I've noticed that the lowering rate of the pick-up arm of my Beogram 8002 is much quicker than I think it should be - in fact there seems to be little or no damping going on at all.  How damped should the lowering device be on this turntable?  I am concerned in case it damages the MMC2's suspension.  

I have checked this site for hints and the only issues around lowering appear to be about the solenoid not operating to lower the arm at all.  The solution to that seemed to be applying something like sewing machine oil to free up the mechanism.  I need to slow it down, not free it up. 

I've also checked the service manual on site, but that isn't quite clear, at least to me, a technical incomptetent.  It would also seem to indicate that any work would require dismantling of the arm, something I wouldn't want to undertake on this particular machine. 

Any thought or ideas gratefully received.

Cleve

 

 

The arm on my BG8002 also drops very fast, it made me wonder too. But when I look on youtube at the BG8000/BG8002 movies there, they all seem to do it, so probably no problem?

I read on beocentral the solenoid for the arm is accurately controlled by the processor, maybe it drops fast and does the last tiny millimeter slowly and controlled, but difficult to see because the distance is tiny and still pretty fast?

Hi,

I have had the same problem with my Beogram 6006 and 8000.

It isn't normal at all, but I couldn't find any solution. When I start the deck from cold, the arm goes down normally, but when it is warm it lowers too fast. That's why I went to using a Beogram 4000 actually, because I feared for my expensive Soundsmith!

This seems to be a common issue alright.

 

Thank you both for your replies, and it is at least slightly reassuring to know that I'm not alone. 

Still,  I can't really believe this is the correct mode of operation for lowering the arm.  Looking through various threads on the Forum, 'Peter', from whom I bought the Beogram and who knows a lot about the earlier tangentials,  has written when answering another query,  

'When the solenoid engages, the arm drops in a damped fashion'. 

Well, it certainly doesn't appear to be doing that.  It is definitely much faster than my old BG 4004.

Cleve

Hi Cleviebaby, I am (as you might have seen) a recent newcomer to this series of record players but that hasn't stopped my from pulling my 99% function 8000 apart already :)

One of the things I was eager to see is how the solenoid system worked compared to earlier models, and it is indeed different!

The solenoid actually has more in common with a moving coil of a galvo or similar in this model and the damping is actually controlled electronically! There is a little circuit that consists of an opamp and a couple of transistors, and it is the opamp that produces a ramped voltage to coil via a transistor. So your first port of call would be to check around this circuit, perhaps in particular at C9 but also look for dry joints cos mine had quite a few! Just need to clean the mute relay contacts (the only fault!) and waiting for a belt off Martin now!

Must say I love this deck some say it is under engineered compared to the earlier series I personally think it is a damn good compromise! It has certainly gone up in my estimations!

I remember it being faster than the 4000 but not uncontrolled. Maybe my house is colder!

Step1:

The solenoid actually has more in common with a moving coil of a galvo or similar in this model and the damping is actually controlled electronically!

Thanks for that, and to evryone else for their helpgul comments.  Having now had a look at Tim Jarman's piece on the deck on 'Beocentral', he also refers to the electronic operation of the damping.   I should have realised that with this deck everything is controlled electronically!  The problem for me, as always, is my lack of understanding of electronics (I dropped Physics as a subject at school as soon as I could) and my complete ineptitude with a soldering iron.    

Having looked closely at the arm's working, my perception is that the cartridge is riding very much closer to the surface of the record than it should - perhaps just 1mm, and having played a slightly warped record, the stylus guard is coming into momentary contact with the record surface.  I'm wondering if the tube of the MMC2 is starting to distort under the regular, relatively high impact of dropping onto the record with limited or no damping. 

I see another trip up the A303/M3 on the horizon. 

There is another, more fundamental issue here. though.  The problem for me, as always, is my lack of understanding of electronics (I dropped Physics as a subject at school as soon as I could) and my complete ineptitude with a soldering iron.  The danger with this sort of self-deprecatory comment and the thinking behind it is that I convince myself that resolving these sorts of practical issues is beyond me.  However, with a real love of vintage B&O, making these sort of repairs and adjustments really goes with the territory.  I really do need to learn how to do these things, and I know from many Beoworlders' comments on this site how satisfying that can be.  Is there a 'Soldering for Dummies' book?

Cleve  

Cleve

 

 

Cleviebaby:

Is there a 'Soldering for Dummies' book?

There is a lot on the net, just google it, read the theory, but more important, get an iron and solder and find an old radio or something to train on.

Its simple when you get the hang of it and very fast you will crave for difficault jobs

I use these tools

 

It's hard to say if the tonearm is actually lowering too fast without actually seeing it.
The damping is electronically controlled, it's more or less all down to simple RC-circuits and it can
be adjusted by changing component values.

Has the old capacitors been replaced ?

The low riding of the cartridge points toward a soon failing cantilever suspension, not uncommon unfortunately.

Martin

Hi,

How are you Martin?

Well even after a full refurbishment of the circuit (yes, even that cap inside the processor box!) the damping problem was never solved. The RC network you refer to was also envisaged. Raising the 1μF cap to 2.2μF restored correct lowering (a bit too long even, I'd say one sec) but the muting relay never triggered.

Any ideas?

Cleve's deck has had the capacitors changed in the past.  It has been serviced both by B&O and TJ.

Peter :

Cleve's deck has had the capacitors changed in the past.  It has been serviced both by B&O and TJ.

Peter,

I know from previous threads and from email correspondence with you when I bought the deck that it had been serviced regularly and most recently by TJ - it was one of the reasons why I bought it.  However, I guess that service was a couple of years ago now and the ageing process applies to turntables as much as to humans.   It is one of the downsides of running old equipment and you have to factor in these things when you decide to go down that road.

I fully take on board Soren's advice about practicing your skills on a bit of old electronics, but I don't think playing with a BG 8002 is the best starting point for a complete electronics novice like me.  

Thanks to everyone for their advice - at least I now know what is probably wrong.  I think, given Martin's comments, it would certainly make sense not to completely wreck the MMC2 by using the deck until I've sorted the problem.  As a sufferer from the Beovirus, the 8002 isn't my only deck, so I can still play records. 

Cleve

    

 

You would appear to have picked the wrong cartridge! I believe you sent one back to Lee - I imagine that was the one Axel had just rebuilt!

Peter :

You would appear to have picked the wrong cartridge! I believe you sent one back to Lee - I imagine that was the one Axel had just rebuilt!

I sent Lee the one in Axel's small plastic case on the grounds that this was the one from your BG7000 that Lee was selling as part of your 7000 system.  There has been no evidence that the one in the 8002 was on the way out - it has been tracking well and with no signs of distortion.  However, it looks like it might be suffering some cantilever damage now!

 

 

Maybe try lowering r61 (assuming the 2u2 is still in place) slightly Jacqes? The muting circuit is controlled from the output of this section of the opamp and I would suggest the final charging of the capcitor slowed down sufficiantly that perhaps the mute circuit would have 'activated' sometime later than you would have been prepared to wait.

You may even have to adjust one of the resistors in the mute circuit, for instance slightly increase r54...?

I have to admit now that the damping on mine is not as smooth as the earlier decks but looks ok to me. Certainly consistant, but possibly a needless threat to aging cartridge suspension! I might investigate this myself :). Would be interesting to see if Martin has more to say on the subject!

Both a resistor and a capacitor can change its value over time so
we cannot rule out the need for replacing a component but check that the solenoid moves freely first.
If there is some kind of blockage, dust or the likes, the solenoid will not move freely enough to precisely
follow the DC slope.
If it binds near the beginning of its travel  where the voltage is still rather low (read: until the magnetic
force is strong enough to pull it passed the blockage), it can cause the symptom you have of sudden lowering.
A scope across the solenoid would help monitor what's going on. A multimeter may also be sufficient.

If all that looks fine, I would check the values of that RC circuit and eventually replace the OPamp, the
resistor or the capacitor.
A slightly larger resistor or capacitor would slow things down a bit. Obviously, it needs to be completely
lowered when the muting relay releases the output signals.

Martin

Thanks to Martin and Jacques for this insight into the arm lowering process on the BG8002.  It really demonstrates that I should have paid more attention to my Physics teacher. 

When I was at school (many, many years ago), at the age of 14 I had to make a choice between continuing to study either Physics or History - I don't need to tell you which choice I made. 

Cleve

 

Hi,

I've dismantled everything, the solenoid works fine, it is totally free in its translation, with no play. 

I don't see anything preventing the mechanism to run correctly.

The electronics have ben checked, they work just fine, and components have kept their values. 

And yet. The solenoid has a hiccup half way out, which I can't reproduce by hand. It isn't arm-related, since with the arm manually kept up it happens too. I've seen several other Beograms, 6006, 8000 and 8002 with the same problem.

A solution has yet to be found then. Oh well, let's wait for Martin to have one with this fault to repair!

I suppose the subchassis is merely standing on the bottom plate now.
Is the solenoid thing rubbing on something ? Try lifting the subchassis away
from the bottom plate a bit.

Martin

Hello Martin,

No it doesn't rub on anything. Its translation is free when I push or pull it by hand. Anyway, it is fully enclosed in its own housing.

I must be stupid or something but that one makes me mad! Earlier on the arm was in bits and pieces, now re-assembled and better aligned than before. The problem remains. When monitoring the coil voltage it appears to be growing normally.

What do you mean by hiccup? If I take a hickup to mean the arm seems to get momentarily stuck, could your coil (only when energized), be slightly moving off center and catching or rubbing?

I don't know.

It is very free to move and has no play.

Maybe the plastic part which pushed the lever is worn. Nothing I can see, but the 6006 has the same problem!