Zander Tape Deck - white noise / hot chip

Started by E17, January 29, 2018, 04:50:35 AM

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E17

Hi all.

I hope someone can help me identify something silly or point me in the right direction.

I was given a Zander Tape Deck kit for Xmas. It's a PT2399 delay with a modulation switch. It's my first build.

So, the issue is in the video. The pedal passes audio in bypass and on engaging the pedal, i just get noise. The knobs don't make any determinable difference to the noise. The LEDs light up as they should do with the 3PDT switches and the LDR/LED arrangement is pulsing like it should.



I've noticed that one of the TL072 chips gets super hot. I've reflowed solder around the resisters here. No change. Pictures of the build are below. I've bought a multimeter to debug but it arrives in a few days and i need to learn how to use it!

Is there anything obvious you can see here please?

Thank you!
Dan





tonyharker

The upper TL072 in the second picture and the PT2399, are the wrong way round.

E17

Thank you! Just as I was coming back here to post, the guy from Zander replied with the same advice (he is very helpful and it is much appreciated) - thank you so much. I'll post here again once I remedy this and we'll see how it goes then!

bluebunny

If those two chips aren't zorched by being in backwards, then trying to desolder them non-destructively will probably finish them off!  :-\  Consider using sockets in future.  And buy a couple of replacements while you're filling the cart.  ;)

These learning opportunities are such fun!  ;D  (We all do it, btw.  Initiation complete...)
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E17

Thank you - I had to wreck the chips getting them out and spent the night trying to clear the vias in the board. Got new ICs on the way and will be socketing any ICs on future builds!

I'm now wondering how much a single PCB can take before it's cooked.  :(

bluebunny

Quote from: E17 on January 31, 2018, 08:24:34 AM
I'm now wondering how much a single PCB can take before it's cooked.  :(

Not too much more.  Eventually you'll start lifting pads...  :-\
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Ohm's Law - much like Coles Law, but with less cabbage...