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Kingslayer, really hot ic's and high pitch whine.

Started by jolly1423, July 25, 2013, 01:52:08 AM

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jolly1423

So I built two of these and wow, amazing pedal. Mine has been working great but the one I built for a friend worked great for months and then all of a sudden it has this awful high pitch whine when engaged. I checked it out and noticed the ic's are getting super hot, almost too hot to touch. Any thoughts on that, has anyone seen that before? 

jimilee

Pedal building is like the opposite of sex.  All the fun stuff happens before you get in the box.

jolly1423

1-.57      8-.85
2-.35      9-.68
3-0        10-.59
4-8.67   11-.46
5-0        12-.7
6-.55     13-.72
7-.69     14-.76

1-8.63            5-8.57
2-4                6-8.39
3-.01             7-8.17
4- neg. .11     8-1.02

8.71v going in

madbean

Make sure your charge pump isn't backwards (I've done it) or your electrolytic caps.
You should be reading -9v on pin5 of the charge pump. It may need to be replaced.

jolly1423

I double checked everything with polarity, it's all the correct orientation. It seems odd to me that it would work great for 6 months and then not. It would suggest to me that something from the outside world affected it, i.e. a surge, but I know the guy has been powering it with a Pedal Power 2 so that seems unlikely.

jimilee

You may want to start with the electros perhaps? Sound Somme like a surge as well. Are the electros rates above 18 volts? I built a pedal that has a charge pump in it recently and pretty sure I put 16 v electros in it and often wonder what is going to happen.
Pedal building is like the opposite of sex.  All the fun stuff happens before you get in the box.

jolly1423

They are all 25 or 50v except C23. Think that's the culprit?

midwayfair

Quote from: jolly1423 on July 28, 2013, 01:33:18 PM
They are all 25 or 50v except C23. Think that's the culprit?

I'd sooner suspect the charge pump and the Zener.

If your friend decided to see what happens when he powers the pedal on 18v, he could have blown both. The Zener would short to ground and then all your ICs would get hot, too.

jolly1423

Well, he says he only ever supplied 9v from the voodoo labs, maybe a wall wart once. He's a pretty honest guy. I think I'll just start by replacing the ic's, the zener, and C23 and see what happens. Thanks for the help thus far guys.

jolly1423

Is a tlc274acd going to be the same as tlc274? Smallbear has that one...don't recall where I bought them before. I think Mouser which is numbered tlc274bcn.

jolly1423

So I replaced the charge pump, no difference but replacing the tlc274 fixed it. I don't know what the deal was so I replaced the 9.1 zener and upgraded C23 from 16v to a 50v as a precaution. We'll see if it happens again! Thanks for your help guys  :)