Beogram 4002 sensor issue

My repair guy is struggling with repairing my BG4002 because there is no avaliable repair manual for that particular serial/model number.

The issue is that it will not register if it plays a small vinyl, so the needle will drop at the beginning of the metal platter.

Any advice on what to do here?

Here is a picture of the sticker he said is different from others

Sorry, wrong sub forum. Will post in Beogram

(Moved to Beogram section).

If it tries to play an empty platter, the record sensing system is at fault.
- Bad or wrong lamp.
- Incorrect placement of lamp.
- Bad sensor.
- Bad adjustment of sensorarm height.
- Bad capacitors on main board.
- Any combination of the above.

Martin

Is it possible to get a description of what capacitors that should be changed?

He says it is something I. The motherboard that needs to be changed, but he can’t measure what.

Let the sensorarm hover over the radial streaks of an empty platter while it rotates.
Watch the signal on a scope and compare to the servicemanual (yes, it exists).
Collector of TR3 should show healthy 0-6V pulses.

Martin

Which service manual is it that goes with mine?

That portion of the circuit is unchanged in the various Types for the 4002. 5503 is fine. No need to change the motherboard as its fully serviceable.

I agree.
Only the component designators vary, but you should be able to recognize the signal pattern.

Martin

Thanks guys, I’ll keep you posted