[FIXED] JVC M70 - Right Speaker Whispering (Unable to cutoff)

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Dancorp

Member (SA)
Apr 13, 2017
127
10
18
Marseille, France
Hi everyone,

In advance sorry for the english, i'm just a poor frenchy :)
I restore my first boombox thanks to this amazing board.
Oxeded lever buttons, power switch, source switch... most of issues have been solved.
I still got one: i'm unable to turn off right speaker, it still whispering.
I'm also unable to fine increase the volume at start. it jump with a loud sound.
Lever have been cleared many times with a french elec. contact cleaner.
It sound like a ground problem, (when a touch the lever, i got like small impulsion in the speaker) I have already check solders without success

A video of the problem :
https://www.youtube.com/watch?v=ifhhY5pOpPg


Thanks in advance for your help

Dan

EDIT : Fixed ! https://boomboxery.com/forum/index.php/topic/26480-jvc-m70-right-speaker-whispering-unable-to-cutoff/#entry349597
 

Dancorp

Member (SA)
Apr 13, 2017
127
10
18
Marseille, France

Dancorp

Member (SA)
Apr 13, 2017
127
10
18
Marseille, France
i have to disassemble my M70 to get sliders sizes, pins localisation, the shaft... to check if i would be able to fit 3th party sliders on my boombox.
Of course that will be not easy to find the same shape or to fit it, but originals pots are not available anymore. this solution must be study.
 

caution

Member (SA)
Mar 25, 2014
2,498
334
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Boomboxery
When I was looking for M70 sliders, I did find some that had the B curve and a center tap, but either had different dimensions or pin locations, so even in the best situation, you will have to glue the pot into position and jumper the pins, and maybe also add a riser so it still sits at the right height.

As far as I know, no other boxes used the M70's sliders, unlike the M90 pot, which Toshiba and Panasonic (and maybe others) used on many models.
 

Dancorp

Member (SA)
Apr 13, 2017
127
10
18
Marseille, France
Thanks a lot for your comments guys. Finding a well sized pot with all features looks close to be impossible.
I can expand search results by removing features...
Can someone explain the purpose of the midpoint ?Is this feature mandatory or can i fit a legacy pot with jumpers?
Is the B curve mandatory too ? if i found a A curve pot, will the lever still friendly usable ?
Thanks in advance

Dan
 

Dancorp

Member (SA)
Apr 13, 2017
127
10
18
Marseille, France
You're right, I do not remember where I read 500K.
It is easier to find 50K potentiometer, it's cool.
But I have to find some who have the loudness tap.

Size : 45mm x 8mm with a 15mm shaft.
 
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