SOLVED Did I destroy my Sonomatic?

[giovanni]

I was so excited on Sunday to finish my Sonomatic build. I had just switches and jacks to solder so I did. Then in the evening I decided to test the pedal. It did not go well. The effect worked for the most part but the bypass with tail was not working or working intermittently and the effect was also intermittent at times. The tail switch seemed to be faulty, I realized I had to push against its side to make it work. I started poking around the guts to see if I had shorts. At some point I accidentally touched both + and - pins on the power plug with my handy screwdriver and I saw a little spark. After that, quiet. True bypass works (so the foot switch works) but nothing else did. I was pretty bummed and I don’t know if I’m gonna be able to fix it by the time I leave to Italy (I was gonna gift it to a friend over there).





I haven’t started troubleshooting yet. I guess I’ll start by checking the power circuit and see if I fried any of the voltage regulators. Next I’ll have to desolder the faulty switch for the tail mode. Finally I had replaced the J113 with a J112 (or viceversa I can’t remember) so I wonder if that may also be messing with the tail mode.

I’m so very bummed by this. Hopefully I can get it back in shape.

 

[giovanni]

Ok finally had a few minutes to start debugging. Here’s what I found so far:
* the dpdt switch for true bypass doesn’t work in the down position: only one of the poles connect; if I gently push the lever sideways it makes a connection; so that’s gotta be replaced
* the bypass switch may have some short but I am not sure since it could be a weird interaction with the TBP one; I’ll replace it after replacing the first switch it has issues;
* the mishap with the probe I had the first time I poked around seemed to have caused no damage, the diode is fine and so are the regulators;
* I get effected signal on pin 7 of the 2134, but no signal on pin 1, which may be consistent with the broken switch at the top.

I’ll do some surgery and report back. Wish me luck!

 

[darwin999]

Good luck, I hope your power supply also survived.

 

[giovanni]

Good luck, I hope your power supply also survived.

It did actually! I lucked out!

 

[giovanni]

Ok I replaced the DPDT switch for the trail mode. I’m getting dry signal on pin 1 of the OPA2134 and effected signal on pin 7. I am having a really hard time understanding what the switch nomenclature is on the schematic, it makes no sense to me. If anybody has cracked it I’d appreciate the help. But based on common sense my next guess is that the main 3PDT bypass switch may also be busted or maybe I have a short. I’ll check continuity first and maybe try to replace it.

 

[giovanni]

Alright, last night I finally did some more debugging with the audio probe. I desoldered both foot switches and manually tested the on/off positions for both, which worked. I then replaced the 3PDT because one of the poles was shorting out in both positions. And that was it. The pedal finally works as expected! This was a beast of troubleshooting (two faulty switches!) but I’m glad I got it to work.

The 2399s I used are pretty noisy but I won’t have time to test a few more before leaving for my vacation: I’m taking this guy with me to gift to a friend. Besides a bit of a high noise floor, this pedal sounds amazing!