[Dillen]

Note the note about cable and socket matching here:

https://www.beoparts-shop.com/product/cdm12-4-laser-module-beocenter-2300-2500-beosound-3000-4000-ouverture-a-o/

Martin

[Dillen]

You don’t replace it – it must be taken apart, cleaned and lubricated. It can all seize up
in dry lubricants.
New idler wheel, new lifting arm friction pad and a new belt.
The motor will almost surely also need new bearings in order to run correctly.
All of these parts are available.

Martin

[Dillen]

No! Not the circuit board (that’s not an easy task).

The large dial panel = the large black metal facia with the white lettering/frequencies
and channels, that the sliding dial pointer travels on, – that also holds the lamps.
One screw each corner of the panel (= two screws each end of the Beomaster).

Martin

[Dillen]

The large dial plate will have to be losened.
That’s four screws from below.

Open the Beomaster and swing the bottom section away from the top section.
Push the dial pointer to a place where you can access its fastening to the string.
Mark up on the string where it is fitted to the pointer so you can fit it back in the
same place, remove one of the two small screws and losen the other so you can
swing the small clear plastic string holder away from the string which zigzags under it and between the screws.
Then take out the four screws holding the dial plate.
When done, make sure to align the dial plate correctly, so that both the dial
pointer and the sliding knobs are free to travel.

(Same procedure for Beomaster 1200).

Martin

[Dillen]

Yes, that’s correct. Both sideways and up/down. The metal “ears” mustn’t touch.
And it should be when the deck is upside up (not upside down as in your photo).

The bushings are actually for transport safety, because the heavy motor would be free to
swing around pretty wildly in transport, if they weren’t there to limit its movements.

Martin

[Dillen]

The important thing is that the motor bracket is free floating, and its
metal “ears” will not touch the nylon bushings (or you will hear rumble/whirring/running noise).
If, when you have put it all together, and the deck is in its normal upside up position,
the metal brackets are close to the bushings, you could try swapping the two bushings
and see if it ends up better centered.

There can be a washer under the nut as well.

Martin

[Dillen]

The arm position is controlled by a steel rod running in a groove in a cam wheel.
It could seem to be put together wrongly.

Martin

[Dillen]

Any passive Beovox models would suit it, really.
But Beovox S45 (Type 6302 or 6312) springs to mind.

Martin

[Dillen]

Mark, welcome!

Martin

[Dillen]

Fit a screw M3x10 or so through the hole from below, put a washer and a
nut on top and fit the
string loop and the spring to the excess upward pointing screw thread.
Adjust the setdown points.

Martin

[Dillen]

Keep in mind, that if you measure across one component in a circuit, you may actually
measure others as well, because they are connected in some form.
Another thing is polarity; If you compare ohmic measurements make sure you have
the same polarity when measuring in both channels. A semiconductor may conduct current
in one direction and not the other, and that could give a difference in the readings.

Resistors wouldn’t be the first components I’d suspect.
And they will usually go open circuit or high in value – not low.

Martin

[Dillen]

A flashing speed indicator indicates that the repeat function has been activated (you pressed Play more than once).
The cartridge rides high as the cantilever suspension losen from the micro cross inside
the cartridge and falls down.
Next step is that the cantilever falls off entirely.
That will happen very soon. Get it re-tipped.

Martin

[Dillen]

Are you using an original B&O Beogram datalink cable?
If not – that would be a clear reason.
You cannot use a Beocord cable as it is not double-shielded.

Martin

[Dillen]

Check the switching ICs. Power and shorts (oxidation on pins).

Martin

[Dillen]

One or more components being pushed by the frontpanel so something shorts?
Perhaps a component fitted too high?

Martin

[Dillen]

Yes, I would suspect the IC before any of the small transistors.
Put a scope to the L/R signals from the IC and you will see.

Martin

[Dillen]

A bad MPX chip wouldn’t be a first.

Martin

[Dillen]

Ralph, nothing seems to be missing in that area.

Martin

[Dillen]

Yes.
Red drops.

Martin

[Dillen]

They are tantals. Tiny drop-like components.
Make sure you get their polarity right or they may go bang.

Martin

[Author]

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