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Head phones all of a sudden not working
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Head phones all of a sudden not working

by analogstatic on Fri Aug 04, 2006 4:00 pm

Hey all! #179 has been working pretty well for the past couple of months. Then all of a sudden the tempo knob stopped working. Turning it didn't do anything. I opened it up and just rehit the solder joints, thinking it was a cold solder joint or something that got messed up getting banged around.

Well, that fixed the tempo knob, but now all of a sudden the headphone's aren't working. Mix-out works fine. I checked the ribbon cable and was able to get some sound from applying a tiny voltage from the main board, so I know that's OK. Did some testing according to http://wiki.jonnay.net/x0x/headphonetesting. It looks like almost all the pins are getting about 40mV *DC* when grounded to R179. Am I testing something wrong or is my LA4140 messed up?

I rehit all the solder points for the headphone section just to be sure everything was gravy, but that didn't do the trick. Neither did cleaning the area with some flux remover. I know I've messed something up, just don't know where to look if all my values for LA4140 are messed up. Thanks in advance.
analogstatic
 
Posts: 25
Joined: Tue Feb 07, 2006 10:04 am
Location: Lexington, KY

by analogstatic on Fri Aug 04, 2006 4:29 pm

oh i've got 179 on the brain this is actually #197. Thought I'd clarify, lest the owner of #179 think they had been duped!
analogstatic
 
Posts: 25
Joined: Tue Feb 07, 2006 10:04 am
Location: Lexington, KY

by guest on Sat Aug 05, 2006 2:32 am

if you take a set of headphones
and ground the sleeve
and put the tip to pin6 of ic14
can you hear any sound

is there 6v on pin7 of ic14
if not
check to see if there is 6v on the ioboard
the ribbon cable may be broken
somewhere in the middle
guest
 
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Joined: Fri Feb 17, 2006 5:35 am

by analogstatic on Sat Aug 05, 2006 9:22 pm

Yep that was it. Pesky ribbon cables. I should've just done a continuity check on each wire in the begining. Wasn't thinking. Thanks guest!
analogstatic
 
Posts: 25
Joined: Tue Feb 07, 2006 10:04 am
Location: Lexington, KY

Please be positive and constructive with your questions and comments.