[pmjennings]

One more thing. I tried reinstalling C17, but then the original symptoms that I first posted about reappeared. However, without C17, it operated just fine, so I just removed it again. Something in that circuit is still causing an issue, but only when the circuit is wired in. I think I know what the silencing circuit is supposed to do, but it doesn’t seem vital to my needs. I’ll happily live without it. I put it all back together, and the tremolo sounds great.
Thanks again,
Peter

[pmjennings]

Bingo! There was no 5v at R7, so I ran a short jumper from VR5. I now have rich, deep harmonic tremolo once again. I can’t wait to put it all back together and start using it again. Thank you so, so much for helping me fix this, Brach. If I’m ever in Chicago, I’ll buy you a beer.

Peter

[pmjennings]

Progress! I went through all your suggestions, and they were helpful. The results of the relay continuity test were just as the diagram showed. So, I checked the traces. The trace from the output jack to the relay goes through one of the pads of C17! When I pulled C17, both pads came off with it, so that broke the connection. After running a jumper wire from the output tip to the relay, the pedal again bypasses sound normally. However, as there is still no output in tremolo mode, I’m back to where I started.

I think the problem has to be the lack of voltage getting to the optocouplers. I tried to map the traces to see where those 5 volts @ R7/R8 originate from, but it’s too hard to see the traces with a populated board. Is there a diagram available that maps those traces? My board is version 8.3. I think this could make troubleshooting this issue easier. Or, can I just run a jumper wire from any 5v source to R7? I was going to try this anyway as a test, but I wanted to touch base with you first.

Thanks so much for your patience,

Peter

[pmjennings]

All the voltage tests are done with power on. The meter is trustworthy. It’s just a no-frills unit without the continuity test function. Any inconsistencies are more likely caused by me. I’ve checked everywhere for shorts but all the solder joints are fine. Nothing is touching anything it shouldn’t. I’ve checked all the voltages again and here’s where it currently stands. Pin 5 of U2 is 2.4v. R28 is .45v. With bypass LED on, both optocoupler LEDs read 0v on the square pads. R7 and R8 also read 0 volts. I cut holes to check and there is no light. So, there is no voltage passing through that circuit. All other voltages read as the diagram in the troubleshooting guide illustrates. Do you think U1 is not working properly? There is zero output when hooked up to guitar and amp wether in bypass or normal. I hope you have a clue, because I’m stumped.
Thanks,
Peter

[pmjennings]

Sorry, Brach. I didn’t clarify that in my post from a couple days ago. When I tested the pedal after removing C17, it no longer produced any sound at all. The symptoms that I described in my first post have totally changed. There is zero output from the pedal now in either bypass or normal mode. That explains the lack of tip to tip continuity in bypass. That also makes me assume the relay is the problem. But if that’s the case, do you think it was also causing the original issue?
Thanks,
Peter

BTW, my good meter is broken, so I’m testing for continuity with my cheap old Radio Shack meter that doesn’t have a dedicated continuity test setting. So, I’m testing using the lowest Ohm setting. I need to get a new meter…

[pmjennings]

Brach,
BTW, I’m in S. Korea right now, so I’m typing this while it’s late at night (or early in the morning) there in Chicago. Regardless, thanks for your prompt replies.
Peter

[pmjennings]

Going through step 5 of the TG: There is NO continuity between input/output tips with bypass led OFF. With led ON, there is continuity between input tip and R1. There is NO continuity between output tip and vol. pot center lug. The relay clicks whenever bypass switch is pressed. R28 reads .45v. Everything is installed correctly and solder joints all look good. The pedal worked well for many months until this recent issue. It was never dropped or handled roughly. I’m just assuming it’s a component failure, but finding which one is certainly a challenge!
I hope this info helps.
Thanks again

[pmjennings]

Or, wait. With C17 pulled, isn’t the circuit with Q3 totally removed from the loop? So, in that case, could it be a problem with the relay? I’m just shooting in the dark.

[pmjennings]

So, I finally got back to this. I checked the ISP correctly this time, and there are no shorts between the pins. I pulled C17 and checked that again and there isn’t a short there either. With C17 pulled (and the pads with it #%&@!), the pedal has no output at all. I checked all the cable connections and made sure the volume pot was turned up, but there’s no sound. Voltages still read like before, with .45v on R28. I can read a schematic only basically. I know what all the components are and what they are there to do, but I don’t fully grasp how they all interact together. So, my uneducated belief is that the low voltage on R28 could mean that there is a problem with Q3. It might have an internal short, or something. Could this be true? Would you recommend replacing Q3? I cannot find any problems anywhere else in the silencing circuit.
Anyway, I really do appreciate all your help so far.
Thanks,
Peter

[pmjennings]

Brach,
R29 reads 5v on one end and 2.5v on the other. There is no continuity across C18. I pulled C17 like you said, and there is continuity across those points. Also, on the ISP, I’m reading continuity across all of those pins, but I’m not sure if I’m testing them the correct way. Should I just be testing all of those pins for continuity to ground? If that’s the case, then no, there are no shorts to ground on the ISP. Do you think that Q3 (J176) is damaged?
Thanks for your help with this.
Peter

[pmjennings]

Thanks for the tips, Brach. I reflowed all the connections as you recommended. Still, no luck. I also checked all the voltages, and there were two weird readings. I’m only getting .42v at R28, and pin 5 of U2 is only reading 2.4v. Every other reading was normal. BTW, this isn’t the first issue I’ve had. In tracking down a previous issue, I very well could have overheated a component or two. I like to think I can solder decently, but I haven’t worked with printed boards much until this project. IMHO, the design of the pedal and the quality of the components is excellent. I loved the pedal when I had it working, but I’m starting to feel like my board is a lost cause because of all the abuse I’ve put it through. If I can’t track down the issue, would it be possible to get a fresh board and set of caps, resistors, etc.?
Thanks again,
Peter

[pmjennings]

By the way. Every other function of the pedal still works fine. The volume control is the only issue.
Thanks

[pmjennings]

Brach,
Do you have a gun? Shoot me! Please, shoot me! I went through my board again checking everything and noticed some resistors that didn’t look right. It turns out I switched up R1/R3 with R17/R21! No wonder it sounded like shit. Anyway, I’ve fixed it now and it sounds glorious. Thank you for putting up with my stupidity and I’m sorry for wasting your time.
Rock on!
Peter

[pmjennings]

Thanks,
In calibration mode, I was able to even out the response of the hi/lo filters. When I first engaged calibration mode, the lo side was almost inaudible. After about 20 half turns of the lo adjuster, it was about equal level with the hi side. With the gain trim pot was set at 40K, the volume was good, but the muffled tone was still an issue. I tried adjusting the tone pots and the gain pot up and down to varying degrees to get a good balance, but there was no setting where the muffled tone totally disappeared.
The tone isn’t bad, it’s just not the tone I was expecting. I’d really like the tone to have clarity similar to that of the bypassed tone, but with tremolo. Is that what I should be expecting from this pedal? Are my expectations unobtainable?

BTW, my test rig is 2 P90s into a tweed Champ. I get the most muffled and compressed tone when I play through the neck pickup by itself. Not sure if that helps.

Thanks,
Peter

[pmjennings]

Brach

Thanks for the reply! It was never actually working correctly. The sound I was getting when I replied in January was low and muted, but I was just happy that it was working. I set it aside after noticing the volume discrepancy planning to tackle the problem later. Later is now!

So, you were right that gain wasn’t the issue. I pulled the trim pot and wired in a guitar pot. I got volume all right! And way too much gain. So, I put the gain pot back in and focussed on the hi/lo filter pots. Turing them both up is now giving me the correct volume level – equal to the bypass volume – but when I A/B the tone of the tremolo against the bypass tone, the tremolo is very muffled. I’ve adjusted the filter pots every which way – and the DIP switches – but the tremolo tone is always muffled compared with the bypass tone. Is there any way to get the same level of clarity from both channels?

Oh, and I also checked and reflowed all the solder joints. They all look good to me.

Thanks for your help!

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