Flatline Compressor works w/ battery, but fries IC's when DC-powered

[iiimonfire]

Last week I finished a successful build of the John Hollis Flatline Compressor (SabroTone vero layout).

Everything was working beautifully as I tested the board with a 9V battery.

Then over the weekend I boxed it up, hoping to finish up the build. I used two mono jacks, and a two-pin DC jack with the plastic covering to isolate the power supply from the enclosure. I wanted to squeeze it all in a 1590A, so no battery + battery snap was intended for this build. Here's a photo of the incomplete build, shown here are most of the elements I used - I want to note the DC jack, as it's different from the ones I normally use from Tayda.
For off-board wiring, I used the Tagboard template.
And for wiring the 3PDT switch, I used the DIYStrat template.


So here's the problem:
I connected it to the 9V power supply on my pedalboard to begin testing, and it stopped working entirely. No LED, no circuit, no sound. The power supply is currently powering my other pedals, so no problem there. During a thorough round of debugging, I replaced the IC, and then re-connected a battery snap with alligator clips to the correct endpoints on the DC jack (disconnecting the daisy chain from the pedal, of course) - and all was working again. Then I removed the battery, connected the power supply again to the DC jack, and nothing was working - this time I noticed the IC started was hot to the touch. I disconnected everything, removed the IC and it was indeed hot and smelled a little. I reconnected the battery snap as before, replaced the IC, and as expected nothing worked again.

So connecting to a DC power supply seems to be shorting out the circuit. I've checked and double-checked that all of my off-board wiring is okay. I am currently stuck with 3 burned TL072's, and will have to wait till my next order to get a few. In the meantime, I'd appreciate if anybody can help me figure out what I can do to take care of this problem.

Is it because of the DC jack I used?
Or is it because I mixed-and-matched the 3PDT wiring with the rest of the off-board wiring concept?
Or maybe I have a short somewhere else? (but this was working with a battery+battery snap...)

I'm a bit of a noob still, but appreciate any help I can get. Thanks!

[Armo]

If IC getting hot and no LED chances are you have your +/- wrong way round. I built this one years ago but ended up using a vactrol instead of an LED/LDR.

[iiimonfire]

Nope, I do have the LED the right way around - both the indicator and the LED that is part of the DIY vactrol. I've retraced the entire vero and everything appears exactly as it should in the verified layout.

Here's how I isolated the problem:

1) Tested IC on Battery power.
Results:
- Indicator LED working
- Circuit is working as expected

2) Tested same IC, now on DC power.
Results:
- Indicator LED not working
- IC-1 heats up like a bastard
- Circuit does not output audio

3) Tested same IC, again, back on Battery power.
Results:
- Indicator LED not working
- Circuit does not output audio

Conclusion: DC power fried IC #1

4) Switched out IC for new IC, remaining on Battery power.
Results: Indicator LED working again. Circuit outputs audio. (same as #1)

[slacker]

I think what Armo meant is your DC jack is wired backwards, that's the most likely thing to kill an IC. If you've got a meter remove the IC and power the pedal up with DC and measure the voltage between the +9v and ground tracks on the board, you'll probably find you're getting -9 Volts, if you are reverse the connections to the DC jack.

[anotherjim]

Certainly looks like reverse power connection. The suggestion is that what you think is the + pin of the DC jack isn't. Of course it works when you wire a battery to it, because the + wire of your pedal really is the + wire, but that isn't the wire the DC supply is putting +9v on! The guitar pedal DC supply plugs are centre pin negative, the opposite of most other power supplies out there which are centre pin positive.

Ok, so you socketed the IC's - will this teach you to try it without the IC's so you can DMM test the voltages on the supply pins at the socket first in future ?

[ElectricDruid]

Ok, so you socketed the IC's - will this teach you to try it without the IC's so you can DMM test the voltages on the supply pins at the socket first in future ?

Aah, how many times have I learned that lesson?! Enough now, finally, but "more than once" is charitable

Tom

[iiimonfire]

Wow! Thanks everybody! This definitely sounds like the culprit. I'll give your suggestion a try over the weekend and will let you know how it turns out.

[iiimonfire]

Update:

Yep, that did it. I measured as instructed and indeed got -8.99V. Rewired the DC jack, measured, and subbed in a working TL072 from another build, and all is in working order.
Thank you guys for your explanations!

-D