Check if one of the switches on the operator panel is permanently activated.
F.eks. the UP switch.

Martin

Hi Dillen

do you mean the operator panel the silver square panel up down/ left right?

Also are you Dillon that you can get belts for systems such as cd 50 and also aluminium strips for Beogram 4002 lids?

Thanks

Kevin

Yes to the panel.
Yes to belts.
No to alu strips, that's Frede of Classic Audio.

Martin

Dillen wrote:

Yes to the panel.
Yes to belts.
No to alu strips, that's Frede of Classic Audio.

Martin

Stripped the control panel and they points were very tarnished but the up and down etc cleaned and the switches were working fine.

I think i can rule out the control panel, i put it back together and all buttons seemed fine, just no action from solenoid.

I feel tempted to point to Sonavors thread.
He is currently working on a Beogram 4000, he is very competent and doing things the right way.

Martin

hey Martin

I will have a search for that, is it just a case of going into his tab?

Hi john,

I have taken on a big challenge,  just aquired a nice BG4000.......but.......

Getting through the fault-finding flow chart alone is not that trivial, for instance what means Q2 = high ?? What's high or low ?? And then there is the circuit diagram........used to find the disignated parts of the CD doing 'automatic lowering', 'detector arm sensitivity', etc is quite tricky.

But back to the trouble my BG4000 showed:

It powers on, carriage moves to the 30cm run-in groove and then stops.....without lowering ?

The carriage can moved with < or >,  reaching the run-out groove but won't return after ES has been activated ???

The only way back is via the >- function.

At no stage can the solanoid be activated ???

I have fine-sanded all brass contacts, lubricated all nipple-witches - nothing supicious there .......

Have to admit with the fault-finding flow-chart alone I won't get anywhere without some assistance from one of your expertise......

Looking forward to an expert-reply

Cheers, ALf

Hi Alf,

the Beogram 4000 is uses some early NAND IC devices in the control panel to manage the logic for the control signals. Those "Q" signals are derived by the BG4000 control panel NAND gates to control some of the transistor switching on the main board. For example the Ǭ₁ signal controls the tonearm solenoid by turning on/off the 1TR10 transistor.  The "low" values are typically around zero volts and the "high" values are around 6 volts. But the function of those signals are Boolean, one value or another.

I haven't had the exact same problems as you regarding the tonearm lowering but I did have a case where one of my BG4000 turntables was not lifting at the end. I verified the ES button was triggering but it didn't work correctly when the turntable was in operation playing a record. The problem turned out to be the metal bars that travel and press down the plastic button (nipple-witches you called them). The metal bar for the MV button was slightly higher than the others. It took readjusting those metal bars to get my Beogram working properly again.

That can be the difficulty in getting these turntables back to perfect operation. A lot of mechanical adjustment and readjustment is necessary.

Try running the turntable without the platter on so you can get measurement probes on the control signals. With the platter off the Beogram will think there is a record in place and try to set down and play. You will be able to check out the control signals involved for each state. Monitor the base of 1TR10 and/or the point between 1R25 and 3IC1 (Ǭ₁). See if the voltage of that signal ever changes. Ǭ₁ causes the tonearm solenoid to engage when Ǭ₁ goes low (zero volts). When it goes high enough to turn on 1TR10, the tonearm solenoid disengages. The OFF signal, ES signal and DS signals (that feed 3IC1) need to be at a logic high for Ǭ₁ to be able to go low.

John