HOME - Back to board
 

FM stereo light on M90

isolator42 - 2008-02-11 04:07

When I tune into an FM stereo station, the FM stereo LED doesn't come on & the sound is mono.
However, if I detune to the point of sound break-up, the stereo light comes on & I can retune properly with the LED on & stereo sound.
If I flip the Meter/Mode switch to check signal strength (which also switches to mono), when I switch back, it's lost the stereo signal again & I have to detune & retune, as above.
Also if I switch off, the next time I switch on it's always in mono & I have to detune & retune, as above.

Is there any pot I can twiddle to sort this out?
Page 9 of the service manual talks about adjusting VR1 on the tuner board (fig 17). Will this sort the problem for me?

It seems Frank (FYJ2972) mentions a common FM stereo decoder problem, where adjusting a pot to 19kHz solved this problem (on an M70 in this post).

Any help is much appreciated Smile

kittmaster - 2008-02-11 07:06

Same theory, look on the FM board:

eddy - 2008-02-11 12:11

Maybe it's better to replace that VR 1

- 2008-02-11 13:17

i have had this prob and done as kittmaster sugested works evry time, easy fix Smile

skippy1969 - 2008-02-11 13:42

Yup,I learned Kitts method too,it has worked everytime for me. Nod Yes

isolator42 - 2008-02-11 15:21

Thanks gutys - so it's out with the tools. I've been looking for an excuse to take it apart again. Now to find the time... Smile

kittmaster - 2008-02-11 15:41

Make sure you also put some tuner cleaner on the pot while you turn it to clean off carbon tracking and indenting.

isolator42 - 2008-02-12 02:35

er... what's tuner cleaner? Smile

kittmaster - 2008-02-12 06:10

Everyone knows it as deoxit, but this has been around longer and does the same job

http://www.radioshack.com/product/index.jsp?productId=2...er&parentPage=search

isolator42 - 2008-02-12 10:27

quote:
deoxit

ah, got it - it's a contact cleaner. Yup, I've got some of that. The trick is to be sparing & not drown everything in it...

...thanks Chris, for the accurate & helpful advice.
The search for the time to do the job continues... Smile

eddy - 2008-02-16 09:11

Every electronics store has them