Newbie diagnosing 8-Ball

[pryonisys]

Hey guys, this forum and the projects shown on it are great, lots of good help and ideas.
I'm very new to this and for some reason chose the Egghead and 8-Ball as my first two pedals to try, neither of them are working, but my real question is on the 8-Ball.
I made a test box to test out the pedal and hooked it up to test and I don't get any guitar signal through, I do however get something that kind of sounds like a pulsing heartbeat.
Probably one beat every minute or so.  Has anyone ever had this happen?  Thank you for any help with this.

[selfdestroyer]

First off, welcome to the forum. The 8-ball is a great circuit and it sounds like your one the right track by trying the pedal on a testing rig before you boxed it up. I do suggest you take a look at this post: http://www.madbeanpedals.com/forum/index.php?topic=902.0 and see if you can add a little more info about your problem so we can help you.

Does your test rig pass audio when the effect is bypassed?

Some of the first things I would do is to check and make sure all electrolytic capacitors have the correct orientation. Also use a digital multi meter if you have one to ensure you are getting 9v from your power source.

Cody

[playpunk]

If you have already wired up your test rig, I would suggest plugging your guitar into the input and the output into an amp, and then clipping the alligator clips for input and output together, and checking to make sure signal passes through the testing rig when no effect is in it.

After you do that, use a multimeter to make sure that you are getting +9v from your DC jack.

Don't ask me how I learned both of those little steps. Also, don't ask me how I got the soldering iron shaped scar above my left eyebrow.

[pryonisys]

Hey guys thanks for your help here is a bit more info following the link you gave me (thanks for that by the way)

(1) Project Name - 8Ball
(2) General description of the problem - Pulsing sound, but no guitar thruput.  Led that is attached to the board does not light and when power is applied one led that is being used in place of a diode flashes very briefly then goes off.
(3) Steps that you have taken to try to resolve the issue - hooked it to a testing box, tested that the input and output of testing box worked by attaching the input and output for the tester together successfully.  Checked the polarity of the dc on the tester and everything looked good.  Hooked circuit back to the tester and went back to having no signal through and the led did not light.
(4) List any substitutions you used for parts/values - none

[HKimball]

I don't have a lot of great advice on this, but my cro-magnon approach is to look at the schematic and start at the output - I use a screwdriver and I tap the whole circuit starting at the output jack. The result is a loud clicking sound if the circuit is working and nothing if it isn't... I mean, at the very least because I'm cross referencing everything to the schematic I might come across a turned around diode or a misplaced resistor.

FWIW, I don't "rock it before you box it" - I probably should but so far I've gotten away with it.

I don't know if this is true for you, but my biggest problem, 10 times out of 10, is a cold/incomplete solder joint. Since I started using solid copper wire the problem his dissipated somewhat but for more complicated things (e.g. perfboard builds with multiple circuits and switchable buffers etc) It's still a problem.

The 8ball is a straightforward circuit so it should be simple enough to troubleshoot... You don't have any sound at all so I would check the clearance of the potentiometers above the board. This has been an issue for me especially with the pcb mounted builds. I would also check to make sure the diodes are wired in the correct orientation - the 1n4148 diodes are super easy to identify but the LEDS can be tricky. Does it make sound when you toggle between the two positions?

[selfdestroyer]

Hey guys thanks for your help here is a bit more info following the link you gave me (thanks for that by the way)

(1) Project Name - 8Ball
(2) General description of the problem - Pulsing sound, but no guitar thruput.  Led that is attached to the board does not light and when power is applied one led that is being used in place of a diode flashes very briefly then goes off.
(3) Steps that you have taken to try to resolve the issue - hooked it to a testing box, tested that the input and output of testing box worked by attaching the input and output for the tester together successfully.  Checked the polarity of the dc on the tester and everything looked good.  Hooked circuit back to the tester and went back to having no signal through and the led did not light.
(4) List any substitutions you used for parts/values - none

Thanks for the info. Also add a few photos of both sides of the PCB. This will help identify any physical issues.

Cody

[midwayfair]

It sounds like one of your electrolytic capacitors is backwards. This would kill the voltage on the power supply rail and your project would create a pulsing sound as the cap/DC supply cycles. It's not necessarily the only thing that's wrong, but it's the first thing I'd look for.

Go back to the troubleshooting thread and continue reading. Jacob explains how to take voltages on your circuit. You're going to need to use your multimeter to diagnose and correct this. You can audio probe after confirming that your voltages are correct.

Your LED on the board won't light unless it's hooked up to the switch; I just want to make sure you're aware of that.

[pryonisys]

It sounds like one of your electrolytic capacitors is backwards. This would kill the voltage on the power supply rail and your project would create a pulsing sound as the cap/DC supply cycles. It's not necessarily the only thing that's wrong, but it's the first thing I'd look for.

Go back to the troubleshooting thread and continue reading. Jacob explains how to take voltages on your circuit. You're going to need to use your multimeter to diagnose and correct this. You can audio probe after confirming that your voltages are correct.

Your LED on the board won't light unless it's hooked up to the switch; I just want to make sure you're aware of that.

I did not know this about the LED, thanks for letting me know, I'm going to try these steps once I make it home from work.  Thanks for all of your help thus far guys.