JVC 838JW Slider Problems

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Ghettoboom767

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May 6, 2009
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Hi everyone-I just got a nice JVC 838JW and it all works BUT the sound is really faint & on one side.
Now when I first got this I was wiggling the balance slider back & forth quite a bit & the right side started working and sounded really good,then after I touched it again the sound went back to muted.
Then later on after wiggling the balance a bunch more the left side started working and sounded nice.
After I touched the slider again,back to muted on one side.
The volume slider was working fine when the volume was coming through.
The bass & treble sliders don't seem to be working.
I have heard that rebuilding these is really a PITA!
I'm wondering if I could replace the sliders with good ones from another boombox or get a whole other board with these sliders on it.
Any suggestions would be greatly appreciated.
It does all work,lights,cassettte(needs a little aligning but all funtions work)
It is a nice boombox but is sounding very weak with no current getting to those speakers!!
Have a good weekend-GB. :hmmm: :-O :huh: :-)
 

Superduper

Member (SA)
Ghettoboom767 said:
Hi everyone-I just got a nice JVC 838JW and it all works BUT the sound is really faint & on one side.
Now when I first got this I was wiggling the balance slider back & forth quite a bit & the right side started working and sounded really good,then after I touched it again the sound went back to muted.
Then later on after wiggling the balance a bunch more the left side started working and sounded nice.
After I touched the slider again,back to muted on one side.
The volume slider was working fine when the volume was coming through.
The bass & treble sliders don't seem to be working.
I have heard that rebuilding these is really a PITA!
I'm wondering if I could replace the sliders with good ones from another boombox or get a whole other board with these sliders on it.
Any suggestions would be greatly appreciated.
It does all work,lights,cassettte(needs a little aligning but all funtions work)
It is a nice boombox but is sounding very weak with no current getting to those speakers!!
Have a good weekend-GB. :hmmm: :-O :huh: :-)
Jeff. The sliders on the M70 are the same, I'm almost certain. Except the balance control but you can use the parts from an M70 to rebuild that balance control too. The only thing is parting out an M70 to fix an 838 is probably a wash. M70's are going for a very pretty penny right now.

I would not continue fussing with the sliders if I were you. The control is broken because the feelers inside have broken off losing contact. At least 1 piece is still inside the control and you are pushing it around to where if it just happens to fall in the right position and bridges the contacts, you are restoring sound just so long as you don't move it again. If you can't fix the slider, it is possible to modify the board so that the balance is always centered. Who operates the balance offset anyway? Anyhow, by pushing that piece of copper around, you run the risk of grinding down the resistor board which is irreplaceable. The tonal curve is a very unique one and not available from any source that I know of. If you are at wits end, PM me. Maybe I can help.
 

Ghettoboom767

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May 6, 2009
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Thanks guys-I may just do that Norm.I'll PM you later this weekend.
This 838 is really cool & it would be nice to get it working right.
I have 2 M70's but they are really nice!
I wish I had the work station with bright lights,table and a very good small iron to rebuild this-even then I judst don't know if I'm that good! :hmmm:
This boombox will sing again-I'm sure of it.
Have a super weekend-Jeff. :-) :yes:
 

blu_fuz

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I'm going to revive this thread because I am having the same issue of the bass and treble sliders getting no response in the M71 I am fixing up.


They didn't seem to work before I did my restoration and I was hoping to just find a loose connection or something simple... I didn't get that lucky.


The *loudness* switch works fine, all other sliders and switches work as they should.....


I don't think that this situation with both bass and treble not working are because the slides are bad, but maybe because of something on the circuit board went bad?? :huh:


Any help is appreciated. Thanks guys.
 

baddboybill

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Jul 14, 2009
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blu_fuz said:
I'm going to revive this thread because I am having the same issue of the bass and treble sliders getting no response in the M71 I am fixing up.


They didn't seem to work before I did my restoration and I was hoping to just find a loose connection or something simple... I didn't get that lucky.


The *loudness* switch works fine, all other sliders and switches work as they should.....


I don't think that this situation with both bass and treble not working are because the slides are bad, but maybe because of something on the circuit board went bad?? :huh:


Any help is appreciated. Thanks guys.
Joe I'm going to say that the sliders are the problem. Mine gave me problems on my M70 and I was able to trade/ buy for a rebuilt board that Norm had and they are perfect. The problem with some of the boxes is when a slider is at the top of the box it collects lots of dust, dirt and condensation which cause these problems. I would pm Norm and maybe he has a rebuilt board that you could buy from him :thumbsup:
 

blu_fuz

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I just think it is odd that BOTH are totally dead..... that's why I question that it is something else going on.....

My parts box M71 has working bass/treble sliders, but a dead volume slider :thumbsdown: . So I can't just swap those boards out, but maybe I should just to see if the bass/treble issue is still there after the swap :hmmm: . I have to go back into the box anyway so I guess it's worth a shot.
 

baddboybill

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Jul 14, 2009
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blu_fuz said:
I just think it is odd that BOTH are totally dead..... that's why I question that it is something else going on.....

My parts box M71 has working bass/treble sliders, but a dead volume slider :thumbsdown: . So I can't just swap those boards out, but maybe I should just to see if the bass/treble issue is still there after the swap :hmmm: . I have to go back into the box anyway so I guess it's worth a shot.
Well when Norm rebuilds it he does it all and believe me the sound is so amazing and the sliders slide beautifully without any hang ups :thumbsup: well worth it :yes: Norm knows what he is doing and for that he is an awesome member of this forum ;-)
 

blu_fuz

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Oh, I know. Norm has been more than helpful with just about ALL my projects and could tackle the slider issues I am having.

I am trying to send him less of my projects so I can learn through PM or with troubleshooting on my own before shipping it off. I know it's easier and he does great work and it might end up that I send the sliders to him anyway..... I wish I knew more about these things :-/
 

Ghettoboom767

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May 6, 2009
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Good luck with your 71!
I don't have the expertise I'n rebuilding sliders so I was lucky to find
a parts box that had good sliders for my 838.
I wish I knew how! :-O
Maybe Norm can help you,he's smart and technically inclined I'n all
aspects of boomboxes! :thumbsup: :yes:
 

blu_fuz

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Thanks for the link to your slider issues that Norm helped with. I think I am going to attempt looking at my parts box slider for the left volume control and see what I can figure out.

The more I work on this, the better I feel about trying to fix things on my own.

Thanks guys.
 

Ghettoboom767

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May 6, 2009
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Hi Royce! This looks like very hard work!
With me working on the floor and not the best lighting,I'm going
to try to get another slider board or parts box for my 2nd.838.
Man you are good!! :yes: + Norm is a genius!! :superduper:
That's great that you were able to fo this!!
Have a great week! :-)
 

BoomboxLover48

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Dec 3, 2010
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Ghettoboom767 said:
Hi Royce! This looks like very hard work!
With me working on the floor and not the best lighting,I'm going
to try to get another slider board or parts box for my 2nd.838.
Man you are good!! :yes: + Norm is a genius!! :superduper:
That's great that you were able to fo this!!
Have a great week! :-)
HI Jeff, Thanks for the kind words! Yes, Norm is a genius! I would have never did it without his help! Bill gave me the schematics and that was lots of help.

Norm helped me with another M70 recently. With his directions it was easy for me to find the fault and correct it.
It's interesting to see how he walked me through it.
In both cases I enjoyed the work! It was very exciting! :yes: :yes:
viewtopic.php?f=51&t=13113


I have a mint 838 that I got locally from a seller. The radio/tape/line in/phono function selector switch was giving all sort of problems. I had to clean all the switches in the front. From what I remember the switches in the front was connected to the selector stiches through several levers. The selector switch was hidden inside. A good cleanup of swiches cured all the problems I had with sound cutting off from one channel and all.
Royce
 
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