Build Your Own Clone Message Board

Hello,
I bought a Version 1 Analog Chorus over a year ago and assembled it and had it work correctly on the first try! It worked wonderfully for months, but eventually the binding posts came unglued and the pcb was loose and started banging up against the chassis and the pedal stopped working. I took it apart and completely rewired and reheated all of the solder joints and now the bypass works and the LED works, but only when the pedal is in bypass mode, which was the case even when it was working. When I switch it on, my signal becomes amplified, but there is no effect and when I turn the trimpot to either of its extremes a high pitched squeel eminates from my amp. I also tried to flex the pcb slightly while the pedal was on to see if I could force contact where the circuit might have been open. This also did not work.

Enclosed are some pics that I hope will help you guys diagnose the problem. I hope you guys can help me with this one cuz Im stumped.

Thanks,
Jud.

Sorry, that first pic was way out of focus. Here are some better ones.

You have something blocking your signal; either a bad joint or a component went out. Best way to diagnose that is to take voltage readings from the chips and trace the signal path with a signal tester. Are you able to perform any of those things?

Yes. I have a multimeter. However, Ive never done this before. What is the best way to check the signal path? Do I check the voltage or resistance? Is it enough to touch one tip to the dc jack and the other to the chip terminals? Sorry. Im still new at this.

Start with taking voltage readings from just the LM chip. You only take voltage readings from active components, like chips and transistors. Here's a tutorial.

http://www.ladyada.net/learn/multimeter/voltage.html

Alright. I took the readings for all the chips. I was not sure how to type all that info coherently so I just made an illustration and took a picture of it. The LM chip had some contacts that seemed to fluxuate between voltages so I took the voltage that they seemed to linger on the longest or most often and marked them with an *asterisk*.

You should have about 9 volts on pin 4 of the LM324 and 0 volts on pin 11. That appears to be reversed on your readings. Your AC adapter wiring seems fine, but what power supply are you using? You should have a negative center supply. Is that what you have? What is the voltage at the 'pos' pad on the pcb? Have you tried a battery?

Yes, I am using a battery rather than a power supply. Could it be that I have two resistors mixed up that would make those voltages switched? and what would make the LED come on only when the pedal is in bypass mode?

Oh, and the voltage at the POS is 9.61.

You've got a short somewhere that is putting supply voltage on the ground rail. Your soldering doesn't look great, and the excess splatter and flux may be causing the short.

Check out the soldering tutorial in the confidence booster lounge, along with Stephen's tips for a successful build, and make sure your soldering is up to snuff. Remove all chips from their sockets, make sure your soldering iron tip is clean, shiny, & hot, and go back over your solder joints again. Some of them need more solder. When you finish up re-doing the soldering, clean the bottom of he pcb with rubbing alcohol, acetone, or something along those lines.

I don't know how you can have the led on in bypass mode. You need to test the switch. Search the forum for a tutorial.

Alright. The switch is bad. Thanks for directing me in the right direction. I am going to order a new switch and as soon as I get it in I will report back to let you know if its working. Thanks.

Good deal! It's always good to chase down something that's definitely wrong.