So I plugged a 9V AC into my rebote OopS

Started by Wild Zebra, September 29, 2006, 01:34:16 PM

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Wild Zebra

  Well I wasn't paying attention and now it doesn't work.  Can I begin by assuming its either the TLo72, PT2399, or the 5V reg?
I stll get signal through it but no delay.  Before I order or buy more parts just wondering where to start.  If I touch the PT and TL I get some buzzing and if I touch the 5V nada.  And if I take the 5V out it sounds the same clean signal.  So I'm just guessing, I burned that out?  I recken I can get a 5V(maybe) and TL072 at my local elec store. So I can start there.  A question I have is can you burn out resistors and caps?  I just figure I burned an IC and there all socketed so replacing is no prob. 
"your stripes are killer bro"

wcampagner

Hello,

I'm my opinion some of the IC's must have burnt... i think resitors and capacitors are much harder to burn...

If i were you i would start to change the TL072 and the 7805 first because they are much cheaper than the PT2399... but i think the problem is on the 7805 or on the PT2399 as you said you still can bypass the clean signal...

Don't you have a multimeter?? You could measure the voltage on the 7805 to check if there is 5V in it... Or if you don't have you can test the 7805 putting a LED with a resistor on the 5V terminal and check if the led is on...

Thanks,
Wagner.
Thanks,
Wagner.

DuncanM

I remember reading somewhere recently that you can kill the 78xx type regulators if their input voltage is higher than their output voltage. By putting 9v AC on the input you might achieve this - you have two 47uF caps on the output side acting as voltage regulation against one 47uF cap on the input side...

I'd go for the regulator first too.

Wild Zebra

  Well I bought the 7805 and Tlo72 last night to no avail.  So I'm here at work ordering a couple of PT2399's.  Hope they get here by friday!  And I hope thats what it is.  I had to buy the NTE replacement for the 7805, but it looked Kosher.  May my local electronics store is expensive.  7805 small bear 41 cents, NTE replacement my store just over 2 dollars OUCH!
"your stripes are killer bro"

H.Manback

#4
I know it's too late unfortunately, but these kind of things make me realize polarity protection can be a life saver.

http://geofex.com/Article_Folders/cheapgoodprot.htm

I made one recently, I could fit it on perfboard in a 5x6 hole square. I don't think I'll ever be building anything again without it.

Good luck fixing it. I suspect the delay chip died indeed. As far as I know digital chips (and opamps) do not take reverse voltage very well..

R.G.

I'm sorry for your loss.

You accidentally did the single most destructive thing that can be done to an effect with a power jack on it. Putting a 9Vac plug into a 9VDC jack will kill not only the effect inside, it will also kill the simple and easy reverse-parallel diode protection circuit. This happens to commercial effects a lot now that a few companies have made effects with the same physical power plug on them but 9Vac coming out of the adapter.

Frankly, if any semiconductor in there lived, it is just good luck. I would consider them a total loss and replace all of them, as well as the electrolytics to avoid ordering a few parts, then finding out that I needed more.
R.G.

In response to the questions in the forum - PCB Layout for Musical Effects is available from The Book Patch. Search "PCB Layout" and it ought to appear.