I did a test. Cut the red +24V wire from the reed "always on" switch and temporarily connected with the +24 grey wire on the other working relay: everything fine, lamps off when TT is in standby and lamps ON together with motor, strobe and arm pressing ON.

I ordered some new 2x14 mm glass reed contacts hoping they will fit and work. Many thanks to Martin who provided the possible solution.

I will update the post when the switches will arrive.

Actually, I think Craig was ahead of me with 20 minutes or so. 😂

Martin

Yeah, sorry Craig..

But you saved both of us Martin, we didn't know the Reed tubes are replaceable 🙂 It will be a late night, keep-calm affair (those tiny coil wires are so close to the tubes soldering points..) but let's give a try.

Hello again,

reed switches arrived and carefully fitted in the relays. Everything fine, now the BG shuts off and powers on how it should. Thanks. 

Another couple of issues to solve, the main is 7" records not recognised. I will search across the forum before asking your help again.

Old reeds removed:

New reeds in place:

TT spinning again:

Good job......I'm also going through the detection arm issue so will keep abreast of each other. I do have a set of B&O training notes which provide a good amount of detail on these circuits (donated by solderon)….I have forwarded these to the site for inclusion in the service manual area in the fullness of time, however if you would like a copy now email me.

Craig

Thanks Craig. I could find the problem related to unrecognized 7" records. It was simply the spring that should press the corresponding button on the arm contacts board which was not low enough to be effective. Sorry I didn't took photos -I will do tonight- but it is the first button from right on the board (the only in grey color in my 4000, others are red).

A little bent on the spring, wich is flat on below contrary to the others that have a 45° angle shape, cured the issue.

But I have another question: when I keep press forward manually, the arm travels across all the rail (and this is correct) but does not have a safe-stop at the end.The arm motor keeps turning until I hold the key pressed, even if the arm it's at the end of the rail. 

Shouldn't it have a safe-stop at the end of the rail? In auto-mode everything is fine: arm stops, lifts and go back.

Roberto

Just to complete, time for final adjustments before connecting to an amp...

- re-checked motor supply voltages, frequency and distortion. I lowered voltage to 6,10 volts @33rpm just (manual says not to go over 6,5V so I guess

6,1 it's a safe and good voltage). Clean sine-wave, no distortion here.

- checked arm alignment, adjusted arm height, and zero-balanced it.

- adjusted 7", 10", 12", start  and stop button-springs positions and tested with different records.

Here testing the BG 4000 with a 10".  

Late enough here, so will enjoy a good rum. Goodnight

Fantastic pictures. I had one of these BG's many many many years ago, in fact it was my first Bang&Olufsen item. I regret I sold it.

I do, however, prefer the 8002 now - much easier to maintain due to less electronics :-)

From the last two pictures it doesn't look like the cartridge mounts/mates to the tonearm connector correctly. Is that something you were planning on fixing?

-sonavor