Question about the M70 bass/treble sliders

Presto

New Member
Mar 14, 2021
10
2
3
CT
IF you are in the USA, I offer these NOS Alps sliders for $13.95 plus S/H. 3+ and I can include shipping. They are 50KWX2. I would recommend simply using the internal bits to rebuild your existing sliders to preserve the original characteristics. Physically, they are the same size as the original Alps sliders in the JVC M70 and 838. The knob shaft might need modification to fit the knobs depending on whether it is the M70 or RC-838. Look at photos and decide for yourselves.

View attachment 52739


View attachment 52740
So you use the original pcb and replace the rest? And possibly tweak the post
 

Superduper

Member (SA)
The NOS sliders are identical internally (except for the resistance characteristics) because they are the exact same brand and series from the same manufacturer that are in the JVC boomboxes (M70-series, RC-M838-except volume). If you harvest and cannibalize the internal sliders, then you reuse the rest. I've been offering slider board rebuild services for over a decade and this is how I do it. If you rebuild it with new silicone grease, this results in a slider that feels like brand new, and operates like new and sounds better than ever. On the other hand, the center slide block (with the feelers attached) is a drop in replacement for the old too so you can install it without doing anything except removing it and replacing it. But the knob shaft is a little longer so it will have to be trimmed (not sure about the width, I didn't do it that way). If you don't care about the resistor board value being different, you can even simply replace the slider without doing anything like Kololei did. As for the internal feelers, there are 2 per slider and they will fit on any of the 6 sliders on the M70. The stereo pots (bass/treble) will use both. The mono pots (record-level, volume) will use 1. Keep in mind that there are left and right feelers and they are not interchangeable. One last detail, the bass and treble sliders have a center detent that is handled by a tiny spring and ball bearing on the center nylon block. Be careful you don't lose those. These new ones don't have that center detent. Functionally, its not required but I would keep those or transfer to the new slider if you want to retain the feel of a center detent. Oh, one last note, these have the center taps. The original Bass and Treble sliders don't use that feature so those pins can safely be trimmed off -- you won't need them, but this is only if you are using the resistor board. If you are just cannibalizing the feelers to rebuild yours, these don't matter. The volume board do however use the center tap, but I don't have any mono sliders, just stereo ones. Perhaps someone interested in doing some microsurgery can grind down the stereo boards so they fit onto a mono body. For me, it seems much easier to just rebuild the originals.
 
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Presto

New Member
Mar 14, 2021
10
2
3
CT
Superduper

Just installed the board and all I can say is WOW!!!
What great work the sound hasn't been this good since new!
Worth every penny... you are the MAN! Your attention to detail is not lost on me and your expert work has renewed my faith in mankind!

I would recommend your service to anyone. I should have shipped the whole boombox to begin with!
 
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Just MV

Member (SA)
Jul 10, 2022
51
41
18
France
Bonjour

parmi ma collection de boomboxes, j’ai une RC-M70 qui contrôle le volume de la glissière avec la piste endommagée. J’ai tout essayé. Y a-t-il des diapositives identiques où je dois faire les pistes avec de la peinture spéciale
ALPS VOLUME JVC RC M 70.jpg
 

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Just MV

Member (SA)
Jul 10, 2022
51
41
18
France
Hi all, my new purchased M70 have problem with the bass and treble slider. They travel up and down smoothly but make no effect on the sound. I read few topics here and assuming that the problem is broken slider pots (missing/loosen feelers).

I look up on internet and found this potentiometer that looks very similar to the original pots. It has right dimension, looks almost the same from outside, and it even has mid point tap. Before I order them, I have few question need your guys help.

View attachment 52577View attachment 52578View attachment 52579

1. Le potentiomètre basse / aigu sur le M70 écrit A100k, alors que celui-ci est B100K, fera-t-il beaucoup de différence dans le son? En supposant que le nouveau puisse bien s’adapter au tableau.
2. En ce qui concerne la réponse à la question ci-dessus, me suggéreriez-vous de remplacer (échanger) l’ensemble du pot, ou est-il préférable de ne profiter que de l’assemblage mobile (le palpeur et la poignée). Toujours en supposant que la partie intérieure est interchangeable.
3. Les pots de basses/aigus sur M70 et RC-838 sont-ils les mêmes, interchangeables ?

Beaucoup apprécié toute aide. Merci.
[/CITATION]

J’ai le même problème sur mon JVC RCM70...

quelle est la référence exacte des potentiomètres basses/aigus s’il vous plaît
 

Just MV

Member (SA)
Jul 10, 2022
51
41
18
France
J’ai réparé avec succès les traces brisées m70 avec de la peinture conductrice.
Lorsque vous le faites, il est préférable de faire la même action à gauche et à droite afin de créer le même niveau de résistance.
La peinture conductrice est appliquée en couches après que chaque couche a séché, j’ai constaté qu’environ 3 à 4 couches suffisaient pour rétablir la continuité mais j’irais en toute sécurité avec 5.
Dans mon cas, la déconnexion était entre le point final de la trace et l’épingle, et j’ai vu cela un certain nombre de fois comme étant le point de détérioration habituel. Vous pouvez tester cela avec votre test de continuité dmm.
[/CITATION]

Bonjour
J’ai le même problème sur mon JVC RC M 70...
quelle est la référence exacte de la peinture utilisée s’il vous plaît, les deux glissières de volume sont défectueuses..