Vintage Products

Re: Tone arm needs extra weight

rayfenwick — Sun, 11 Dec 2011 17:51:19 GMT

Hi Dan

Yes, that's exactly right.

One thing I should perhaps mention, although it may be blindingly obvious, is that as these B&O cartridges don't have a removable stylus extreme care should always be taken in handling these Beocenters. Because there's no arm rest with a locking catch like many other turntables, and because the arm is so thin, huge damage can be done by moving one without taking proper precautions - that flip-down stylus guard may protect a little during dusting, but offers no protection to the stylus if a loose arm wanders across the platter or bashes into the deck itself. Similarly, counterweights will rip themselves off the arm and do untold damage (a mint-looking Beocenter arrived completely trashed - including the expensive MMC2 that was on it...) Always remove the MMC - even if you're just moving the Beocenter across the room or onto another shelf, just to be on the safe side. As for the counterweight, remove it and pack it separately if you're ever going to transport the Beocenter anywhere..

Finally, they're a great system with fabulous retro looks, and a sound quality that surprises many. Unfortunately, when they come up for sale they are often damaged as stated above, or end up being bought solely for the MMC that's on them, so someone can put it into their later tangential - especially if it's one of the higher-end MMCs... so they're becoming increasingly rare. Twinned with a Beogram CDX CD player they make a superb system, and if you like that analogue sound, I can't recommend the partnership highly enough.

Re: Tone arm needs extra weight

DanP — Sun, 11 Dec 2011 16:17:12 GMT

Hi Rayfenwick,

Many thanks for all the information. I really appreciate it. I hope I can manage from here on.

Yes, I noticed that the counterweight has a screwdriver slot in its end. My guess is that the "tube" will come out when I turn the screw (in either direction). Then clean it and re-lubricate it before installing it back on the two rubber mounts and thereafter screw the black counterweight back in place. Finally, I callibrate the tone arm and the counterweight as Chris's instructions. Is this correct?

Also many thanks to Chris and mediabobny re Alex (http.//www.schalplattennadeln.de)

/Dan

Re: Tone arm needs extra weight

rayfenwick — Sun, 11 Dec 2011 13:23:35 GMT

Hi Dan

Good photos. It seems that I was incorrect in assuming that for some reason the arm per se wouldn't lower onto the record. It seems that mediabobny was correct, and it's failed stylus suspension causing the stylus to 'droop' out of the cartridge and making contact with the record before it should, and it is this that is preventing it operating correctly. The only way to solve this is either a repair or replacement MMC.

Don't worry about the counterweight coming off - it gives you an opportunity to clean the old lube from the rotating scale to ensure it can rotate fairly freely on the counterweight. The aforementioned 'tube' will come out of the counterweight (there's a screwdriver slot cut into the end of the tube) and everything should be cleaned and re lubricated before replacement. Replace the tube first (luckily you still have both rubber mounts - leave these where they are and slide the tube over the whole thing - the real PITA is if the end rubber gets stuck inside the tube, because it takes some getting out - ask me how I know.....) then the counterweight, and callibrate as per Chris's earlier instructions.

It looks a nice one that, and it will be good to get it all working properly. I have a reasonable condition 2-way remote control for the 7700 available if you fancy one....

Re: Tone arm needs extra weight

DanP — Sun, 11 Dec 2011 11:39:57 GMT

Thank you for all the information,

I hope these photos show more than i can explain.

To start with: This is my Beocenter 7700. The speakers are two s45-2. All in good condition.

The Problem:
This is the the cartridge with extra weight and before i lightly "tap" it.

This is after I have lightly "taped" the cartridge:

The "Cradle":

The counterweight was stuck... and this what happened today... yes it came lose. Is this good or bad?

Re: Tone arm needs extra weight

mediabobny — Sun, 11 Dec 2011 09:24:19 GMT

I've had the same problem. The arm lowers as it should but the stylus remains in its drooped, failed state. Press down on the tone arm and the stylus will 'pop' into its higher, correct position and play properly.

Re: Tone arm needs extra weight

rayfenwick — Sun, 11 Dec 2011 04:57:04 GMT

Hi mediabobny

I don't think it can be stylus suspension preventing the whole arm from 'dropping down' I'm wondering if the arm isn't correctly seated in the carrier (the grey cradle under the arm that lifts it). A photo would definitely help, DanP :)

Re: Tone arm needs extra weight

mediabobny — Sat, 10 Dec 2011 22:47:00 GMT

DanP:
Then with a light tap on the tone arm / needle with my finger it "popps" down and stays in this position thru out the whole record, it doesn't skip and the music sounds great (at least in my ears)

This is a classic symptom of a deteriorated stylus suspension - a very common problem with those old MMC cartridges. You'll either need to have it repaired (e.g. Axel) or obtain a replacement (e.g. Soundsmith). Or just keep pushing it down till it snaps into place. But it will fail completely sooner or later.

Re: Tone arm needs extra weight

rayfenwick — Sat, 10 Dec 2011 18:22:46 GMT

Hi Dan

The arm on these is quite an interesting design... the bit of the arm behind the pivot that the counterweight screws on to is actually not the same piece of metal as the rest of the arm - behind the pivot the arm thins dramatically, and the bit of arm that the counterweight goes onto is actually a separate tube, insulated sonically from the rest of the arm by 2 rubber bushes, one inside the rearmost tube, and the other just visible as that black line just behind the pivot point. I think what's happening is that the lube has dried on your assembly, so that when you try to turn the counterweight you're actually turning the rear of the arm on its rubber bushes. Same story as for why you can't turn the silver scale against the black weight.

I've done a quick drawing of the assembly. It's rough, but should give you an idea of how it's put together:

My assembly had the same problem, and I ended up having to rebuild it, as the 'tube' fell off the back of the arm because of bad packaging, and the rest was gummed up with old lubricant. The unfortunate thing is that I don't have the photos of the procedure anymore...maybe some fellow Beoworlder has a link to some..?

If you get stuck with it, I can take some photos of mine tomorrow - it's on a shelf and would require relocating to give me rear access, so I can't do it tonight...

Hope this helps

Re: Tone arm needs extra weight

DanP — Sat, 10 Dec 2011 17:49:01 GMT

Hi Rayfenwick,

Thank you for replaying so quickly.

This is my first B&O and I am quite an amateur in the world of mechanical techniques.
I bought my 7700 from a 86 year old person who had it from new (1986) but the last 8-10 years he had only used the radio. Maintenance-service has never been done on it. But he claims that the turntable worked fine until he stopped using it.

The issue is that when I try to turn the counterweight, the silvery thing with numbers on it on the tone arm, I can turn it, but when I let it go, it moves back to its original setting ( like it is spring-loaded ). No matter if I move it counter or clock wise.
When I hold the counterweight (the black part) and at the same time turn the silvery dial, then I can move it with some force to any numbers.
Could there be old dried up lubricant that needs to be cleaned out and replaced? Is it possible to take the counterweight apart and clean it?

When I adjust it to +-0, I suppose that the tone arm should be hanging free in a horizontal level. This is not the case, the needle always touches the record. When I try to play a record, there is always the issue that I need to add extra weight on the pick-up and to lightly tap it to stay in the track.

Also many thanks to Chris for the link to an earler thread "balance / zero your tone arm".

/Dan

Re: Tone arm needs extra weight

rayfenwick — Sat, 10 Dec 2011 10:19:21 GMT

Thanks Chris.

Re: Tone arm needs extra weight

Medogsfat — Sat, 10 Dec 2011 08:52:26 GMT

To zero/balance your tonearm look at THIS THREAD - it is for a Beogram RX but the method is exactly the same.

Chris.

Re: Tone arm needs extra weight

rayfenwick — Sat, 10 Dec 2011 07:55:33 GMT

Hi Dan

Welcome to Beoworld.

I have a 7700 in my living room that I rebuilt from parts from 3 others, so I know them pretty well.

This may be stating the obvious, and if so I apologise, but is the scale on the counterweight telling the truth? Get the arm to balance, and turn the counterweight scale to 0. Then adjust the whole assembly so it reads 1.2

If you know all about this business, then ignore the above. Perhaps a photo of the pivot assembly and the arm carrier that sits underneath might give me a clue - maybe something isn't quite seated right...

Hope this helps...

Tone arm needs extra weight

DanP — Sat, 10 Dec 2011 03:12:18 GMT

Hi, last week, I bought a Beocenter 7700 from 1986. This is also my first time writing in this forum. My Beocenter seems to be in very good condition except from one problem that I am hoping someone can help me with.

The problem: The pickup arm needs “extra” weight and also needs to be manually pressed down to work.

I have taped on a paperclip for some extra weight. It is still skipping. Then with a light tap on the tone arm / needle with my finger it "popps" down and stays in this position thru out the whole record, it doesn't skip and the music sounds great (at least in my ears)

The needle is sitting 3-4 mm over the LP (without any weight) before lowering down on to the record and then it is hopping/skipping (jumping).

The counter weight is turned to almost 1.5 It says in the manual it should be 1,2.

I am hoping for some advice,

Many thanks, Dan