Beogram 6500 performing erratic

[alf]

Hi All,

just when I thought everything is back to normal…..it isn’t !

press Turn and the pickup arm moves to the drop down point,

press Play and the PUarm lowers and immediately rises again, goes back t9 its resting position, rises the PUarm, lowers it again and after some attempts of pressing Stop the arm finally goes to its resting position but stays in powered position.

while this is happening I can hear the spindle attached to the servo motor tries to klick into gear after a couple of tries and finally manages to do so…..

it is quite difficult to explain what is happening here and I wonder if it could be a fault microcontroller (the 24-pon chip on PCB 1) ?

none of the gear wheels is damaged, the magnetic coil on PCB1 is ok

to the point: I have no idea what is going on and what is causing that
erratic performance.

can anyone shed some light on this problem ?

ALF

 

 

 

[filip_kbh]

It probably resembles the issue I had with my BG7000, and Martin (Dillen) answered that I should clean the switch near the top left of the deck – it’s marked S1. This helped.

Location: Copenhagen

[alf]

Hi,

thank you for your reply, certainly always good to have clean contacts !

i am afraid but I decided to reset the cam-wheels as per service manual – I wished that manual is a tick more understandable using phrases like ‘….opposite h9le J’  when it actually means overlapping holes !! It can easily be misunderstood…never mind, I got it now.

in theory resetting those cam-wheels should fix the problem – I will report back.

ALF

[alf]

Hi All,

finished the process of re-fitting all cam-wheels as per SM. Sadly the table still plays up.

looks like the next move would indeed be the removal of board 1 and give those switches a good clean ?!?

i do not feel overly confident this will be the problem fix as the table was working fine just before all this

started……but I shall try and will report back.

In the meantime please do not hold back with pointers …..

ALF

[alf]

Sorry, I forgot to mention the table has had a complete recap – so, that should not be a problem source.

ALF

[alf]

back from the workbench  after cleaning the 3 switches but no luck. The PU arm moves in, lowers but rises straight after again and so forth …l

i begin to wonder if the magnet inside the coil is moving as it should to move those two control arms for two

of the cam-wheels ?

one other question: does the hook of the metal rod which lifts and lowers the PU arm need to sit behind or in front of the white plastic rod the runs behind the PU arm assembly ?

your expert advice is badly needed 😁

thank you, ALF

[alf]

back to testing:

RL1 and RL2 seem to be controlled by TR4 and TR5 if I am not mistaken.

the question I would ask do those two transistors have to be closely matched ?

in my case they are about 15% apart in their hfe values  ?!

i simply can not find anything wrong with the cam-wheels as i checked their fitting as per SM.

the cam responsible  for the lift & lowering just is not stopping as per correct sequence.

hard to believe no one has any ideas or pointers to help with that issue………too hard perhaps I wonder ?

ALF

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