Sanyo M7770K - Barely any sound

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alphgman

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Jan 1, 2013
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Atlanta, GA, USA
Picked up nice (cosmetically) mini boombox Sanyo M7770K. At full volume, sound is barely heard, only is one speaker, using either FM or AUX. Not louder than an iPhone with speaker off, laying on the floor... Before I take it in for repair, not even sure what that's going to be like, thought I'd ask here, if anyone has any suggestions for troubleshooting. I haven't tested any components yet, not that knowledgeable with electronics, but will give it a try... One of the areas on the circuit board (named "Radio Tuner P.C. Board" in the service manual), had wax like substance on it, maybe something leaked out. I have circled the area in red in the attached picture. After cleaning it off, no change. If I yank on wires between the boards, the second speaker can be heard but still very low volume with the volume control turned all the way up. Trying to think what's next. I'm not bothered with radio or the tape not working for now. Having AUX only, would be just fine for now.



Thanks much for any thoughts!
 

baddboybill

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Jul 14, 2009
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alphgman said:
Picked up nice (cosmetically) mini boombox Sanyo M7770K. At full volume, sound is barely heard, only is one speaker, using either FM or AUX. Not louder than an iPhone with speaker off, laying on the floor... Before I take it in for repair, not even sure what that's going to be like, thought I'd ask here, if anyone has any suggestions for troubleshooting. I haven't tested any components yet, not that knowledgeable with electronics, but will give it a try... One of the areas on the circuit board (named "Radio Tuner P.C. Board" in the service manual), had wax like substance on it, maybe something leaked out. I have circled the area in red in the attached picture. After cleaning it off, no change. If I yank on wires between the boards, the second speaker can be heard but still very low volume with the volume control turned all the way up. Trying to think what's next. I'm not bothered with radio or the tape not working for now. Having AUX only, would be just fine for now.

https://boomboxery.com/forum/uploads/alphgman-5242/img_1688.jpeg

Thanks much for any thoughts!
Wow you messed up. Should have asked before you touch it. The wax you saw was to keep the tuner coils in specific place. It was put there during manufacturing. Tuner pretty much might be shot now that you messed with it. As for no sound you may want to get some deoxit or switch contact cleaner and clean switches. I highly doubt it will work but that's your first step to narrow issues down
Sorry couldn't help more. Good luck ;-)
 

skippy1969

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May 6, 2009
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Yup I have to agree with Bill,it's screwed. :thumbsdown:
That wax is there for a reason,to keep the tuner stuff in an exact placement so it will work.
You'll probably never get it back the way it is supposed to be...... :sadno: :-/
 

alphgman

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Jan 1, 2013
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Atlanta, GA, USA
Deoxit made the other speaker come on, but still almost no volume. If I plug in headphones, they work fine, volume control, balance, and tone work. Could it be something with just the speakers?
 

baddboybill

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alphgman said:
Deoxit made the other speaker come on, but still almost no volume. If I plug in headphones, they work fine, volume control, balance, and tone work. Could it be something with just the speakers?
Spray some deoxit it headphone jack and work plug in and out. The jack could be dirty or or even rusty causing bad contact to speakers. You may need to use sand paper. If that's not problem it could be speakers blown :-)
 

BoomboxLover48

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Dec 3, 2010
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baddboybill said:
alphgman said:
Deoxit made the other speaker come on, but still almost no volume. If I plug in headphones, they work fine, volume control, balance, and tone work. Could it be something with just the speakers?
Spray some deoxit it headphone jack and work plug in and out. The jack could be dirty or or even rusty causing bad contact to speakers. You may need to use sand paper. If that's not problem it could be speakers blown :-)

Head phone jack could be the culprit like Bill said! :yes:
 

alphgman

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Jan 1, 2013
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Atlanta, GA, USA
Ok. Just tried that. The area on the circuit board where all the jacks are looks very dirty compared to other parts, some metal contacts have green residue. I have used plenty of deoxit, but no change to the sound level at all. I guess I will see if I can figure out how to use a multimeter to test the speakers next. Thanks so much for your help! I'd love to get this boombox working again..
 
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