JVC M70 Left speaker very low:

[label321]

Hello people,


Was playing records last night works great for 1 hour,

But after 1 houre i noticed that left speaker/channel was very weak.

Radio seems to be oké.

i im not an electronic wizz so hopefully its a simple issue.

Let me know please.


Regards Justin.

 

[BoomboxLover48]

Hello people,


Was playing records last night works great for 1 hour,

But after 1 houre i noticed that left speaker/channel was very weak.

Radio seems to be oké.

i im not an electronic wizz so hopefully its a simple issue.

Let me know please.


Regards Justin.

This is a very common problem with boxes having slide switches. Probably the volume control slide switch needs service.
For the time being try to spray a little Deoxit D5 Faderlube in the left slide switch of volume control and move it back and forth to see if that helps.
If the carbon resistance strip is broken you might have to fix that issue.

 

[label321]

This is a very common problem with boxes having slide switches. Probably the volume control slide switch needs service.
For the time being try to spray a little Deoxit D5 Faderlube in the left slide switch of volume control and move it back and forth to see if that helps.
If the carbon resistance strip is broken you might have to fix that issue.

Witch conductive paint i read here.

And is there a way to replace those sliders?

If so a link please.

Maybe Aliexpress or some tech website i live in Europe.


Regards Justin.

 

[BoomboxLover48]

JVC M70

I have a JVC M70 that got one channel is very weak and the other not strong enough either. When I increase the volume on the channel that is weak it got no base and teh volume slightly icreases to half of its way and then remains at the same level. Is this an issue with components in the the...

boomboxery.com

Hope this helps...
I got help from Superduper and badboybill for this project when I was new here...
~Royce

 

[BoomboxLover48]

Search for silver conductive paints, some pens also should work
www.aliexpress.us/item/3256803489507843.html?

 

[label321]

Is that rec slider important ?

If was thinking to switch that oone with a volume slider.

Let me know.

 

[label321]

Update:

The left volume slider seems to be defect.

I was testing the radio same problem as line in.

Maybe you can use rec slider and chane it for volume slider ?

Or is it that carbon tracks that are defect and i need the conductive paint to repair that issue ?

Let me know.


Regards Justin.

 

[BoomboxLover48]

I doubt you can replace the volume slider with the record slider. I don't think so. Check the resistance of the carbon tracks and it should read 50KOhms. If there is a break it will immediately show. then you can trace on the carbon track with multimeter probe gently and find the area where the crack is.
The best option is to get it professionally serviced replacing any bad components.
Superduper used to professionally service it all and make it work like new. In that case you have to disconnect that tone board and ship it to him.
I would ask him if he got time for this job. You will be pleasantly surprised with his flawless work. He is the Master Tech here. A genius!

 

[label321]

I doubt you can replace the volume slider with the record slider. I don't think so. Check the resistance of the carbon tracks and it should read 50KOhms. If there is a break it will immediately show. then you can trace on the carbon track with multimeter probe gently and find the area where the crack is.
The best option is to get it professionally serviced replacing any bad components.
Superduper used to professionally service it all and make it work like new. In that case you have to disconnect that tone board and ship it to him.
I would ask him if he got time for this job. You will be pleasantly surprised with his flawless work. He is the Master Tech here. A genius!
View attachment 56188
View attachment 56187

So i dont know if he can help me with this.

I live in the netherlands europe.

What are the options desolder the slider paint it with the conductive painbts en solder it back in ?

Or replace the whole thing with a new on all of them if possible.

Where can you buy these sliders new ?

i just bought this boombox for 275,- euro on ebay.

 

[BoomboxLover48]

Once you find the break on the carbon strip you can use conductive paint right at the break, don't spread the length of the fixing area on the carbon disc. If you do so that it will decease the resistance value to some extend. You can fix it that way. In that case you have to remove the slider switch from the tone board. Then open it up carefully and do the work.

Our members here will chime in and give better advise.
I am no expert here.

 

[hopey]

You can use the the internal contacts from the rec sliders to fix the volume sliders. Pull it down and should be able to make it work. You can still use the rec function at auto level control.

 

[label321]

You can use the the internal contacts from the rec sliders to fix the volume sliders. Pull it down and should be able to make it work. You can still use the rec function at auto level control.

Do you mean the fingers on the inside of the slider ?

Or the whole track and fingers ?

Or is it possible tho replace the rec slider for the volume slide.

switch the 2 i mean.

 

[hopey]

I can't remember if they are transposable like on the Sharp 9090. Inside the slide the contacts are mounted on a plastic block which is identical in both rec and vol pots. This means you have standard parts that can be swapped. Once you open the slider it will all make sense if you get that far.

fisher used similar alps sliders as well

 

[label321]

I can't remember if they are transposable like on the Sharp 9090. Inside the slide the contacts are mounted on a plastic block which is identical in both rec and vol pots. This means you have standard parts that can be swapped. Once you open the slider it will all make sense if you get that far.

fisher used similar alps sliders as well

Thanks!

Hopefully i can fix those volume sliders this way.

I dont know but if i use the rec slider nothing happends i dont hear a difrence in sound.

I can maybe find a tech guy and tell him that this is a possible way to repair them.

I dont know yet.

Thanks again!


Regards Justin.

 

[BoomboxLover48]

Here is some very valuable information regarding M70 sliders from @Superduper
Go to #15

Question about the M70 bass/treble sliders

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...

boomboxery.com

~Royce

 

[Superduper]

The record and volume slider resistor boards are incompatible. The resistor values are too different: 50kΩ vs 500kΩ and the tonal curves are different too.

If you are hearing any sound coming from the L speaker, then the resistor board is most likely not broken or fractured. A more probably cause is the small internal feelers are loose or detached or there's dust and debris accumulated inside the sliders. You can try faderlube from Caig, flip board upside down while flushing the sliders and see if it helps. Turning the board upside down as you do this allows the chemical to drain out. Obviously this is much easier if the board is removed from the boombox. Do not overwork it and if it does not improve, the feelers might have become detached, in which case, stop and fix it. Continued movement might grind the loose feeler into the resistor track and degrade it.

If the feelers have become detached, then you'll have to disassemble them to repair. This is a rather delicate task and once you begin, you may have to repair the volume, bass and treble sliders too, as the audio signal goes through all 3 sliders before it makes it to the amplifier.

I still repair these, but only if they are virgin unmolested sliders, as I do not repair other people's work. Generally speaking, you can only open these up once or twice before the holding tabs the secure the metal case to the resistor board breaks off, so it's important that they be done right the first time. There are limitations to what can be repaired and customer pays all shipping charges if international.

 

[label321]

Hello Superduper,

Wat wil it cost to send the toneboard and repair in total ?

I can do a banktransfer if you give me a screenshot of your bank number.

If you received the money then i can send you the board.

I live in the netherlands.

Let me know.

The record and volume slider resistor boards are incompatible. The resistor values are too different: 50kΩ vs 500kΩ and the tonal curves are different too.

If you are hearing any sound coming from the L speaker, then the resistor board is most likely not broken or fractured. A more probably cause is the small internal feelers are loose or detached or there's dust and debris accumulated inside the sliders. You can try faderlube from Caig, flip board upside down while flushing the sliders and see if it helps. Turning the board upside down as you do this allows the chemical to drain out. Obviously this is much easier if the board is removed from the boombox. Do not overwork it and if it does not improve, the feelers might have become detached, in which case, stop and fix it. Continued movement might grind the loose feeler into the resistor track and degrade it.

If the feelers have become detached, then you'll have to disassemble them to repair. This is a rather delicate task and once you begin, you may have to repair the volume, bass and treble sliders too, as the audio signal goes through all 3 sliders before it makes it to the amplifier.

I still repair these, but only if they are virgin unmolested sliders, as I do not repair other people's work. Generally speaking, you can only open these up once or twice before the holding tabs the secure the metal case to the resistor board breaks off, so it's important that they be done right the first time. There are limitations to what can be repaired and customer pays all shipping charges if international.

to

 

[label321]

So it seems that the volume works but the left speaker is not bounce link the right speaker.

And stereo jack only the right speaker works with headphones cleaning it doesnt work.

I dont know what it is.

Volume knob works you see the vu meter go left or right when you slide it.

Any ideas what is could be ?

 

[STEREONOVA]

Hello people,


Was playing records last night works great for 1 hour,

But after 1 houre i noticed that left speaker/channel was very weak.

Radio seems to be oké.

i im not an electronic wizz so hopefully its a simple issue.

Let me know please.


Regards Justin.

It's good to get some contact cleaner

 

[label321]

It's good to get some contacts

Contacts ?