ARCHIVED FORUM -- March 2012 to February 2022READ ONLY FORUM
This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022
Hello Beoworld,
I am trying to solve an arm lowering problem on my 4002 Beogram.
It seems that the copper damper is malfunctioning.
The piston will sink into the cooper damper, but will not moove out again when lowering the arm, (selnoid activated), it's like a vacuum, no air will flow back into the copper damper.
I've dismantled the copper damper, it has a rubber washer(valve) on the end of the rod going through the piston, that allows air to escape between the rod/piston assembly on compression. There is also a spring on the other side of the rod that keeps the valve closed when no force is applied . In this position the arm is up and selnoide not activated, as it should.
But how does the air enter when the arm is lowered, selnoide activated ?
Since the valve is closed when the piston is being pulled out, no air can enter from the rod/piston.assembly.
I noticed there is a waxed filled hole on the end of the copper/plastic assembly, which might hide an adjustment screw, but i haven't touched that.
thank you for any help on this.
Hello Freddy63,
You are correct, there is an adjustment screw in the wax filled hole. I'd recommend to get the whole cylinder cleaned through and relubed with acid-free oil to lessen the friction.
Vinyl records, cassettes, open reel, valve amplifiers and film photography.
Hello Soren,
So i have to break the hard wax sealing so that i can get to the screw ?,
I guess that means that there's a seccond air passage controlled by that adjustable screw allowing air into the copper cylinder so that the piston can moove out.
Something must have clogged the air passage as it is completely airtight on that end.
I'll try using my air compressor to shift dirt before breaking the wax seal.
Thank you for your reply.
You're welcome, but be careful when using compressed air as you may break it - you have to readjust the airflow if you use the screw, which I think you have to do nevertheless
I think i'll take your advice and not use compressed air.
Also i think it it would be usefull if i upgraded to silver membership at some point, so that i can have access to service manuals.
I have to change capacitors on my Beovox(S45 and S60 and 2600).
Beomastster 2400 may also need some attention and Beogram 4002.
I'm a novice in electonics but i like learning.
I've bought a soldering station, multicore soldering wire, a good multimeter and i'm going to order an esr meter.
I'll take some pics and post them on the forum when i get round to it.
Does the tonearm move freely now that the damper is out?
Jacques
Bonjour Jacques,
Yes it does moove freely, i can't feel anything sticking, just the force of the spring.
By pulling the spring loaded lever, the tone arm mooves freely.
Here are some pictures although you can't tell if anything is mooving freely from these.
tone arm 4002
Hello again,
I've also noticed that the photo-resistor lamp on the acrylic ruler does not light.
It's strange that when i play 33" and 45" l LP's the tone arm will go to the right position.
Anyway, i tested the votage on the lamp 1.164 V, but i don't know how to test the lamp in the circuit and i'm not sure what the lamp is..it looks like a led.
Any advice welcome.
That is a LED. It's infrared so you cannot see it with the naked eye (try a mobile phone camera). Some models had LEDs in that application, others had incandescent bulbs. You don't need to worry about that part if the tone arm carriage stops at the right spots and the speed changes before the 45 edge.
--mika
Make sure that you thorroughly clean the pivots/arms pointed by the red arrows. Underneath you will find old hardend grease.
Thank you for that information, Tounedos, one less thing to worry about.
So, i've cleaned and lightly oiled all pivots/arms as Beobuddy pointed out.
I've also scraped off the hard sealing wax (carefully) on the copper damper, unscrewed the adjustment screw, cleaned everything and very lightly oiled the inside of the copper damper. I've adjusted the copper damper so that the tone arm will lower in about one second.
I put a record on and pressed start., everything is working again.
At fisrt there was a low hum coming through the speakers on all settings(Phono, Tape , FM), but it's gone now.
The sound quality on Phono isn't very good, but on the Tape and FM it's ok.
When i have some more free time, i'll get back to my B&O restoration. I've bought a house, but it needs a lot of work(new roof, plaster board, electricity, etc.)
Thank you all for you help and knowledge.
Frederic.