RC-M70JW meter issue

[Mustang06]

Hello friends I recently received jvc RC-M70JW and needed some work tape deck etc but the right side vu meter was not working.It would move if you put it in tape record mode but not work right still or in radio mode to listen to the radio.the left vu meter works fine.jow I figured it was just stuck easy fix but no ...I tested it with multimeter and both responded correctly without getting stuck. The sound comes in nice and clear both speakers plus I took all sliders apart fixed them and clean and greased them and smooth as can be but still after all that no right side vu meter action? I cleaned all wire connections to all boards all switches clean and still nothing .any ideas would help.like I said sound comes out nice clean both speakers but it seems like it's bi passing the right vu meter and just not working.

 

[BoomboxLover48]

Clean that long record switch with Deoxit FadeLube5. That will help!

 

[Mustang06]

Clean that long record switch with Deoxit FadeLube5. That will help!

Yes did all that when had the board out soaked them good and worked them back and forth many times still not sure why the meter isn't getting a signal I tested.its gotta be on board not letting signal get through.

 

[Superduper]

That switch is very hard to clean. Just spraying that bar mostly just washes the outside as it’s well shielded. You have to stand it up on end, inject at the upper end and work it letting the solvent drip down, repeat, repeat many times more, etc.

 

[Mustang06]

So far I've found that pushing on back part of the main circuit board I was getting the meter to respond..so I figured it was a cold solder joint. Nope...so I would heat the back board with hair dryer and it also worked for a bit so that might mean there's a caponent going bad the board doesn't looked cracked so either a bad capacitor might be going

 

[Superduper]

Did you reflow all the joints already or did you just examine it with a glass? Cold joints aren't always visible to the naked eye. You may want to obtain a service manual and determine which joints and traces are associated with the meter circuit, then reflow all of those joints. Heating the back of the board could cause the board to expand just enough to bridge any open circuits, behaving as if you pushed on the board. Or it could be a component changes characteristics and begins working again when heated. However, I suspect it is far more likely that you have broken joints or traces.

 

[docs]

arent there some inboard resistors on the m70, can't remember but when i had this issue i think it was something embedded in the board

 

[Mustang06]

Did you reflow all the joints already or did you just examine it with a glass? Cold joints aren't always visible to the naked eye. You may want to obtain a service manual and determine which joints and traces are associated with the meter circuit, then reflow all of those joints. Heating the back of the board could cause the board to expand just enough to bridge any open circuits, behaving as if you pushed on the board. Or it could be a component changes characteristics and begins working again when heated. However, I suspect it is far more likely that you have broken joints or traces.

That's what I'm thinking it's a tricky one I did solder quite a bit om back where I was pushing on the board and all around where it was trying to work.when I heated the board I watched the meter when it would jump and start working so I kinda figured it gotta be right in that area ...so I solder some more and still nothing so something on back where all the components are might be bad and heat just activate them just enough too work for a bit I'm thinking ..as for Crack on a trace that also could be I will have too re take the board out and fully inspect it cause the meter does work but only when certain pressure or heat is applied in certain area on board.

 

[Mustang06]

arent there some inboard resistors on the m70, can't remember but when i had this issue i think it was something embedded in the board

I think there is... I read or heard someone on another boombox problem with meters not working about resistors that prob could also exist.