Beogram 5005 right channel output lower than left

18 replies
Hi

I bought a Beosystem 5000 including Beogram 5005 record player. When playing the records I noticed that the right channel was consistently at lower output than the left. With Sennheiser HD-25 headphones it's noticeable, but even clearer it can be seen in this screen capture:
http://img72.imageshack.us/img72/535/picture1hm3.png

I thought it was the MMC4 needing replacement, so I bought the Soundsmith SMMC4. New stylus improved the sound by a large margin but the channel output inbalance did not disappear.

Swapping the RCA cable did not remove the problem, and reversing channels with RCA adapters had the lower output switch to the left channel of course. Can anyone give me some ideas what to check next? I really want to get rid of this problem, rather than having to  invest in a mixer with settings fine enough to compensate for the lower output on the right channel.

Kind regards,

Vilhelm
 

You seem to have checked everything else so check the internal resistance of the mute switch in the deck.

Pardon my ignorance but how do I do that? I have the service manual, but did not find this in it.

http://forum.beoworld.org/forums/thread/39770.aspx <-- This topic the poster has a similar problem and it turned out to be "the mute switch" as you wrote. I wonder, how do I correct it?

I don't think you can clean the contacts since it is a sealed microswitch. Ask your dealer if the part is still available. Pt Number 7400293

Very kind of you, thank you! Does anyone have any ideas where I can buy the parts online? I am pretty sure my dealer does not order them because B&O center in Helsinki no longer supports vinyl players :-(

Vilhelm 

I too have the same problem - symptoms the same, one channel very low then when the arm lifts, momentarily, there is the full level of sound.

Is this muting switch available anywhere. Part number 7400293

Given that I don't have a servicing agent in this state, can anyone recommend a dealer, in any country, who might be prepared to order the part.

Or maybe Martin or Chris has one ? Do they come in any of the other tangential turntables ?

Tasmania, Australia is a long way from anywhere B & O.

Thanks, I look forward to hearing from you. Merry Xmas to you all.  

The same muting switch is used in all the "lightweight" tangentials from the BG3000 onwards.

Surely the Aussie dealers will supply this part by post??

Couldn't you just bypass (i.e cut off) the switch until you get a replacement? Most other turntables in the world have never heard of a muting switch, and they still won't destroy the loudspeakers with a Bang, so to speak :-) Not quite as sophisticated, but at least the levels would be right...

-mika

I'd be happy to bypass the switch temporarily if I knew the location and the method of bypass.

I'm an amateur at this, hence the requirement for the information. As far as dealers in Australia go, there are only a few and there is a reluctance to sell a part to an amateur not connected with the dealer or service network - very protective as a rule.

Thanks for the replies

I made an attempt to " bypass " the switch, inasmuch as I have tried the unit with the switch  fully depressed.

No joy - there was no sound from either channel.

With the switch in the out position, the right channel working well, the left barely audible, back where I was.

When the arm lowers to the surface, momentarily the left channel will work, same as when lifting the arm, again only momentarily.

When checking the switch according to the service manual, on page 5-4 I've no idea what the heck I'm doing really. I turn the arm until the muting switch just opens...............than whay ? The manual doesn't tell me what I'm looking for or checking.

The arm has to move the switch perhaps .7mm until a reading goes from OL to 760 odd ohms, then to .3 ohms or less.

Does this point to the switch being faulty ? 

How is the bypass of the switch effected ? Which pins are joined ? 

I am not totally confident of my soldering capabilities to take the muting unit right out of the loop and wondering too what effect this is likely to have. In the toolbox is some thin wire similar to that from the cartridge - would this be best ? Should the duff switch be removed for this to be effective or can it be left in place ? Is the switch actually faulty ?

The service notes neglect to mention the resistance required with the muting switch. The notes read as if this vital piece of information is missing. ( page 5.4 ) Or is the function of this test to determine whether the switch is working or not ?

Happy to speak to anyone on the telephone, in any country, at my expense, in an effort to complete my task. 

Thanks in advancel. 

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