3 in 1 out mixer issues...

G

gwyador

New member
I bought the 3-in to 1 out mixer and have built it up but I am getting distortion and a gate like cutting out from all channels... Has anyone else experienced this? I am wondering if I can get the schematic since you have not posted the build documents on this pcb yet... Yes it is a simple circuit but I am not sure where I have gone wrong... I get sound from all inputs it is just distorted and cuts out as it fades on all channels... I thought maybe I had a bad chip and since I socketed them I swapped the output chip and no change... at any rate if you can provide me the schematic for this I can troubleshoot further... If anyone else has any odeas I am open as well... could a bad solder joint somewhere cause this? thanks! Bryan
 
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The schematics for both the Splitter and Mixer have been uploaded elsewhere on the forum, (in another thread I posted a link to them just yesterday) you'll find them if you SEARCH.

SOP for a trouble-shooting thread is to post well-lit pics of your build including front/back/all wiring.


*BTW, I've tried 3 times now to edit this post to add links to the schematics, and it's not working, but the link to the search engine posted just fine.
 
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power rails to all chips look good! not sure what would cause the gate-like effect I am hearing... very curious... I am looking for shorts on the PCB at this point but a schematic would really help!
 
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I really do not know what pictures will help with but here goes... As I said, rails look good but I swapped the tl072's out for tl972's in case the signal level was somehow reaching close to the rails and I found if I turn the volumes down about halfway with the 972's installed I can get continuous sound but if I turn it up past about halfway I lose sound... I would have thought it was an op-amp issue except for that symptom. Was this mixer designed for line signals? If so, are the caps there to gate the signal below a threshold? I'm tempted to remove them and see. does anyone have thoughts on this?
 

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Pretty sure (99.8%) this mixer is meant for instrument-level.

Danged if I know what the problem is. I was going to suggest re-seating IC #3 (3rd from left), but if you've already swapped out the ICs...

A short/partial-short under one of the IC-sockets? Perhaps the one handling the actual mixing, as you said the problem's happening on all channels.

The fading indicates it might be a problem with a cap, so peut-etre a bad cap? That could also explain the distortion, a bad cap.


I'm not a good trouble-shooter, I know, but people tell me I'm trying...
 
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