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Hello all,
I'm restoring an old BeoGram 1203 left to me by my late grandparents and alas the motor is almost unusably slow - it takes around 15 minutes to get up to speed.
Does anybody have any knowledge of the repaire/replacement process for this part? I can't imagine it's too readily available given this model ceased production in 1976.
Thanks
Jon
Hi
You need to Clean and re-oil the bearings under vacuum.
Keith.
The engine has to be removed out of the player, and fully taken apart, pulley and idlerwheel holder to be removed first. Note the 3 brass parts, 1 is shorter than the other 2.
Take the upper platter of the engine, leave the anchor in the engine, and use the plastic back of a screwdriver to "hammer"it down so that the bottom leaves the engine. Then clean the both bearings with reduced earcleaning sticks. Grease it with very tin oil , mount the engine without fastening the 3 screws, and place 2 thin aluminium blades in the lowerside of the engine, in the gap between the anchor and the engine.Note the 3 brass parts!!
The blades can be obtained by clipping them from an aluminium luxaflex rollercurtain.
Then fasten the screws, take out the alu parts and the engine should run ok. Good luck. Beovintage
Just oiling it will only make it run for a short time, from a few hours to a few months. It will soon have pressed the new oil away and the motor will run slow again - or not at all.The oil sits inside the pores in the brass material.The oil is infused into the pores under vacuum and is sucked out when the motor is running by capillary action.
An oil with the right additives will have to be used. Originally SAE30 was used.
Beolover shows how to do it here, though with Beogram 4002, but the principle is the same.
https://beolover.blogspot.com/2018/06/beogram-4002-dc-motor-restoration-spark-snubbers.html
I do it the same way, though I like to clean out the remains of the dried oil etc. from the pores first using an acetone bath.The felt reservoirs (not in Beogram 4002) will also need cleaning and a couple of drops of oil to replenish the bearings as the oil is used up.
Do a Google search for Oilite bearings. It's interesting reading.
Martin
The engine can be repaired but you have to know how. It must be taken out of the player, , and dismanteled all the way. Both bearings must be cleaned and polished (a bit) , that's it. Beovintage
That's what you could do to a steel-bearing, but I would never recommend it to sinter-bronze.
Sinter-bronze is a very delicate and soft material, - you can easily deform it by handling it carelessly, even with just your finger-power, and you can scratch it with a nail.
When the motor is running, there is no metal-metal contact between the spindle and the bearings. The spindle runs in a very thin film of oil, pulled from the pores in the bearing metal by capillary action from the rotation of the spindle itself.
That's also why the bearings practially won't ever wear down and more or less last forever - or at least as long as oil is pulled from inside the bearing and replenished from the reservoir felt washer.
If you grind or polish the bearing, you will smear out the material and clog up the pores, oil will not be sucked from the material, or only with difficulty, because the capillary action won't work.
The same can happen if you force a motor with sinter-bronze bearings to run without oil. Bearings will be damaged from the metal-metal contact, which could be seen as a kind of polishing.
If you only add oil to the outside of the material, the motor will only run for as long as it takes for the oil to be pushed away, used up or evaporate.It won't be replenished as intended, so the motor will typically only run fine for a short time after which it will be back to starting slow andrunning rough (if at all).Depending on condition, oil type and use etc. this could be a matter of a few months, a couple of weeks or even as little as 24 hours.
Up to apprx 1/3 of the bearings weight is from the oil it contains.In other words, a freshly filled bearing can weigh up to 50% more than an empty bearing.
More reading about Oilite bearings;
https://en.wikipedia.org/wiki/Oilite
Hello. I quick Q. f the speed is just a little slow ,would honing away som brass from the bully do the trick? i.e. make it run faster? Erik fro Oslo