It seems as though you may have a problem with the pick-up?The stylus suspension becomes stiff with age and less compliant than it needs to be.

Can you try another pick-up?Is the tracking weight correct?Are the chassis transit screw's fully released?

The pick up follows the groove across the record,and as it tracks,it operates an optical sensor which triggers the carriage servo motor to drive the arm inwards,and keeping the pu arm roughly in paralell with the indicator arm next to it.You should be able to see  this in action as it triggers approximately once every revolution of the record.

If the pu arm is being drawn way out of parallel,you may have a problem with the optical sensor system,but it may only need adjustment.

Nick

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Thank you for the response to my request. I have been through a whole process of suspicions before I arrived at the tracking possibility. It all started when I bought a reconditioned cartridge from FJS in Germany, and I found that there was a problem with the sound on one channel – my first reaction was that the cartridge was faulty, but after speaking to a few people I realized that it could be due to other things, e.g the tracking of the tonearm. I cleaned the slider bar for the tonearm and regreased it, and found that I had sound on 2 channels( although the sound wasn’t perfect). When I tried playing a few records I found that some of them played  all the way through and some had a problem with the tonearm sticking. It seemed that the longer the playing time( and therefore the less the spacing between tracks) the tonearm was prone to sticking. It seems I need to adjust the optical system, but until a week ago I didn’t even know how the tracking system worked. So I need some advice on how to go about checking the tracking and how to adjust it. I have seen that when the stylus sticks, the pıckup arm is not tracking.

As for all the other points you mention – yes, I have checked all  of the obvious things.

It seems I need a special test record to set up the tracking properly, but I don’t possess such a thing, nor is it possible to obtain one, as far as I know. If you can indicate how I can set the tracking without the disc, my immediate problem will be solved I think.

Many thanks once again

Alan

I strongly suspect the optical switching system -  I have tried the diaphragm adjustment, but made no improvement. On certain records(all new ones) it appears as thought the tracking motor is not switching on at all, on other records there is no problem.  Could it be that the optical switch is dirty and just needs cleaning? Or do I need to try and find a replacement tonearm?

You need to try another pick-up!!!

In my experience,this machine is very reliable,and what you describe,has all the symptoms of a faulty p.u.

Can you return it ?

Nick

yes I can - I bought it from FJS in Germany, and he has accepted to take it back and check it out. Tomorrow I will mail it back to him.

Thank you very much for your help

Alan

Could be the servo motor bearings in need of cleaning and lubrication.
They tend to bind as their oil dries.

To diagnose it, put a voltmeter across the servo motor and watch the voltage while playing.

Martin

aldo wrote:

I strongly suspect the optical switching system -  I have tried the diaphragm adjustment, but made no improvement. On certain records(all new ones) it appears as thought the tracking motor is not switching on at all, on other records there is no problem.  Could it be that the optical switch is dirty and just needs cleaning? Or do I need to try and find a replacement tonearm?

Beogram 3500 does not use optical system to my knowledge. In the tonearm assembly, there is a switch that is triggered by the angle of the tonearm, and then engages the motor for moving the tonearm assembly.

Someone correct me if I am wrong, but I have been through a lot of these identical 35/45/65/7000 Beograms, and they all use the same tonearm assembly.

/Jacob 

Dillen wrote:

Could be the servo motor bearings in need of cleaning and lubrication.
They tend to bind as their oil dries.

To diagnose it, put a voltmeter across the servo motor and watch the voltage while playing.

Martin

Could it also be a bad belt for the tracking motor ? If it slips, the cariage would not move as intended ?

/Jacob

Belt is possible.

Tracking is optical.

martin