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I am wondering if the damper piston and rod got damaged at the time when the metal lever arm got bent (shown earlier in the thread). Some sort of stressful event happened with this Beogram to bend that metal piece. It would make sense that damage may have occurred to the damper piston assembly at the same time. You will need to disassemble the damper like Søren's picture and closely look at the piston assembly to see why the rod is loose.
-sonavor
sonavor: I am wondering if the damper piston and rod got damaged at the time when the metal lever arm got bent (shown earlier in the thread). Some sort of stressful event happened with this Beogram to bend that metal piece. It would make sense that damage may have occurred to the damper piston assembly at the same time. You will need to disassemble the damper like Søren's picture and closely look at the piston assembly to see why the rod is loose. -sonavor
Sorry, Plunger = Piston, In English sometimes I dont find the right words must be Alzheimer or just getting old
Collecting Vintage B&O is not a hobby, its a lifestyle.
Hi guys
ive been a little snowed with work at the office. I'll have a look today or tomorrow. Should the plunger indeed be damaged.. And keeping in mind that the valve screw is broken.. Where would I find a replacement part?
Steve
Hi everyone
So I've taken the damper apart as suggested and found the following -
valve screw turns but does not adjust - covering hole at back makes no difference to piston movement. It's difficult to move the piston regardless of whether hole covered or not.
The seal at the bottom of the piston seems intact.
in my mind, there are two issues:
1) the damper valve screw plastic stripped and screw won't move.
2) the damper piston thus doesn't move easily (and didn't in the beginning, even when the screw was in its factory position and when I UNSCREWED it, before it stripped).
what is happening and did happen from the beginning, is that, when the tonearm is lowered:
1) the solenoid clicks and the mechanism move as it should
2) tonearm bounces down onto record as a result - , because the damper, despite the piston being stiff, pushes the tonearm down. The shaft of the piston, which carries the spring in the damper, pulls out to a point - enough to move tonearm down without the piston itself moving smoothly or at all.
So with the piston out of the chamber, you can pull the rod and it will move out of the piston? In other words the piston can remain stationary and you can still move the rod.-sonavor
Yes - it's not tight - loose, if that makes sense. This 'play' is enough to push the lever which drops the tonearm. Two extreme positions:
Is this normal?
Here a pic with the mechanism in rest position, the piston shaft is out and the valve inside the piston is closed, activating the solenoid will move the lever below the solenoid, the left spring gets more tension and pulls on the shaft, the piston moves out slowly if the adjustable air valve is correct adjusted and the air relief valve inside the piston is closed.
If the air relief valve inside the piston is damaged the air will escape through the valve and the piston will move fast, to test it put the piston valve end to your mouth and blow, if air escapes the valve is bad.
You dont need to power up the deck to check to check the function, just pull the lever below the solenoid with a finger
To me the piston valve doesnt look right
Here is a close up of a BG4004 piston and rod. There is a little play in it as determined by the spring.The movement of the rod shouldn't engage the tonearm lowering lever. the distance there should be from the rod and piston moving out of the chamber at the speed set by the air valve. If the slight movement of the rod is tripping the tonearm lowering lever then that lever position is not adjusted correctly.Maybe the original owner messed with all of that...hence the bent solenoid control arm and the arm lowering mechanism.
Test your damper again to make sure it is bad. With the valve screw out, you should be able to easily move the piston in and out of the chamber. When the valve screw is screwed in where the top is flush with the top, the piston should have noticeable resistance but should still be able to move.If you can't get any position of the valve screw that affects the resistance on the piston movement then you will need to determine where the air leak is. Possibly it can be repaired. Otherwise you will need to try and replace the damper mechanism.
Thanks all. It seems there's another problem - I've set the mechanism back into place and the solenoid is now not functioning. I was extremely careful, however I've clearly knocked or done something in the process. After such success in repairing the Beocenter 9500, this 4004 project is starting to look dismal.
Here is a video of where it now stands:
http://youtu.be/uL-d4zywFAk
On the damper:
Blowing on the end containing the seal: no air escapes.
The screw does not move up and down on the casing, so not able to adjust this valve
I haven't even looked at the tonearm lifting /dropping mechanism and the adjustment of this in relation to the damper / damper rod/arm.
The solenoid issue is now an additional challenge in this. I am determined, but I do think I need to find a replacement damper.
Good news - I've sorted out the supposed solenoid issue. It turns out that there was a damaged wire to the sensor arm bulb. I'll fix it later but for now it's working- after some jiggling - see the 'cut' in the wire below. I noticed it at the beginning of the project, but I didn't think that it was bad enough to affect the connection. It was preventing arm from dropping. Video showing the damper and solenoid mechanism in action: https://youtu.be/3CI3z1MX5wI
The damper has square hole at the base where the adjustment screw it located try to cover it with a piece of tape and see what happens
Did try - no difference unfortunately.
what would you suggest as a way forward? A replacement damper/damper case?
Apparently the adjusting screw for the air valve is turned all way in or the threads are destroyed, if you cant get the screw out I dont see any other solution than try to find another damper, try Martin
Thanks Søren - I'm fairly new here - how would I get in touch with Martin? Can I search for him in order to DM?
Martin is Dillen on the forum Start a conservation or send him a mail
I'll do so. Thank you!
So I've managed to source a damper, which is fantastic news! Awaiting delivery now -
i have in the meantime tried to play a record - outside of the damper issue, all works fantastically well - except for:
needle keeps skipping back a groove (i.e. Plays the same groove again and again and doesn't move on) - this happens on all records I've tried . - particularly in lead in and lead out record grooves.
If if I drop the tone arm without a record (or metal plates installed) and push tonearm left- the servo motor does indeed move - and speed varies according to 'pressure'
any thoughts? Is this a cartridge / needle issue, a tonearm weight issue, or a problem with the servo or sensor?
Problem solved. Found the problem - thank you!
What was the problem ?
More damper woes affecting tonearm. I've managed to find a damper which is fantastic! Cannot wait to have her working again. She's all cleaned up, and all other elements are working. I've had to remove the two DIN pins though.. Beocenter trying to control Beogram using Datalink was odd: the keys on Beocenter - left and right - weren't controlling the system correctly.. And it was just behaving a little strange (suddenly the tonearm up/down key wouldn't function. Began functioning again when unplugged). Are there incompatibilities between Datalink on these two systems?
Steve: the keys on Beocenter - left and right - weren't controlling the system correctly.. And it was just behaving a little strange (suddenly the tonearm up/down key wouldn't function. Began functioning again when unplugged). Are there incompatibilities between Datalink on these two systems?
the keys on Beocenter - left and right - weren't controlling the system correctly.. And it was just behaving a little strange (suddenly the tonearm up/down key wouldn't function. Began functioning again when unplugged). Are there incompatibilities between Datalink on these two systems?
Yes, these first decks with remote control are not compatible with the Datalink, which age began a few years later. The 4004 is made to be controlled via Beomaster 2400-2, which has ultrasonic remote.
Chris