[Dillen]

69er, can you show us a photo of the board (front and backside)?

Martin

[Dillen]

I have never seen a tray belt cause a read failure.
If the belt fails, the tray will usually not open fully – or not open/close at all.
If the tray doesn’t close fully, the disc will not start to spin.

The symptoms of the disc spinning for a few seconds, not reading and then stopping is a sign of a laser starved of power.
Replacing the capacitors on the servo board will alone fix this in 95% of cases.
The last 5% is usually dirt on the laser lens or a combination of the two.

If the disc doesn’t start spinning at all, there could be a problem with cracked solder joints (as shown above) or
a badly seated ribbon cable for the disc drive.
The laser itself rarely dies. I don’t recall ever replacing a laser in one of these decks, and I’ve done many.

Martin

[Dillen]

Most likely not the set with the collared bearing.
As mentioned in the bearings sets descriptions, you will have to look at the motor to see
which set is needed.

Martin

[Dillen]

Sure you have the tapes playing side against the tapeheads?
The tape could be twisted so it has the backside against the heads.

Martin

[Dillen]

Remember lubricating should be with an oil suitable for use with sinter-bronze. It needs to have the
right additives. Lubrication is done with the bearings submersed in the oil, while vacuum is pulled to get
the air out of the pores in the bearing metal. Then leave them submersed without vacuum for 24 hours to allow
oil to suck in.
If not oiled correctly the bearings will only run fine for a short time (hours or days).
Factory new bearings, pre-oiled and ready to fit is available from Danish Sound Parts.
I would recommend that as it also includes new reservoir felts and takes wear to the old bearings out of the equation.

Martin

[Dillen]

A photo or two showing how far you’ve come would help us suggest the next step.

Martin

[Dillen]

Dismounting the servo circuit board from the bottom of the disc drive you must work carefully.
You will have to release the ribbon cable running to the laser block from its socket on the pcb.
This can be tricky – particularly because the cable will almost certainly break at the sharp corner where it’s secured, if pulled.

Martin

[Dillen]

Correction: It cannot be from a 606 due to the different pivot system.

Martin

[Dillen]

It could be from a GR 605 (1959) or 606 (1960).

Martin

[Dillen]

Put a scope on an output.
Check for oscillation.

Martin

[Dillen]

Martin

[Dillen]

The modern grey stuff often sold for use with computer CPUs is useless. Some of it dries hard over a week or two.
Silicone pads – some are fairly good, others are junk. I don’t like them, and I throw them away on sight.
The original white heatsink compound, that was also used originally, works best. It will last for decades.

Martin

[Dillen]

A drifting idle can be caused by bad thermal contact to the heatsink.
Did you use the proper white heatsink paste?

Martin

[Dillen]

A worn and slipping belt can allow the motor to accellerate to easily.
The motor pulley simply slips on the belt at startup.

This, coupled with electronics that will accept to lock in at twice the correct speed, causes this.
The cure is to replace the belt.

Correct belt here.

Martin

[Dillen]

I use a “glass-hair”/fiber brush.
But if there is oxidation, you can clearly see it as black flakes.

Martin

[Dillen]

Welcome back, Peter!

Martin

[Dillen]

Difficult to say what could be the reason, but if you start working or diagnosing keep in mind that Beomaster 900 has positive ground.

Martin

[Dillen]

Typical sign of aging capacitors. Grab a service kit and replace the lot.

Martin

[Dillen]

Does your volume control have one or two ICs?

Martin

[Dillen]

Thanks Mark.

Martin

[Author]

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