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PostPosted: Mon Mar 13, 2017 9:56 am 
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Joined: Mon Mar 13, 2017 9:47 am
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Hey all,

Just finished the classic delay build and all I'm getting when the pedal is engaged is intermittent crackling. HOWEVER, my dumb self installed the op-amp backwards when I first powered it on.....

I only realized this because I could smell it...

I'm guessing I fried the op-amp? Is there a way to tell?


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PostPosted: Mon Mar 13, 2017 10:57 am 
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Joined: Wed Apr 26, 2006 5:14 pm
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Location: Truckee, CA
If you are getting sound in bypass but no dry sound in effect mode, something is wrong with the dry signal path, which the op amp is part of. If you installed it backwards and smelled burning, it is likely that it is toast and needs replacement. Do you have any dual op amps handy? It doesn't have to be the exact same chip.

If you want to check voltages, you should have about 9 volts on pin 8, 0 volts/ground on pin 4, and about 1/2 of the pin 8 voltage on the other pins.

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PostPosted: Fri Mar 24, 2017 3:04 pm 
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Joined: Mon Mar 13, 2017 9:47 am
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ok so i ended up getting a new op amp (TL072), and the signal is present when the pedal is engaged. However.......i'm not getting any delay except for a faint distorted single repeat if i play hard enough.

Could i have messed up the pt3299 ic in the process of smoking the op amp?


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PostPosted: Fri Mar 24, 2017 3:24 pm 
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You might have damaged the voltage regulator and/or the delay chip. Are you able to take voltage readings? We need to know the voltage output of the regulator and the input voltage at pin 1 of the PT2399.

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