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Beocenter 9500 no sound at low volumes

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ferret30
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ferret30 posted on Wed, Sep 8 2021 12:15 AM

I recently bought a really nice Beocenter 9500 with a pair of mint brushed aluminum CX100s. I was really only trying to get the speakers but the seller thought it would be hard to sell the 9500 separately so I made a deal for the set.

I brought along a cassette and CD to test on it, and it all worked fine. Buttons, remote, doors, etc. I spent the first several hours with it removing the loose glass, cleaning the adhesive gunk, then reinstalling the glass.

When I finally connected to speakers (first time at home) I noticed that whatever source I set it to, there is no sound until I turn it the volume up at least half way, then the speakers kind of cut in. At that point it will work at lower volumes again. This is repeatable -- if I turn it off and on again it does the same thing more or less. It sounds ok after the speakers cut in.

When I overhauled a faulty Sansui AU-717 recently it had almost the same issue. It turned out to be the startup delay/protection relay, and replacing it cleared it up. I'm wondering if it could be the same issue here? It still seems odd to me that dirty relay contacts will 'form' a connection by turning up the volume, but that was my experience.

Does it seem like it could actually be the relay in this case? Or would it maybe be the volume control IC? I am really new to working on 'modern' equipment like this -- I've mostly only fixed/overhauled things with volume pots, no remotes, manual input selectors, etc.

BTW I did try to search for existing threads on this but my search efforts weren't successful. If this has been covered a lot already I apologize in advance.

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ferret30
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Ok, I did some more testing and I'm pretty sure it's the relay so I ordered one (G2R-2-DC6). I skimmed the manual and found the advice for accessing this particular PCB. I have lifted it and tilted the unit out (with the heatsink attached). Any advice for accessing the back of the PCB? It looks like there are some plastic standoff clips holding it all together. Also, there are ribbons from this PCB to some components on the heat sink. I'm guessing the sink can be folded away once I get the clips free. Is this basically it?

One other thing -- the CD player works fine but doesn't read some lightly scratched discs. I am not set up to do the sort of calibration work mentioned in the manual, so I am hesitant to pull the unit to recap the driver board. I'm concerned that if I do maneuver it to access the PCB underneath that something will get out of alignment and then it will have to get sent somewhere for a tune up. What do you think?

I am not planning to hold on to this 9500 long, and would just like to get it sounding good and working well (e.g. replace the relay) for the next owner.

Menahem Yachad
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Do not touch any calibration.

That's NOT the problem.

There are some capacitors which are known troublemakers and need to be replaced.

On the small PCB attached underneath the actual laser mechanism, C2103 and also the same types on the Main CD Decoder PCB

Once you have removed those 2 PCB's, advise, and I'll be happy to help you.

 

ferret30
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ferret30 replied on Wed, Sep 15 2021 12:00 AM

Thanks for the offer to help. I think my post wasn't clear. I wasn't planning to do any calibration on the laser/pickup. My concern was that moving the mechanism out of the way to access the PCB might cause it to get out of alignment.

Since I posted I ended up cleaning the lens with 99.9% IPA on a cotton swab. After I let it dry I grabbed a stack of 20 or so random CDs from the attic (it's all been ripped to a NAS so I never play CDs anymore) and they all read fine, old scratched and new clean discs. Since I'm not planning to keep the 9500 I'm tempted to just take the conservative route and sell it on with the disclosure that it still contains original parts (as far as I know -- I don't know the service history).

Thanks again for the offer to help. I may end up doing the project if I get bored, but then again I've got 2x Beomaster 4500s and 2x Beogram CDs that I plan on keeping that could use servicing (and the tape holding the glass in needs replacing).

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