Did I just destroy my Bluesbreaker?

phintze · January 30, 2009, 09:11:21 PM

I finished wiring up my GGG Bluesbreaker this afternoon. When I was ready to test it out, I realized that I didn't have any 9V batteries, so I grabbed a power supply from my "box o' cables." Unfortunately, I grabbed the wrong one - it was center positive. It was probably plugged in for about 15 seconds before I realized my mistake.

I tried it later with batteries. I switched it on and the LED flashed once and went out. Did I fry something? A diode, maybe? How do I check that?

railhead · January 30, 2009, 09:38:43 PM

Is any sound coming out?

phintze · January 30, 2009, 09:56:11 PM

Nothing. I'm currently checking for continuity. The bypass checks out with a meter, but no signal is passing through.

railhead · January 30, 2009, 10:19:00 PM

Do you have an audio probe by any chance?

kurtlives · January 30, 2009, 10:27:34 PM

Op-amps can die pretty quick...

Try a quick op-amp swap, I find that usually works.

phintze · January 30, 2009, 10:28:22 PM

I don't have an audio probe.

I'll try an opamp swap and see if that works.

phintze · January 30, 2009, 10:48:36 PM

Actually, the bypass doesn't check out with the meter. I think that the switch may be bad - it was an old one that I had lying around. I can't test another one out, since my order of 3PDT switches is still in the mail. $:-\$

I could hardwire it to see if the circuit works, but I don't feel like doing that right now. I'll probably mess with it again tomorrow.

railhead · January 30, 2009, 10:53:41 PM

Well, it worked well enough to flare the LED, so something happened. You could apply power to the LED (with resistance) from a battery and see if you get anything, then you'll know whether or not the LED burned out. If the LED works, you prob fried the OA -- the diodes should be fine.

petemoore · January 31, 2009, 01:48:32 AM

Test the reverse polarity protection diode, maybe it did it's job and fried.
Basically or not, debugging is a square one deal.

sevenisthenumber · January 31, 2009, 02:06:37 AM

As stated, check the 1n4002 diode directly below the 9v in on the pc. Maybe it did it's job....

tehfunk · January 31, 2009, 03:06:37 AM

Quote from: railhead on January 30, 2009, 10:19:00 PM
Do you have an audio probe by any chance?

I am sorry but I have to suggest this, you might need it in the future and it will be very useful... it's also cool to hear how the circuit modulates your original sound as you follow along.
http://www.diyguitarist.com/PDF_Files/DIY-AudioTester.pdf
I just built it two days ago it's great. If you have heat shrink that's useful to cover the wire connections to the capacitor. Btw, credits to Mr. Marossy for that great file.

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Did I just destroy my Bluesbreaker?