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
Hi all,
I am new to this forum, and my two questions here are concerning my Beogram 4000, which is in a very good condition, exept for the tone arm that needs to be replaced by a new (old) one.
The type of arm is the ”difficult one” with five extremely thin leads coming out of the posterior part of the arm. The leads are meant to continue in several zig-zags down through the very narrow system of passages in the arm slide to finally come out underneath it all - to be soldered on to a small circuit there.
Q1: Does anyone know if it is possible to grip all five leads as a group - with a piece of for instance thin copper wire, inserted from behind through the narrow passages, and thus draw the thin tonearm leads downwards through the slides tubular system to be soldered there?
Q2: To be able to measure my tonearm's wireing and identify them, the leads will have to somehow be unblocked and behave like the pickup just has been lowered on to a record - and so is initiating opening for communication.
How do I do that?
I guess desoldering the thin wires from the small circuit board at the bottom while measuring, will solve this problem, but:
Is there a better way?
As I have never performed this kind of operation before, any advice will be very much appreciated!
Thanks!
Best Regards.
---
Rem: As of now I have disassembled the tonearm slide and separated it, positioning it upside-down ready for soldering. But I have not taken the whole slide-package apart - I hope I don't have to.
Rem2: I do have both the User's Manual and the Service Manual. But unfortunately that doesn't solve the problems. At least not for an amateur like myself.
Welcome!
Well what happened to the old arm anyway?
Methinks it was destroyed during transport because the platter was still in place, wasn't it?
Jacques
Hi Jacques!
Thanks for welcoming - the old arm lost communication with the world around it - the whole turntable lost its voice so to speak. I think because of too much changing of styluses - not least by myself, I'm afraid - so it ended up with this tiny little plastic-thing holding the contacts and going into the stylus-head and holding it - it broke off. Seems like the material had "tired out". One never knows how the machine was treated by the former owners. So... I really don't understand it - but it happened under change of stylus - a change that I performed myself - with caution - I thought.
:)
Ah yes. This dreaded problem is well-documented. Even Tim Jarman talks about it in his Hifi News article (June 2014!).
Now there is no particular problem with the thin wires, they are sturdier than they look. My own Beogram 4000 was delivered to me with the carriage off its guides, and they had even resisted bad transport conditions - the French Post, which is saying something!
Q1: my piece of advice is that you should solder the wires together at one extremity. Thus you'll be able to have them make their way through.
Q2: the cartridge tags are indeed identified in the SM (6-10) so you needn't test from them from inside the arm at all!
Thanks for your ideas, Jacques!
Q1: I will certainly give this soldering solution some serious thoughts. Btw: Do you clean the insulation off the wires before soldering - or does it get burned off by itself?
About Q2. I guess I got my thinking mixed up a bit: When I mount my new (old) arm, the leads are free and can be identified by measuring - no problem. I'm afraid that I mixed this up with my wish to measure the existing defective arm (still sitting there) - just to make sure that my diagnostics on the silence of the Beogram 4000 was plausible - and that no other problem is present there. It would be nice to solve any problems while I have it all open for inspection. But you are of course right: Stripped down to simply adding the new (old) tonearm, there should be no real lead identification problem. Mea culpa!
My new (old) tonearm should arrive today, and if it has survived the Post "service" of Denmark and Sweden - apparently rather similar to the French model - I shall install it directly. In case of new mysteries popping up, I'll be back for further assistance - thank you very much for your time so far!
Q1: set your iron on 400 degrees and the insulating varnish will melt.
Thanks for this advise, Jacques!
My new tonearm has arrived - seems to be unharmed.
But: This new arm has four upper contacts for the cartridge just like the old one - but two (2) lower contacts, whereas my old one had just one (1) lower contact. There are just five leads going from the socket and backwards through the arm, not six. This was a surprise. Why would the outer noise protection contact be divided into two? Is this for another model of cartridge perhaps - mine is the MMC 4000 and the MMC 20EN - both have one lower socket - which looks like it is a bit smaller in width than the two new contacts (or divided one) put together. Any suggestions? What do I do next?
:(
You've probably got a later one from a 4002 or 4004. Have you checked the corresponding service manuals?
Guess you are right. So close, yet so far.
Back to square 1. Must think.
Thanks anyway for your help this far.
:
I hear they can be adapted. Perhaps a visit on the archived forum would return a few interesting posts regarding this issue.
Wonderful! I shall most certainly explore this!
Thx!
This is my new tonearm. I have been checking around to get an explanation: Why does it have two lower front teeth, when the old tonearm had only one? I have not been able to verify any ideas of some possible 4-channel model. And both the BG4002 and 4004 are using a cartridge like MMC-3000 or similar - all with one lower socket. I couldn't find a cartridge by common search, that has two sockets in its lower part. A closer comparison looks like this:
It looks like the upper 4 teeth of the newer tonearm should fit in the top socket of the cartridge - but the lower 2 contacts do not fit directly into the lower socket.
Does anyone know what would happen if one combined the 2 lower contacts to one, and made it fit in width? What is inside? There should only be one shield since I have no 4 channels at all. So I have 2 channels of stream and put them into the cartridge which is 2 channels also. From there, these 5 tiny thin leads transfer the signals, and both of the shield contacts on the arm - if combined - should lead to one (1) shield. Is this right? The numbering of the 5 thin leads must be identified by measuring them (after the lacquer-insulation has melted/been burned away) - and the rest should be soldering the thin leads to the correct contact under the carriage. I think. Or?
I am guessing a lot here, which I don't like. Does anyone know?
Maybe it would do the trick just to squeeze the two lower teeth together? Have they been closer in an earlier life? They look a kind of displaced, I think. Will they break off?
Anyone?
Had the same problem with my Beogram 4000 tonearm as documented here
http://archivedforum2.beoworld.org/forums/t/11046.aspx
My replacement arm came from another 4000 but was still different.
My adaptation is working well, just had to increase the VTF on the dial as the new arm was a bit lighter.
jeules0: Had the same problem with my Beogram 4000 tonearm as documented here http://archivedforum2.beoworld.org/forums/t/11046.aspx My replacement arm came from another 4000 but was still different. My adaptation is working well, just had to increase the VTF on the dial as the new arm was a bit lighter.
Just realised the link is not working.
The post is entitled 'MMC rebuilt then drama fitting it'
Hi jeules0
Thank you. Sounds interesting. Would really like to read your "drama". But unfortunately I can't find your post. Could you please produce a working link?
Very pleased with the new cantilever and Shibata retip on my MMC4000 by Axel Shuerholz in Germany.
Posted it off from the UK and it was back in just over 2 weeks: excellent service!
The nightmare began when I snapped the plastic locating stub on the end of the tonearm on my Beogram 4000 trying to remove the MMC 20EN that I'd been using.
After a few choice words, I thought never mind I've got a spare on the parts-only deck I bought recently. I removed it from the donor deck easily enough after undoing a screw, sliding it off and unsoldering the wires on the connector board
I then removed the damaged one, only to find that this one had a completely different connector: it simply slid off with no wires visible, just brass strips on a slide-fit connector board.
To cut a long story short, I managed to make one good arm by wrecking the broken arm to extract the internal slide connection, and then soldering the wires from the good arm to it. I then made the connection and re-fitted the arm
MMC 4000 was then carefully fitted, VTF adjusted and now sounds great. Phew!
Thank you! Very interesting!
Your problem started when the "stub" broke off after having used a MMC20EN and so did mine.
I had no problems demounting my MMC4000 and neither did you, it seems. I wonder if there is a difference in the design of the main (upper) socket between the two? When/if I ever succeed in getting this new arm working, I will certainly use my MMC4000. It always felt as it fitted better when placed on the arm.
Of course, it could be a coincidence. But why risk it?
Thanks for letting me read this!
Continuation.
One step closer to a solution. I have "determined" that the two lower contacts on my new tonearm in fact must be one. It seems to be divided in two branches only. When forced together these two branches become a small "spring-system", pressing itself outwards on both sides, thus helping to establish a better retention than a more passive lower contact.
The two branches were rather heavily deformed too - someone has been using force on pressing a badly fitting cartridge against them. So they pointed at different directions. I have tried to - cautiously - bring them back to normal. Just that I don't realy know what normal is for these branches. Which has resulted in this placement of the cartridge - please see picture. A step forwards - but not very pretty. It needs a last adjustment - if I knew how.
I should like to know how these lower contacts are supposed to be looking - if anyone has the possibility of showing me on a photograph?
As of right now, the tonearm + the MMC4000 looks like this, when mounted:
Not satisfactory! But soon there - I hope.
Anyone having a photograph of these lower contacts - as they should look?
Solved!
The culprit was bad gluing of the whole black plastic contact package inside the arm. The contact package had moved forwards leveling the arms front opening. It should be sitting ½ mm under the edge, inside the arm's front opening. Pushed it ½ mm backwards. Case solved!
Well done! It' a nice feeling when you finally succeed!
//Bo.A long list...
Yes, that looks better :-)
Have you got it up and running?
Chris
Well done, well done! All you needed was a little incentive. You figured it out all by yourself, which is an essential learning step.
I wouldn't be too happy with the seller though. Unless the arm was given away to you of course!
Thanks Bo, Chris and Jacques.
Yes, Today is Ta-da!
No, I haven't got it up and running yet. Hope I will soon. Next step is to figure out how to draw these microscopic leads through the slide internals in a good manner. So I don't exactly feel any serious reason for arrogance right now. And about the seller I'm just gratefull that a tonearm existed for my table at all - as they are very hard to come by these days. And one can't hold it against the seller, I think, that B&O, flimsy as it seems, changed the lay-out of the Bg4000 tonearm three times - after all this was their first tangential experiments and experiences.
The real problem was that I unfortunately didn't know this before now.
Time to proceed...I shall be reporting back as soon as it all plays...and in case of upcoming mysteries, earlier.
Thank you!
Hi, so is there actually a problem with the wiring that stops you connecting your 'new' arm to it?
Hi Chris,
no I don't think there actually is. But since this is my first time doing this, I feel somewhat uncertain and I am planning everything carefully in detail. No stress. At the same time I am documenting each step I take in text and photography. Takes time too. But who knows, maybe it can lead to a tut some day. A tut for novices - written by one.
As Henry Ford said, 'If it ain't bust don't fix it!' Or something like that.
i took one look at the wiring as I was going to do a complete swap, but thought, "On second thoughts, I think I'll leave it alone." :-)
I've had the Bg4000 up and running now. It played. But my left stereo-channel was silent. And still is.
The wiring became complicated because of the mix of tonearm-models. The donor arm contains only thin copper wire leads, without any color coding. And the receptor arm fragment is a model containing a small circuit on which the leads are soldered. I did so following the diagram for another cartridge-type, trying to translate the diagram to the MMC4000-type. As there was no colored leads in the donor arm, I had to reconstruct the colors from the SM information. And I have been following Menahem's article on altering the wiring in a reversely/wrongly wired arm in a Bg4000 reconditioning.
I followed this diagrammatic sketch:
- and more or less guessed that the wiring of the MMC4000 probably should be like my extra sketching. The small color picture at the right has been borrowed from Menahems article on this forum. I hope that's ok.
I have measured the whole thing and found that the white wire from the connector no3 which I see as analogue to L unfortunately has a short to chassis. And I can't find where it is. So the channel is silent. The right channel is working ok.
The muting relay is working physically but I have a little humming and no muting between start and when the stylus contacts the record. When the record is being played there is no humming - it sounds normal - but only in the right channel just now of course.
When measuring the leads I used a small piece of paper as insulation in the relay.
Any ideas for attacking this problem will be very much appreciated.
Had an idea that I would try to simplify the sketch of the Beogram 4000's tonearm wiring. To make things easier. This jigsaw puzzle is step one on that road:
Will this play?
Yes, it plays.
Everything works fine now - the sketch works, I hope it can be of help for some other novice fighting a BG4000 tonearm problem.
Problem solved, case dismissed.
Good work, good drawing, a keeper, thank you
Collecting Vintage B&O is not a hobby, its a lifestyle.
thank you for the drawing of the cartridge leads, it was very helpful to me :-)
I need another donor 400x arm as well, have been looking for ages, and my Beogram 4000 is just sat in the corner looking sad - as I am :-(
Is the arm broken or missing?....Or is the problem just that the cartridge mounting tab is broken? I have repaired two Beogram 4000 tonearms that had broken cartridge mounts. The first one was done by stealing a good cartridge mount from a Beogram 4004 donor turntable. The second one was repaired by getting a new, 3D printed cartridge mount from forum member Beolover. Both turntables are still working great. I use them quite frequently.
-sonavor