Sound like an opto fault.
Replace the tacho IR sender LED.

Martin

Thanks Martin,

i presume you are talking about the bottom part of the speed sensor ?!

would a OP240C work and if Yes, wouldn’t I have to replace both partnering the Sender LED?

again thank you for your advice

ALF

OP240A, if I remember correctly, is what I use.
There is only one sender LED. The top one is the receiver and I never saw one of them go bad yet, whereas I have replaced many senders.

Martin

Interesting exercise replacing the sender LED in the speed sensor.....but

yes, its a but.......the BG simply won’t shut down.

the moment I plug it in the platter spins madly - I can operate play...the carriage does everything right

arm lowers where it should, activating stop brings it back to its resting position however the platter keeps spinning

and the servo bulb  remains on ??

well, back to the drawing board and studying the technical product info.....

does not look like just a break issue but on/off as well 😡

shall I wish Denmark best of luck in their ⚽️⚽️ encounter against AUS ??

Martin, are you listening ?😁

ALF

Hi everyone,

after further investigation the platter still spins out of control after connecting the table to the mains voltage.

activating PLAY and all moves into position etc except the platter, spinning madly - in this case

according to the drive system preamp the gate at TR26 should go positive but shows  -9 VDC ? 

Going negative means the platter spins too slow .....which is not the case !

that is one issue !!

the other issue is the table is not completely shutting done after STOP is activated ??

servo light remains on at end position and platter keeps spinning anti clockwise ?

reactivate PLAY the arm moves in position, platter spinning anti clockwise.....

i can break down the platter by hand and it starts spinning correctly.....well, until it goes mad again.

am I wrong barking at the Brake Circuit ???

your thoughts ?

ALF

Next step in the investigation:

looking at the Brake Circuit again....

at record play-out stop the base of 1TR31 should see a low level...checking 2IC1 Pin 37 voltage at stop

goes from 5V down to 0.7V but the base of 1TR31 never sees that low level...why ??

instead base of 1TR31 goes down to 4.4V and platter spins anti clockwise....great 😡

back to work....

ALF

Seems like everyone is on holidays or at the world cup ?

well, no curther progress I am afraid and it is indeed very hairy to describe a such irratic behaving machine accurately !

my money is still on the drive / brake circuit !

0TR2/3 are new, 1TR29 & 30 tested fine, still under suspicion is 1TR26 and 1TR 27/28/31 all tested fine and 1TR33 is new.

That puts 1TR21 ON/OFF also in the frame as the table does not entirely switches off ?!

i do not neccessarily suspect the uP

as always, comments and ideas are most welcome - don’t be shy 🙄

ALF

Seems like everyone is on holidays or at the world cup ?

well, no curther progress I am afraid and it is indeed very hairy to describe a such irratic behaving machine accurately !

my money is still on the drive / brake circuit !

0TR2/3 are new, 1TR29 & 30 tested fine, still under suspicion is 1TR26 and 1TR 27/28/31 all tested fine and 1TR33 is new.

That puts 1TR21 ON/OFF also in the frame as the table does not entirely switches off ?!

i do not neccessarily suspect the uP

as always, comments and ideas are most welcome - don’t be shy 🙄

ALF

If your deck has the extra 4013 IC in the feedback circuit on the piggyback-board in the processor housing, check that IC.

Martin