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Beogram 3000 motor

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scorron
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scorron posted on Thu, Sep 5 2019 2:17 PM

I recently acquired a Beogram 3000 (type 5228, built in 1974) with a motor that barely turned. Using instructions from this forum, I disassembled, cleaned, reoiled and the motor turned normal speed. In fact, it seemed to work perfectly for a few weeks, and now it is having speed problems again. I've read just about everything posted on the subject online, on this forum and others. Has anybody solved the motor problems that plagued these turntables? 

I ordered a rebuilt SP12 (not cheap) and now I don't even know if the turntable will be usable. I certainly can't enjoy listening to it with the speed jumping around. 

Before anybody asks, the belt is new, the idler rubber soft, all parts have been cleaned and reoiled/greased, switches cleaned with 1000 grit sandpaper. 

 

Thanks in advance,

Sean

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Dillen
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Dillen replied on Tue, Sep 10 2019 9:06 PM

It's not a question of viscosity.
It's a question of additives.

I see no mentioning of any statements from B&O regarding bad motors, never heard of any myself, it's not in my B&O tech notes collection or
any of the BoMark pages and I never experienced any problems myself during the 70s and 80s.
Not in Beogram 3000, not in any other deck, until oil started to dry out or wear away across the range.
My experience is, that sewing machine oil is good for sewing machines and of no use in sintered bronze bearings.

I'm not sure how long Vinylengine has been around or how much experience the mentioned member has - though it seems on the same page he is also receiving advice on how to do the bearings.

You are free to disagree.
You may also sit with more experience in these matters than my 44 years of collecting, repairing and restoring B&O audio products, but I know what I have been doing hundreds of times and what works every time for me - and I have also done 60Hz units sent to me from the States.

Any Beogram 3000 motor you'lll find today will need servicing.
I have given you my best advice, it seems you insist on trying something different.
I have nothing more to add.

Martin

scorron
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I used this oil: https://www.schaefferoil.com/moly-spindle-oil.html  Does it look like it has the appropriate additives?  I obtained a small quantity of the oil from a sewing machine repair shop. They find it has the qualities they need for long term operation and lubrication of the electric motors.

I appreciate your advice and followed it exactly. Thank you. 

solderon29
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There was indeed a problem with these motors back in the 'seventies when the product was still current,and the bearings were unlikely to have dried out in only a year or so?

One of the "urban legends" was that the motors were designed for 220v use,and so were slightly over run with the Uk power supply at 240v,making the coils overheat and eventually become "tired"This also seemed to happen with some Thorens decks that used similar induction motors.That argument doesn't hold of course for USA models running at 110v,where the motor coils are switched into parallel rather than into series,as with European spec?

We used to measure the cold resistance of the motor coils before proceeding with a repair,just in case this had happened,so as to save wasted time stripping down the motor,and getting a"bouncing" repair later,with attendant stroppy customer!

The motor's were made by Bogen for B&O,and they were/are jolly good when working properly too.

If a re-lubricated motor performs correctly at the right speed,but then gradually reverts to type(slow),then it suggests that the re-lubricating need's extra attention as Martin and other's have suggested.

If it's consistently slow though,it seems as though you have a "bad 'un",and will need to investigate the coils.A member here did have some success rewinding the coils,so it might be worth searching in the archive.

Do you have another Beogram of a similar type,that you could compare motor winding' s with?

I may have a note somewhere of coil readings,I'll have a search,but I may be a "while".

Regards,

Nick

scorron
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Thanks, Nick! I actually have the reverse problem: motor performs at a near-normal speed as soon as it is turned on, but then speeds up over the next 20 - 30 minutes. I can adjust the speed to 33 RPM when cold, but by the time the turntable has run for a while, it is running quite fast, according to the strobe, anyway. 

I will check the coil resistance. I'm not opposed to rewinding a motor, if I must. Appreciate the perspective. 

The fellow on Vinyl Engine is of the opinion that it is a rotor problem, and has performed some experiments which seem to suggest that, but any avenue is worth pursuing. 

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