Hi,
I haven't encountered that kind of failure yet but I would have to suspect an electronic problem rather than mechanical. You will need to dig out the service manual and check the circuit involved.

On the adjustments for the set down point, section 4-3 of the service manual shows that adjustment procedure. If you don't have a service manual you can get a PDF version of it with silver level membership on Beoworld.

-sonavor

Thinking more about your problem with the arm in the lowered position, then raising and lowering again...
I wonder if the problem could be with an unstable solenoid circuit. On those turntables, when the command to lower the tonearm is made, there is a solenoid that activates to move the mechanical lever to lower the tonearm. After the solenoid is engaged it remains in the activated position via a circuit that holds the solenoid in that state until the raise tonearm signal is received. Perhaps that holding circuit is dropping out, then comes back on its own?
Maybe Dillen has seen this type of problem before.

-sonavor

Contacts in the up/down switch on the operating panel too close?

martin

Check your main power lines for micro blackouts

Update; Now that I have decided to find the problem and posted this thread it has not lifted during the last 3 lp's I have played!!.

I did remove the covers and platter and did see that the solenoid has been replaced as it had the plastic arm that liked to smoke them. I also see a lot of hand soldering from the factory that  looks cold. So I think I will re-solder the solenoid and maybe the dull looking connections to see what happens.

Thanks for all of your replies.

In resoldering I would just apply some new flux and touch up the existing solder joints. Don't just reheat the existing solder joints without flux. You may have already planned to do it that way but I thought I would mention it anyway.

-sonavor

Last update. I re-solderd the solenoid leads and it has not lifted while playing. Now playing like it was new!!

Thanks for all the help.

Well my problem is still there! After re soldering lots of connections and checking everything I know, I'm stumped. As I said the problem is very intermittent and lasts for only 1 to 3 seconds then nothing or up to 3 records then it will happen twice in the next.

What I have done, re solder connections, re cap every board, spent hours watching my scope to see what is happening and this is what I have found.

Solenoid Circuit starting with 1Tr14- no change at the base, collector rises to .81. 1TR15- base goes to .31, collector goes to 17! (checked many times) 1TR16ends up with 17 volts at base, emitter & collector (I replaced 16 with no help), 0TR4 ends up 17 volts at the base but shuts off?

As the problem only lasts 1 to 3 seconds it's hard to get measurements. My volt meter is too slow to get a full reading so I  use my scope to check and I'm lucky it has a memory to look at.

The other thing I have noticed during this is at the base of 1TR15 during normal operation it looks like a high frequency oscillation and when the problem hits it goes away.

What gets me is that with 17 volts at the base of 0TR4 it should be turned on but the solenoid shuts off like it"s turned off!

I have checked all ground connections and found 1 bad one for the optics in the tone arm but no help there.

Any help is greatly appreciated.

Jim.

Normally I would offer to hook up a working Beogram and check my voltages for something to compare yours to... but I am afraid I won't be able to do that for a few weeks as I am swamped with projects I am currently in the middle of. If you can post a diagram of the circuit you are measuring and monitoring it might help someone on the forum come up with some other things to try.

-sonavor