The Workbench

Re: Line out hum on Beomaster 5000

ZaphodB — Thu, 03 Sep 2009 05:43:27 GMT

I have 2 pairs of MFBs one pair are 532s (the originals) and the other pair are 544s (updated 532 as far as I can tell) if you have the service manuals that would be great as one of the 544s has a fault (will not turn on suspect relay)

Stewart

Re: Line out hum on Beomaster 5000

ZaphodB — Thu, 03 Sep 2009 05:40:49 GMT

I think this will be it, as I have cheated and used a wire from the earth point to the outer case of both Phono plugs and this has cleared the fault, which would indicate to me that the outer part of the pre-outs are floating.

Stewart

Re: Line out hum on Beomaster 5000

Dillen — Thu, 27 Aug 2009 17:09:21 GMT

In the mean time, you can check the solder joints around the line out plugs.
The whole bottom part of the connector bay is often found loaded with poor solder joints, also
where the vertical board holding the DIN sockets is soldered in.
Sometimes, the PCB tracks can even lift off the board.

Dismount from mains, flip over the Beomaster upside down and remove the bottom plate to inspect the area.
Worth checking the driver transistor joints too while in there.

Martin

Re: Line out hum on Beomaster 5000

solderon29 — Thu, 27 Aug 2009 16:58:23 GMT

I remember that those old MFB (Motional Feed Back) speakers were rather good!

As the Philips speakers are active,you may be getting a ground return loop.Are they earthed?Is the Beomaster grounded say,via a turntable also?

I think I've got a service manual for that speaker,I'll dig it out and check the spec.

Regards,

Nick

Line out hum on Beomaster 5000

ZaphodB — Wed, 19 Aug 2009 17:14:52 GMT

Hi, I have a Beomaster 5000 which I have been trying to use with my Old phillips MFB speakers. But I am getting a nasty hum in the line out signal, this is also present in the tape out. It sounds like somthing is not earthed. The correct signal is there but has an awfull hum on top.

I should add the hum is not there when I use nomal speakers attached to the outups on the Beomaster. And the hum is not there on the phillips when conected to my old HK's pre outs and its not a 50Hz hum!

Stewart