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We recently acquired a Beogram 4000 turntable (to complement our Beomaster 4000 and original speakers), which has now been serviced and a new stylus fitted. The turntable works perfectly; the sound quality is excellent. But there is a loud amplified hum evident. The phono din is wired correctly. Can anyone advise on what might be wrong? I have little technical knowledge/expertise. Is there an easy solution or does the hum point to the need for expert testing and possible component replacement? I notice that neither unit is earthed or (seemingly) is able to be earthed. So presumably that is not the problem.
Thanks.
Robin
You have an earth problem! They should both be at the same ground potential or you will get the very hum that you are talking about.
This is normally achieved through the metal casing on the DIN plug and the metal shield on the DIN socket.
If your Beogram has been modified with phono plugs then you will need to run a supplementary wire from the chassis of the deck to the chassis of the Beomaster or convert the deck back to it's original spec by fitting a proper DIN plug to the output cable.
Regards Graham
OK: thanks very much. I understand the problem. In fact the lead did have phono plugs; the repairer has simply fitted a din plug to that (3 core) lead (so no earthing). I guess the best solution is to replace the lead with a din lead (rather than add a supplementary wire), yes?
Thanks for your trouble.
As far as I am aware, all Beogram 4000's were fitted with a shielded lead which terminated in a 5 pin DIN plug.
At some time in it's life, you Beogram has been modified with phono plugs.