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I have recently installed a stereo decoder in my Beomaster 900M.
It fits into the socket correctly but the problem is that the stereo signal is very intermittent.
Both the stereo light flashes and it switches from mono to stereo as it drifts in and out of stereo on FM. The signal is not the problem as it is picking up a strong enough signal but it almost seems like a loose connection. I have reconnected the decoder into the socket without success.
Any ideas?
Anyone had issues with the stereo decoder before?
Ben
It could be the decoder in need of alignment - depending on the type it is not too uncommon.
Are you sure, that both IF-stages are working correctly ?
Martin
That model is not the worst when it comes to the need for alignment.
Alignment is calibration of the tuned circuits (adjusting of the coils) on the module as mentioned in the servicemanual.
Martin
My memory is a bit hazy on this issue,but wasn't there a filter network that had to be removed when retro-fitting the decoder?
Did you have any fitting notes with your kit.
I'll go through my "archive" of Beonotes.
Was your kit "new old stock" and as such previously unused?
If the coil cores are not sealed,the "phantom twiddler"may have visited at some stage,and you may indeed have to realign the decoder.
Regards,
Nick
There is a de-emphasis plug, but it will have to be removed because the MPX module plugs into the same socket.
Both cannot be plugged in at the same time.
The coil cores are locked, that's the yellow stuff you can see in the photo. Looks undisturbed as far as I can tell, but they could
have been fiddled with from the other side.
Most sensitivity problems in these receivers are caused by bad IF-transistors.
Martin
Also the stereo indicator light is switched by a dedicated resonator circuit that needs to be in tune as well. So the receiver might actually be playing in stereo even though the lamp goes on and off, or doesn't light at all. Of course, with most music material you would hear the difference.
Martin is right, the plug has to be removed to plug the stereo decoder in.
I confirm that I have got stereo playback on FM (sometimes!) and as you say Mika you can tell the difference.
I will have a look at the IF transistors and let you know if this cures it.
Thanks all
Ben
I have just acquired a Decoder which has just been repaired, as the volume level was down on one channel. Audio wise it now sounds fine, but the green STEREO indicator does not illuminate.(it lights up OK on Tape and Phone).
Can anyone offer any advice please?
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