White Horse not working

[Loxodonta]

Hello all.

I've built a white horse, and it is not working. The bypass board seems to be working properly, and is outputting the correct + and - voltages, but when I turn the effect on the whole signal cuts out. If I crank all of the knobs I do get a very quiet distorted signal coming through, but that's it. 

I have a version 4.2 board, and am using the version 5 clipping, with the 1N914 diodes stacked. I was worried I might overheat one of those when soldering them together, could that cause problems with the whole circuit?

Going through and testing the voltages, I seem to have mV readings in a few places where I'm not supposed to have any, and the voltages to the clipping diodes are wildly different from whats shown in the build doc.  I also soldered in the big chip in the TLE 2074, would overheating it cause these problems?

All voltage readings were taken with the LED in place, pre-gain cranked, and all other knobs all the way down.

Any help is much appreciated.

Also idk  why the photo got all stretched like that but hopefully y'all can see things well enough.

[Aentons]

I can't tell from the pic but (I think) if you are using regular diodes rather than the bs170 you need to jump the middle pin hole over to the other that goes to ground . I believe the bs170 does that internally as part of the body diode.

[Loxodonta]

I can't tell from the pic but (I think) if you are using regular diodes rather than the bs170 you need to jump the middle pin hole over to the other that goes to ground . I believe the bs170 does that internally as part of the body diode.

Yep, the middle holes are empty, still reading voltage on those empty pads though.

[Loxodonta]

Another question. Going through everything trying to double check stuff, including the switching board. Everything works fine in bypass mode, and the relay clicks when I use the switch, lighting the led. When the effect is bypassed, the "IN" pad is grounded as stated in the build doc. However, the "OUT" pad is grounded in either state. Is this supposed to be like that? I'm examining my soldering for shorts and whatnot but I'm not seeing any.

[Loxodonta]

Update: Disconnected the White Horse output from the switching board. The out pad on the switching board is no longer grounded, but the output from the effect is going to ground somewhere. I can't find any obvious shorts on the white horse board, could a bad component cause this?

[Loxodonta]

New update:

I realized that the out pad on the effect board was grounded because the level pot was turned all the way down.  I then desoldered the pots, double checked all the solder joints underneath them, and reattached them temporarily on leads. If I crank every setting, I get a slightly compressed signal that's roughly the same volume as no effect.  The bass setting is the only one that seems to work as expected, every other control seems to just mute the signal if backed off.

HOWEVER, If I decrease the pre-gain trimmer, it does this crazy oscillating stuff when you move the other controls.  You can hear it in the video linked below.  My best (uneducated) guess is that I fried the TLE2074 when I soldered it in. I know I should have used a socket but I forgot to order them and didn't want to wait, haste makes waste I suppose.  I ordered another from Mouser (and some sockets this time), but if anyone can confirm my suspicions are at least logical before I go through the trouble of desoldering it, I would be very grateful.

https://i.imgur.com/pmQcm7z.mp4

[jimilee]

You should audio probe it before you go chasing down dead ends. Wouldn't want you to have to replace things unnecessary.


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[Loxodonta]

You should audio probe it before you go chasing down dead ends. Wouldn't want you to have to replace things unnecessary.


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YES! I've never used an audio probe and I was a little intimidated by trying to read the schematic and follow it on the board, but I found the problem pretty much immediately.

The .22u cap at C12 was dead for some reason. Appearance wise it looked fine, but it wasn't passing any signal. Replaced that and now the circuit works as expected.

Thanks for your help!