I have a Beogram 4002 type 5523 US version that I have owned since around 1978.  I've always had to deal with a hum noise that I thought was coming from my pre-amp.  The hum sound, I estimate, is about 60hz and is present in both channels.

I've tried different things to try to isolate it.  Since it makes the noise at idle, with the solenoid to the cartridge open, I don't think it is coming from the cartridge.  After changing preamps I also tried a shorter and heavier guage ground wire.

This model has RCA cables, instead of the DIN, that are of poor quality.  The wire conductor is small and the connectors are low quality and starting to oxidize.

Is this a common problem with these models?  I really want to clean this up so I can make better digital copies of my vinyl.

Any ideas on what to try next?

As you can tell this is my first post.  The one thing that I am a little sensitive about is when people characterize equipment of this era as old.  I bought my 4002 when I was 20.  OK, I guess I am old too, but perhaps people could use terms like vintage or seasoned in the future and by all means avoid the word antique.

Almost certainly due to a bad replacement job when the DIN cable was replaced. I suggest finding a donor model -- a non-working 4002 -- and getting the original DIN cable from that. Alternatively one of the members on the board may have a spare cable. If I recall correctly this cable actually "plugs in" to one of the daughterboards, so it is not a very complicated replacement. This will ensure both grounds are made and the hum should disappear.

Have you got a separate earth as well as the two RCA plugs? If not, get a piece of wire (almost any wire will do!) and jam in between the metal part of the lid and the back of the Beogram and attach this to the earth on your amplifier. You should find the hum goes. There is another earth in the Beogram that grounds the chassis and this will be missing in yours. That is the cause of the hum. Lovely deck, the 4002. I use a 4000 and a 4004 most days. Much better made than almost any deck you will buy today and pretty good sound. I would suggest changing the RCA lead if it is oxidising - though I doubt that is the cause of the hum.

Welcome to Beoworld. 

If I replace the RCA cable with DIN I will need a DIN to RCA adapter for my phono pre amp.  I have removed the cable assembly with plans to replace the RCA cables with modern ones with gold ends. I'm concerned about the possibility of damaging the connector at the end where it plugs into solenoid daughter board.  Does anyone have a source for this connector or cable?  Is there a 4002 boneyard out there?

Since I've had this problem for so long I agree that replacing the RCA cables probably won't fix the hum.

There is a chassis/earth ground cable that is attached at a screw that also holds the solenoid daughter board in place.  The other end is attached to my preamp. I have tried replacing that cable already.  Is there a better place to pick up earth ground?

I have a service manual and don't mind getting my hands into this thing.  I know chasing 60Hz hum problems can be a challenge.

This turntable got a lot of use from 1978 to around 1998.  The 20CL is tired but I want to resolve this issue before spending $ on a replacement from Soundsmith.

I used to use my gram with a 'normal amplifier'. It hummed unless I grounded the chassis. AsI only used it infrequently with said amplifier, I simply grounded the chassis from the metal chassis at the rear. Worked perfectly!

I got my O scope out and it basically confirmed what I was hearing.  I get an ugly 60Hz signal on the L + R outputs if I use the chassis as the referance ground for the scope probe.  I think I have a bad cap or something in the regulator rectifier circuit.  Unfortunatly, both circuits are located on the main system board so they can't be isolated.

I will keep poking around and update everyone when I find the cause.

There is an original DIN to RCA adaptor from B&O that provides a separate grounding breakout. I believe this originally shipped with the turntable, at least in the states, as both my 4002 and 4004 have them intact.

The internal connector is just a naked DIN plug, which you can see at the lower right of this picture:

My 4002 has a different soleniod board than that.  There is an inline connector on mine.  That picture brings back memories of my 1st 4002, it had a DIN connector.  It had been modified with a Jonus-Miller tonearm.

The board in your two turntables is probably a lot more common than mine.  I will have to be extra careful when I replace the RCA cables in mine.

At this point I'm going to replace the filter cap in the power supply.

Good thing you brought this up, I just realized that the muting circuit in my "new" 6000 doesn't mute at all, and I just thought it didn't have one in the first place! Better that way, though, but I'll still want to fix it...

The picture above seems to be related to some modification which removes the delay in the muting circuit - is it something I'd like to do in the same time? Is this because the muting contacts might still be closed when the music starts?

-mika