Clarinot gettin' hot!

[bloxstompboxes]

The pedal will only draw what it needs in current from the PSU. The PSU will not just forcibly feed 500mA into it. Have you tried flipping the reg as suggested yet? If it and the ICs are hot, then I would say they were definitely damaged by now. They may still work, but I would say that their lives have been significantly shortened. Try the reg the other way around and then, if it works, remember that when swapping all the ICs that got hot.

[jonnygreentrees]

Yep have swapped the reg around and it's still getting really hot   

If it helps at all my homemade vactrol is lighting up when I play into the circuit.

Is it possible that initially orientating it the wrong way round has damaged the reg causing it to get hot the correct way round? Or does it not workl ike that?

[greaser_au]

Is it possible that initially orientating it the wrong way round has damaged the reg causing it to get hot the correct way round? Or does it not workl ike that?

If it has been powered in reverse at all, you should consider it unserviceable.   Vout>Vin will very likely destroy the device. Old datasheets used to specify using a reverse diode across the regulator. Depending on the failure mode it may have applied unregulated votage to the devices it should be regulating for.

Also note that if there is something that is drawing excess current from the 5V rail, the 78L05 will shut itself down when it gets hot (which doesn't take much), even if it is working correctly.

As discussed previously, you might measure the voltage at pin1 of the PT2399 (with circuit ground as the reference) to confirm regulator operation.

david

[jonnygreentrees]

great thanks for all the help so far will try with the new components and report back

[duck_arse]

what is the output voltage of the wall wart?

[jonnygreentrees]

9V

[jonnygreentrees]

OK so just stuck in a fresh reg and it's still getting really hot, too hot to touch.

On 9v in I'm getting 11.82v

On pin 1 of the pt2399 I'm getting 4.87v

The sound the pedal is making is a horrible buzz but that could be because I still have the old ICs in which I may have fried

[Cozybuilder]

The wall wort should not be outputting close to 12V- theres a problem there that needs to be resolved.

[jonnygreentrees]

I'm testing using DC on my DMM, is that correct?

[Cozybuilder]

Yes, DMM should be reading on DC. It kind of sounds like someone slipped you a 12V wall wart instead of a 9V.

The data sheet for a National Semiconductor 386 shows 12V max supply voltage, you might have a problem with that chip too.

http://www.ti.com/lit/ds/symlink/lm386.pdf

[jonnygreentrees]

it's ok I bought a replacement 386 too

I'll bin the wall wart, could 12v coming in be enough to overheat the reg like that?

[bloxstompboxes]

I think the max Vin for the 78L05 is something like 30V, so 12V in should not cause an issue to the regulator. It might probably if it was with the wrong polarity though. Check the datasheet on your regulator to be sure though.

[Cozybuilder]

I think you should check C8 for leakage. Something is making the regulator heat up, which you would think is a short or low resistance, and a leaky or shorted C8 looks like a reasonable candidate.

[jonnygreentrees]

Sorry for the stupid question but how do I test C8 for leakage?

Cheers

[duck_arse]

this may also sound like a stupid question, but is the wall wart DC output or AC output. AC would explain the buzz, the hot reg, the 11V8 too, probably.

test a cap for leakage by measuring the resistance across the leads out of circuit, or the DC at either end in circuit and powered.

[jonnygreentrees]

shit it is an AC adapter! Can't believe I've been so stupid!

[jonnygreentrees]

So it isn't overheating with a BOSS DC adapter, needs a bit of debugging as it only works when I press on the PT2399 but that's just some dodgy soldering.

I have used this adapter briefly with other pedal builds to test them will I have damaged them?

[bluebunny]

It's possible.  I guess you will just have to test them with the good DC Boss PSU.  Good luck.

[Kipper4]

Repost some voltages Jonny let's have lookie see.

[Cozybuilder]

Entertaining reading, I think all of us learned (or relearned) from this.