quit; because when plugged in, there was no sound and the positive and negative terminals had continuity to each other. I checked the diode, and determined that it had continuity to it's positive and negative ends, so I replaced the diode, because it shouldn't allow current to flow both ways.
But now it Squeals. When it's engaged, it's a loud squeal. Affected by the volume pot. When off, the squeal is faint, and the signal gets through. Also, the LED doesn't lite up, but it's a good one that I installed, cause the old one was burnt. Also also, about 5 capacitors were burnt/melted by the builders soldering gun.
IC voltages are:
tc1044s
1 9.34
2 7.66
3 0
4 5.15
5 4.48
6 7.88
7 7.33
8 9.34

IC2 tl072
1 8.8
2 5.26
3 5.07
4 4.47
5 5.07
6 8.75
7 8.75
8 9.45

IC2 tl072
1 5.07
2 5.07
3 3.98
4 0
5 5.2
6 5.2
7 8.74
8 9.34

Any help is always appreciated.
Photos are up next.

EDIT: A faulty charge pump caused the squeal.
When I got that swapped out, I re-soldered a few more poor spots, and removed some extra solder lumps. The LED had a fried pad, so I jumpered to the closest resistor. And Voila, full Kliché glory. Thank you Robert and Coda. Rock On.

 

[kristopher]

photos

 

[Coda]

Make sure the dual-ganged pot is as insulated as humanly possible. Klon builds are notorious for the dual-ganged pot shorting out against something, resulting in some interesting results...

Edit: StewMac sure doesn't make it easy to find the build docs. I'd expect more from a $125 kit, but then, it IS StewMac...

Edit 2: also, what are the diode being used for clipping. They look like Shottky diodes to me...

 

[kristopher]

Heating the iron now. And I agree. Double U tee eff StewMac? How's anyone gonna know what they're getting into if you don't show them the instructions first. Rude.

 

[Coda]

Heating the iron now. And I agree. Double U tee eff StewMac? How's anyone gonna know what they're getting into if you don't show them the instructions first. Rude.

You can use the docs for the PPCB Kliche, its the exact same pcb...

 

[kristopher]

The dual gang has been removed. And the squeal is still there.

 

[Coda]

Ok, that tells us a bit. There is one cap that looks pretty mangled...the blue one. That could be an issue. Could be fine, though. I would definitely reflow every single solder joint, add new solder if possible...

 

[kristopher]

Cap removed. Still Squealing.

 

[kristopher]

I was planning to reflow all the solder. But I wanted to figure out the issue first, in case I have to remove more components.

 

[Coda]

I was planning to reflow all the solder. But I wanted to figure out the issue first, in case I have to remove more components.

The reflow may fix the problem as well. In my experience, the last thing you try when troubleshooting is often the solution...

 

[kristopher]

Thanks for your help. But now I gotta walk away from the workbench. I'll reflow and let you know.

 

[kristopher]

Reflowed. Still squealing. No LED. And, when I pull IC2, the squeal stops.

 

[Coda]

Reflowed. Still squealing. No LED. And, when I pull IC2, the squeal stops.

Can you sub in another IC?…

 

[Robert]

Looks to me like your charge pump isn't working properly.

IC2 should have around 18V on pin 8 and -9V on pin 4.


Pull both TL072s and then remeasure those voltages. If they come up to the expected voltages you might have a damaged opamp, otherwise I would replace the charge pump. (TC1044)


By the way, the build doc is right there on the bottom of the product page on the Stew Mac website. (No schematic though, so you can just use the Kliche doc for that)

https://www.stewmac.com/globalassets/video-and-ideas/online-resources/pickups-and-electronics/no-need-to-spend-thousands--build-your-own-klon-centaur-replica/12250_12254ghostdrive-4.15.22screen.pdf

 

[kristopher]

YES! Thank you Robert. The Charge pump was faulty.
I started audio probing, and got frustrated, so I stepped away and played some music to calm down.
I swapped the TL072's earlier, but didn't try the Charge pump. I just now swapped it out and the squeal went away.

BUT! The effect isn't happening. No substantial GAIN and not much VOLUME, and no LED. And the new charge pump got VERY hot, so I pulled it.

 

[Coda]

YES! Thank you Robert. The Charge pump was faulty.
I started audio probing, and got frustrated, so I stepped away and played some music to calm down.
I swapped the TL072's earlier, but didn't try the Charge pump. I just now swapped it out and the squeal went away.

BUT! The effect isn't happening. No substantial GAIN and not much VOLUME, and no LED. And the new charge pump got VERY hot, so I pulled it.

Can you measure the voltage at Pin 1 with the charge pump removed?…

 

[kristopher]

Can you measure the voltage at Pin 1 with the charge pump removed?…

Empty charge pump TC1044 socket reads
1 9.35
2 slowly lowering from 4~
3 0
4 slowly lowering from 2~
5 9.35
6 0
7 0
8 7.6

 

[kristopher]

With the original Charge Pump, and empty IC1 and 2 sockets, the voltages at pin 4 and 8 on IC2 are 4: -6.9 and 8: 16.64
IC1
1 4.66
2 4.66
3 4.24
4 0
5 4.66
6 4.62
7 4.44
8 9.34

IC2
1 4.62 then lowers to 4.48
2 4.66
3 4.66
4 -6.9
5 4.66
6 4.62 then lowers to 4.48
7 4.62 then lowers to 4.48
8 16.64

So I smartened up, and popped open my fully functioning Kliche mini, and measured the IC's. IC1 is the same, but IC2 is:
1 4.62 then lowers to 4.48
2 4.62 then lowers to 4.48
3 4.66
4 -9.32
5 4.66
6 4.66
7 4.62 then lowers to 4.48
8 17.97

Also, CODA, yes, those are Schottky diodes in the clipping section. I didn't read your added edit from Monday. There are also a few resistors that aren't uniform. I assumed coming from Stewmac, it would've been a kit. Perhaps the builder got creative?? My friend that owns the pedal and has used it for a few years had no complaints about the effect she was getting out of it, until it quit.

 

[Kidlargo]

YES! Thank you Robert. The Charge pump was faulty.
I started audio probing, and got frustrated, so I stepped away and played some music to calm down.
I swapped the TL072's earlier, but didn't try the Charge pump. I just now swapped it out and the squeal went away.

BUT! The effect isn't happening. No substantial GAIN and not much VOLUME, and no LED. And the new charge pump got VERY hot, so I pulled it.

That's where my squeal was coming from. Stewmac sent me a whole new kit and I swapped pumps. Bingo!! I have more 1044's now so the new pedal is finished. I just have to decide on graphics. These pedals sound real good. I did the 2 Kings a couple weeks ago and it pretty much kicks ass. Now on to something else lol...