I recently acquired a nice Beogram 8000 with MMC20CL cartridge that has a pulsating hum. The pulsating hum can be heard only through the speakers and only when the needle is on the vinyl. It's one pulsating hum per platter revolution. If I unpause the tonearm and let the cartridge guard rest on my finger without the needle making contact with the vinyl, the hum is not present in the speakers. The pulsating hum is heard only when the needle is ON the vinyl and only during no music or quiet musical passages. This unit has a metal tacho disk. The 8000 was shipped to me with the platter mounted. Any ideas?

Hello, and welcome!

I had this problem exactly on my Beogram 8000!

For me it was a bad solder at one of the connectors (but which one I don't remember!). One drop of solder was all it needed, and that was one year ago! Use a magnifying glass or re-do all solders if it comes to that... Have you changed any caps by the way? Along with solders this WILL cure most issues!

Good luck! And please wait for other ideas before doing anything: I'm sure Peter (the Doctor), Martin (Dillen) or Jeff (Burantek) et al will add their pennyworth too.

Where can I order cap replacements?

Thanks.

The Beogram 6006 and 8000 came with a tachodisc of the photographic type.
This disc has a printed pattern that is read optically and from the opto signal
the processor calculates and corrects the actual platter speed continously.
The photographic type of disc is known to fall apart, the pattern
slides around on the base material and even that material will eventually disintegrate.

With a bad optical tachodisc, the platter motor will produce a sequence of humming sounds consistent with the platter revolutions as the electronics try to correct the speed to compensate for the missing tachodisc pattern readings.
You can hear this if you place your ear to the deck, often also from the speakers
when the Beogram is playing, you can hear an audible wow (piano music is particularly
good for hearing this) and in severe cases the Beogram will also flash and jitter
some digits on its speed readout display to indicate that something is badly wrong.

A bad tachodisc will often be visibly bad.
Lift off the platter and the black subplatter and take a look at the pattern on the tachodisc that sits around the hub.
If the photographic material is flaking and/or the printed pattern is coming off, it will need replacing (most will).
Note that the subplatter has three tiny protruding tabs that needs to fit into
indentations on the hub when you put it back on again.

I can supply both a replacement tachodisc in stainless steel and a capacitor kit.
You can google Beogram tachodisc or Beogram capacitor kit and find more info in some of the top hits.
The solder joints should also be checked, as Jacques suggests, especially at
the edge connectors, in the power supply areas, at the processor socket and
where the ribbon cable meets the main board.

Martin

The tachodisk is steel. I can see through the notches. They are not printed on. When I place my ear to the deck I hear a hum but it does not pulsate. The hum pulsating through the speakers is at the same frequency of what I hear with my ear on the deck. The pulsating hum can be heard only when the needle is on the vinyl during no music or quite musical passages. It is faint but noticable.

Please give me the info to order the capacitor kit. Thank you.

The pulsating hum (unstable platter rotation) is usually either a power supply
problem (capacitors) or a tachodisc problem.
If the hum is consistent with the platter revolutions, the problem is almost
always tachodisc related.
The tachodisc is read by an opto sensor. Make sure this sensor sits apprx centered
over the pattern. Slide it in or out a bit and see if that cures the fault.
Of course, it is also essential that the tachodisc is not damaged, bent or otherwise distorted.

Shipping a Beogram tangential with the platter mounted is asking for trouble
and the main bearing nylon insert will often break which often lowers the
subplatter enough to rub on the floating bottom plate. In severe cases it will
even lock the bearing and brake the hub.
Check that the platter (with a record on) will rotate freely by hand without rubbing on anything.

You have a PM regarding the cap kit.

Martin