MMC20 Genetic manipulations…

matador

BronzeModerator

2424 posts

Posted June 21, 2022 at 09:45 GMT ? Edited May 11, 2024 at 08:35 GMT

Hi guys, ******************************************************************* WARNING: THIS TOPIC MAY BE SHOCKING FOR SOME MEMBERS Please accept apologies if this is the case. ******************************************************************* Well that being said, I had that MMC20EN with missing cantilever that came loose inside a Beogram 4002 in addition to the one fitted to the deck. I thought to have it restored but when you're on a budget, cartridge repair is not an easy journey: prices, terms, possibilities of repair or not and did I already said "prices"? Anyway, one day after further inspection, I discovered the cantilever was not missing, it was broken. And it was hollow! So first thing was to find something to fill that hole. I tried:

Cactus needle -> too thick.
Sewing needle -> too thick.
Copper wire -> too soft.

I finally use a metal strand from a wire brush, it was perfect in diameter (0,25mm). Next I needed to have a stone on the other end. All this being very uncertain I didn't want to spend a lot so I bought chinese bulk saphirs: 3 for 6€. They arrive like one week after: Next step was to cut the cantilever at the right length with an cutter and insert the strand in it with a drop of glue: Cut the strand and insert it the remains of the old cantilever: Right now it is not glued and the original cartridge has remain unchanged. but the friction is enough to be able to try it like that. And… … Believe it or not, it works! I can ear bass, treble, high, no rumble or something, no distortion at least at average listening levels. Output level is similar to my MMC20S. I tried it on a quite old and used record but, to me, the concept is working. Now I need to decide if I go along and glue the needle after refining the azimut or if I stop the experiment here to maybe have it restored one day. I've got two MMC20E, one in use and the other one NOS as backup. I also understand, by now the suspensions must all be dead or at least worn. But a spare cartridge just to check a deck is working is always useful. And not being a so serious listener it may even work for background music, In all case better than a non working one. Also it makes me think that with the right tools and dexterity, a lot of things can be made. Cheers!

Location: Paris France

YannChris

Gold

1043 posts

Posted June 21, 2022 at 11:36 GMT

#692466

Thumbs up!

Location: Brittany, France

My B&O Icons:

Infected at the age of 13 by a BG 4000 in Dad's Hifi shop.

GE

geoffmartin

Bronze

112 posts

Posted June 23, 2022 at 14:54 GMT

#692502

Too bad you're in France and not next door. I'd be interested to measure this to see how good/bad it turned out! On the other hand, I have some broken cartridges lying around. I might just try to duplicate your results by making some franken-pickups of my own... :-) I'm curious about the "chinese bulk saphirs"... Cheers -geoff

PLEASE READ before sending me a Personal Message. If you have questions about or problems with B&O equipment, these should be directed through your dealer and/or B&O's Customer Service department. I cannot be a "short circuit", bypassing these communication channels. Thanks -geoff

matador

BronzeModerator

2424 posts

Posted June 23, 2022 at 16:32 GMT

#692504

Oh, God! I was expecting all sort of reactions but absolutly not your curiosity Mr Martin! To answer two quarters of it:

Not need to measure: Sapphires are at best spherical so, in my understanding, less good than any other shape. They're also softer so prone to wear quickly and therefore, damage the record (still after my google wisdom understanding). I don't even talk about parameters I don't master like stifness of the cantilever or anything like that (you may not be aware of, but there is a 20 pages "technical sound guide" about beograms, I'm not sure I've shotcuted with a 10€ trick!).
The Chinese bulk sapphires are replacement parts for low cost record players that all use the same cheap needle. You find them on the bay, here in France "à la FNAC" and maybe in every similar tech store around the world. A little reading will teach anyone they share nothing with the lowest even not B&O tip.

And to answer the last bit:

I'm still happy because despite all the above it did still work "not outrageously bad". It shows this is possible and be done better with better skills or care or money. For instance by replacing the cheap sapphire with a diamond or using a better strand or whatever else. Maybe just with more steady hands and a better magnification device.

One midway solution would be to be able to use that sapphire or any other tip if it could be glued strong but unglued easily. In any case, I know this will be like a slap in the face of any well serviced Beogram, but experiments need to start somewhere! Regards. M.

Location: Paris France

chartz

Bronze

240 posts

Posted June 24, 2022 at 16:25 GMT ? Edited June 24, 2022 at 16:28 GMT

#692518

Hi, Good idea. Done that, been there! The telescopic repair, I mean. The MMC is worth a better stylus of course. I have just repaired a DL103 with broken cantilever (keeping the original broken cantilever). I used a tiny medical needle, and believe it or not, the cartridge sings perfectly. The SP series are easy to do because they have a spigot on which you can attach the alu tube, with moderate force. No need for glue. I think the MMC4000 has the spigot too.

Jacques

matador

BronzeModerator

2424 posts

Posted June 24, 2022 at 17:35 GMT

#692520

Location: Paris France

GE

geoffmartin

Bronze

112 posts

Posted June 25, 2022 at 15:50 GMT ? Edited June 25, 2022 at 15:50 GMT

#692537

Hi again, No need to make excuses... I'm genuinely curious! I'm currently in the process of turning two sick 42VFs into one healthy one - but I don't have many pickups with the cantilever still attached (the end result will have the 20º tonearm - not the later 15º version, and the SP1-2 pickups are hard to find in good condition...) Given the way I'll be using this turntable (mostly with my 78 RPM disks) a DIY pickup rebuild would not be crazy. I'll have a look around for the sapphires - maybe I'll have to call in a favour from an audio geek friend in Paris to look around the next time he's at FNAC if I can't find my own around here in the fields of Jutland... :D Thanks for the inspiration! Nice work, in my opinion! Cheers -geoff

PLEASE READ before sending me a Personal Message. If you have questions about or problems with B&O equipment, these should be directed through your dealer and/or B&O's Customer Service department. I cannot be a "short circuit", bypassing these communication channels. Thanks -geoff

GE

geoffmartin

Bronze

112 posts

Posted June 25, 2022 at 17:02 GMT ? Edited June 26, 2022 at 10:54 GMT

#692541

I forgot to add... > you may not be aware of, but there is a 20 pages “technical sound guide” about beograms I am aware of it... I wrote it. :-) EDIT: I didn't realise it was a joke. I'm a bit thick this weekend, apparently. Sorry... :-) Cheers -geoff

PLEASE READ before sending me a Personal Message. If you have questions about or problems with B&O equipment, these should be directed through your dealer and/or B&O's Customer Service department. I cannot be a "short circuit", bypassing these communication channels. Thanks -geoff

matador

BronzeModerator

2424 posts

Posted June 25, 2022 at 19:36 GMT

#692543

Location: Paris France

GE

geoffmartin

Bronze

112 posts

Posted June 26, 2022 at 10:57 GMT

#692551

It's a good question - but I think that shellac (+ limestone) 78s are harder than PVC 33s. Also, the groove is MUCH wider, so there's plenty of room for error. Either way, it's worth a try. Thanks for the ebay link you sent. This will give me a new project once the days start getting shorter here in Denmark. Cheers -geoff

PLEASE READ before sending me a Personal Message. If you have questions about or problems with B&O equipment, these should be directed through your dealer and/or B&O's Customer Service department. I cannot be a "short circuit", bypassing these communication channels. Thanks -geoff

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