You ever drill a hole with a needle?

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blu_fuz

blu_fuz

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So far, I was only able to do the work and make sure the feelers line up on the pot board correctly. I do believe it is going to be 100% functional.


Matter of fact, this is a COMMON problem for JVC M90 potentiometers. The melted plastic buttons that hold the feelers on eventually break off. Could be an age, use, or abuse issue.

We have been discussing behind the scenes that these M90 pots should be opened up now and reinforced with a small screw in the center hole of each feeler plate. Probably add a dab of epoxy to the existing plastic buttons and these should last a lifetime.

Some of us might already have a damaged pot and not know it.


Mine was acting strange.

From 0 to about 3/8 volume mine sounded OK but a little flat like if the loudness was off.
Then from 3/8 to about 1/2 volume there was scratchy left speaker only and right speaker didn't work at all unless you fiddled with the knob shaft.
Then from 1/2 volume and up it was nice and clear out both channels and as if the loudness was working again.

The knob rotation also didn't have the soft tension on it like my other M90 volume knob had.
 
Lasonic TRC-920

Lasonic TRC-920

Moderator
So basically it was worn out in the "Typical Use" section of the knob position. Makes sense.

This is important information for ALL M90 owners! (i'm not one :sad: )
 
JustCruisin

JustCruisin

Member (SA)
I'm reaching far into my memory banks on this...But, wasnt the word on the streets that M90 shares its volume pots with Panasonic 5050..? :hmmm:
 
blu_fuz

blu_fuz

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Close

You lose balance control, loudness, and the D shaft is rotated different so the M90 knob will never point to the correct volume setting. But, a panny 5050 pot is better than nothing!
 
blu_fuz

blu_fuz

Well-Known Member
Staff member
I guess I should have posted this in the JVC M90 section.


I dabbed a little white lithium grease on to the base of the shaft where it enters the metal casing. That is to restore the soft turn motion that it originally felt like. Got it closed back up. The motion feels almost as good as my othe M90.


Hopefully it all works after the box is back together.

image.jpgimage.jpg
 
blu_fuz

blu_fuz

Well-Known Member
Staff member
The repair worked PERFECT. 100% restored sound and fixed to last. Very happy right now :w00t: :clap: :rock: :thumbsup:
 
caution

caution

Member (SA)
I own this pot now. I would advise against a screw. I used JB PlasticWeld and it worked great. It's harder than regular JB. Pics: https://boomboxery.com/forum/index.php/topic/18208-for-those-that-have-m90-and-maybe-on-there-wishlist/?p=335000

The original rivets are too short to match with a screw, and there's no extra clearance. The missing carbon is where the screw moved over the track.
33680506601_d0915466e4_b.jpg
 
BoomboxLover48

BoomboxLover48

Boomus Fidelis
caution

caution

Member (SA)
That's not a bad idea. Maybe I can cover the spots with conductive paint. I'll never make the same recipe to recoat those spots to make them exactly as they used to be, but most of it is at the end of the scale so it may not be noticeable.
 
Newclairtone7980

Newclairtone7980

Member (SA)
hi I'm new but what I was trying to say that the jb glue would work the best I'm going to do that to my pot your right the screw would do damage to it
 
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