Welcome to Beoworld !

There's no photodiode. It is a filament lamp and a voltaic cell.
I suggest you check the lamp first. Does it light up ?
If not, replace the lamp.
If it does, check its position in relation to the lens system. It should have its filament centered right above
the lens and sit as close to the lens as possible.

Still no luck, you need to put a scope to the sensor output and follow the signal through the filtering etc. to see where
in the electronics it is lost.
The radial streaks of the platter gives a nice pulse train for reference.

Martin

Thanks for your reply Martin!

The lamp does light up so I'll have to see what the inside of the detector arm looks like.

Could you tell me how to take the inside of the detector arm out without the risk of damaging anything. I have carried out some repairs on the Beogram but never had to do anything with the detector arm.

Hopefully I won't have to check the electronic circuit because that will be too much effort.

Job

The whole arm insert with lamp, lenses etc. pulls straight out from the arm housing.
The leads are not very long though, just long enough to get it out and rotate a bit so do be careful.

Martin

Thanks a lot Martin!

The lamp was a bit out of position, but one of the legs of the lamp was too short so I had to unsolder and solder it again to gain some length.

Eventually everything is in its right place and the turntable works like a charm.

Thanks again :)

Job

Wonderful !
Don't be a stranger now.  🙂

Martin

jozo wrote:

Eventually everything is in its right place and the turntable works like a charm.

Thank you for posting the result, it will help others with the same problem