My pedal died... Crap!

[StevenJM]

I built a GGG companion fuzz months ago and it's been working great until today.

I was reorganizing some pedals tonight, using a boss daisy chain to power the pedals.  The companion fuzz was already plugged in, but as I was plugging in another pedal, the tip of the daisy chain hit the enclosure causing a small spark and all the pedals turned off for a second.  I'm not sure if this is the cause to my issue or not, but I'm wondering if maybe I caused a little power surge.

All my pedals work fine except the companion only works in bypass mode now.  One of my capacitors is only rated at 10v... Do you think the surge maybe blew out the cap?  I have some 16v ones of the same value laying around, maybe I'll try those.

Ugh, maybe it's time I buy and learn how to use a multimeter on pedals.

[StevenJM]

Bump, any help would be appreciated.

Thanks.

[GGBB]

Here's a good place to start:

http://www.diystompboxes.com/smfforum/index.php?topic=55003.0

[StevenJM]

Here's a good place to start:

http://www.diystompboxes.com/smfforum/index.php?topic=55003.0

Thanks!  great thread!  From reading this I'm hoping I was right and I blew the 100uf 10v cap.  Since I have 100uf 16v already

[Paul Marossy]

Here's a good place to start:

http://www.diystompboxes.com/smfforum/index.php?topic=55003.0

Thanks!  great thread!  From reading this I'm hoping I was right and I blew the 100uf 10v cap.  Since I have 100uf 16v already

Does your GGG pedal have a reverse polarity protection diode? I don't see one on the schematic. Sounds like you fried some active components by accidentally shorting out your power supply. I really doubt it's your 100uF cap.

[GGBB]

^^^ +1

The 100uF cap is a typical power supply filter cap connected between +9v and ground.  If it fried you might actually be able to see that visually (blown top, burn marks, bulging).  Otherwise, you can easily test it for being shorted with a multimeter.  If it's not shorted out, even if it has failed it wouldn't keep your pedal from working so you likely have some other problem(s).

[Paul Marossy]

The reason I think it's not the 100uF cap is that it would have to be in a reverse polarity situation for more than just a few seconds to get blown. It only takes a second to blow active components that aren't protected from reverse polarity however.

[GGBB]

I agree Paul.  For the record, the GGG schematic doesn't show them, but the bill of materials and parts layout both have the 100uF power filter cap and the reverse polarity diode.

[Paul Marossy]

I agree Paul.  For the record, the GGG schematic doesn't show them, but the bill of materials and parts layout both have the 100uF power filter cap and the reverse polarity diode.

OK, good to know. That makes this event even a little more unusual...

[StevenJM]

Man what else could it be?  Nothing looks visually burned when I opened it, it was working fine prior the "spark" that's why I'm assuming that's the cause.  I checked all the wires and my connections are all strong.

Thanks for looking into it for me though, it's a head scratcher.

[Paul Marossy]

The only way you'll figure it out is to get a DMM and measure voltages. Then you can determine what is getting power and if the voltages look right.

[StevenJM]

Walk me through it quick . I've used one to test guitar connections but never a circuit board...

Should I plug the power supply into the pedal, and just test which active parts aren't getting power?  Black to the ground and red to the positive side of the cap?

[Paul Marossy]

You're getting the idea...

[StevenJM]

well i switched out the 100uf 10v cap and still doesn't work.  Now the LED isn't even working.  Still works when bypassed though.

bummer.

[aron]

I love the audio probe as described in the debugging page. I would "listen" to Q1's base, Q2's base, Q3's base. That will tell you what stage is not working. Then figure out the problem from there. If the LED is not working, it could be some sort of power problem. Check the voltage going to the LED.

[StevenJM]

I love the audio probe as described in the debugging page. I would "listen" to Q1's base, Q2's base, Q3's base. That will tell you what stage is not working. Then figure out the problem from there. If the LED is not working, it could be some sort of power problem. Check the voltage going to the LED.

thanks i'll read through that page.  this has got me pretty bummed out, but i'll figure it out.  The pedal worked great since I built it in February...  I'm going to go buy a tester tomorrow so hopefully this weekend I can get it working again.  The LED was working last night, but now today, I'm getting nothing.  I'm thinking its a power problem, but i'm not too sure what i'm really checking.

[newfish]

I love the audio probe as described in the debugging page. I would "listen" to Q1's base, Q2's base, Q3's base. That will tell you what stage is not working. Then figure out the problem from there. If the LED is not working, it could be some sort of power problem. Check the voltage going to the LED.

thanks i'll read through that page.  this has got me pretty bummed out, but i'll figure it out.  The pedal worked great since I built it in February...  I'm going to go buy a tester tomorrow so hopefully this weekend I can get it working again.  The LED was working last night, but now today, I'm getting nothing.  I'm thinking its a power problem, but i'm not too sure what i'm really checking.

Might be worth re-flowing all of your solder joints.  Intermittent faults are the hardest to find.

With your DMM on resistance, there should be 0 ohms (or as close to as your meter will show) when measuring between both ends of your pot and switch wires.

You can also use this function to check that your bypass switch is working correctly (as in, you'll get a '0' reading between one set of contacts, and not the other - the vice versa).

Hope you get it sorted.

[StevenJM]

I don't think it's a soldering issue, but reflowing everything couldn't hurt.  The most frustrating part is that it was working fine for so long, including that night.  Then suddenly it just stops. 

I'll get a tester after work today and trace the power circuit and see if I can find my problem in there.  If not, I'll just keep looking and ask questions here.

Thanks for all the help so far everyone.

[Paul Marossy]

The Audio Probe has kept me from going nuts more than once!
http://www.diyguitarist.com/PDF_Files/DIY-AudioTester.pdf

[nosamiam]

Are you running it with a battery now? Could it be that the power supply is damaged? I dunno... I'm kind of a dummy with this stuff.