Need help ! National RX-CW50f

[Saqib Sami]

Hi, I recently bought a boombox National RX-cw50f made in Japan.
How to clean controls i.e volume, fine tuning potentiometer(s), equalizer controls? board is also dirty.
Also some other problems I noticed are
Tape2 pinch roller and head is locked in playing position, fm tuner is not working and one speaker is showing impedance of 90+ ohms.

Before posting this, searched on this forum for this model but could not find enough information.

 

[goodman]

You must open boombox to fix this problems. You need contact spray to clean all potentiometers.
To fix cassette decks you must reassemble decks and clean everything carefully, replacing belts etc...

 

[Saqib Sami]

Boombox was opened before posting here.
contact cleaner spray name?
Yes both cassette decks need new belts.
How to re assemble cassette decks?

It is my first experience with a boombox so there are lot of questions to ask. Thanks for help.
I have experience of soldering, desoldering, using multimeter and replacing IC's like tea2025b,tda2030a..

 

[goodman]

there is a lot of dirt and dust here.
the circuit boards, all switches and potentiometers must be carefully cleaned.
earplugs soaked in pure alcohol or some deodorant may be used.
if deck 1 works well, look carefully at deck 2 to determine the reason for its blockage.
you will need to disassemble it carefully and clean it. take pictures to know how to reassemble it.

 

[Saqib Sami]

Desoldered both motors of Tape deck 1,2 .
Each deck has probably two belts one thick belt and one thin belt. thin belt is into pieces and thick belt is cracked . Need to replace these both belts in total 4 belts.
Also tape2 was stuck in playing position due to thick belt was not able to provide enough support to get mechanism back in position.
after taking off belts now mechanism is free and back in place.

 

[Saqib Sami]

Dirt and dust is due to its age 30+ years old.
I want to remove all the dirt and dust stuck on motherboard, how can it be done without damaging components or board itself?
I have seen restoration videos on youtube they pressure wash the whole system i.e cassette decks, circuits and plastic cases. is it safe?

 

[Saqib Sami]

Deck 1,2 Pictures.

 

[hopey]

Looks like you need access between the mech's and PCB to change belts. Doesn't look easy.

 

[goodman]

I want to remove all the dirt and dust stuck on motherboard, how can it be done without damaging components or board itself?
I have seen restoration videos on youtube they pressure wash the whole system i.e cassette decks, circuits and plastic cases. is it safe?

Don't clean with water. Cotton buds in pure alcohol or some deodorant may be used.
Look this video: cleaning

Desoldered both motors of Tape deck 1,2 .
Each deck has probably two belts one thick belt and one thin belt. thin belt is into pieces and thick belt is cracked .
Need to replace these both belts in total 4 belts.

Easy way is to buy some kits from ebay:
flat belts kit
square belts kit