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Old 25th February 2007, 05:09 PM   #1
ginsner is offline ginsner  Canada
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Default sony turntable bearing

I just got an older sony turntable (ps-2700) which belonged to my grandfather and by the looks of it is a pretty decent unit.
Its a belt drive with what looks like good damping all around and an adc cartridge.
The only problem is the spindle sinks into the bearing assembly causing the gear mechanism for the automatic functions to bind aswell as not allowing it to spin freely.
Before i try to fix it can anybody tell me about the bearing/bushing assembly? what to look for, what kind of grease to use, how it is constructed etc.
I am pretty excited as i might finally have a decent source for my quad stereo and B&W speakers.
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Old 1st March 2007, 10:08 PM   #2
kevinkr is offline kevinkr  United States
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The first thing to do is to look for a service manual for this table on eBay or elsewhere. (Possibly vinylengine will have it.)

Without knowing the details of its bearing construction it is hard to guess what might be wrong with the bearing. Perhaps it has a thrust plate or ball that is damaged or missing.

Proceed cautiously if you have to spend any money, it is not necessarily the case that this TT is worth your efforts to fix it. Should that not be the case an old Thorens TD-125, 150 or the much later TD-316 might be worth a look if your budget permits.
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Old 1st March 2007, 10:15 PM   #3
kevinkr is offline kevinkr  United States
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Link to manual on eBay:
http://cgi.ebay.com/Sony-PS-2700-Ser...QQcmdZViewItem
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Old 1st March 2007, 10:51 PM   #4
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Turntables like that usually have simple sintered-bronze bushings with most often small teflon thrust plates, Usually a thin film of light duty grease is applied to the spindle by the manufacturer to aid in quiet rotation. Tough this type of setup so typical of Japanese belt drivers looks simple and maybe cheesy, rest assured it's not bad. ( More on this later)

Check to make sure the thrust plate is not damaged or missing to reflect why your parts are interfering. The bushing is likely in A-OK shape as these are extremely long lived esp. if the grease was constant in the years of usage. Check the spindle to see if it is actually the right one for that table or if its is damaged or some how worn out, which is should not be if the lubrication was in good condition.

Onto the design, really these types of spindle set up from most Japanese tables worked well. I have a kick a$$ DIY table using a sintered- bronze bushing on a teflon thrust plate and a new made spindle from stainless steel. I have a platter and sub-plater setup that si betwen 10-15 lbs in weight and my simple setup runs very quietly and quite stable even though is a little top heavy.

My lubrication was done first by making sure the teflon thrust plate attached to the bushing housing was sealed up and cured. I then put in about 5-6 drops of bearing oil for light duty motors. I then on a custom made stainless steel shaft groove with a centre-groove smeared an even but not to heavy film of high-temp bearing grease. I thought the stiction of the grease at start up may be a concern but no problem the motor used pulls the platter up to speed so effortlessly using a thread drive that the spindle bearing setup is as I said dead quiet and quite stable.

Anyways my thoughts are as noted above, check your thrust plate for damage or missing, or the spindle supplied so that it is not the wrong one or somehow damaged too.
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Old 2nd March 2007, 10:22 AM   #5
owen is offline owen  United Kingdom
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The trust plate is held in by a circlip on the bottom of the bearing, and is likely to be nylon, or if you're lucky, Delrin.

The shaft is a high tolerance item, and the bearing material is indeed sintered bronze (I've had 3 'Ponys'). The bearing height may also be adjustable - as they are held in place using a thread on the bearing, and a large nut to hold it to the top plate.

WRT to modding. GO FOR IT. The motor isnt bad for an AC synchronous jobbie. The bearing will be more than ok. The automation is easy to strip out (and should be done asap).

Bitumin line the top plate, and expoxy metal ribbing to the underside - increases the stiffness and damping of the top plate, and is VITAL.

The platter will be a die cast aluminium effort that will ring like a bell. Strategic damping will again do wonders.

Replace the platter mat (I tried allsorts, silicon dots, drawer lining material (the green fuzzy stuff with a self adhesive back).

The arm will be the weak link. It will need rewiring - I used good in ear headphone cable to good effect, and the bearings will need to be adjusted (assuming your arm has adjustable bearings).

Gluing the headshell in place will work wonders, and replacing the counterweight stub rubber washer (that 'decouples' the bearing housing from the counterweight stub) should be replaced with a more solid material - there are nylon inserts around that will do the job nicely for pennies.

The final check will be on the motor mount - this is likely to be 3 soft rubber bushes, that sadly I've yet to work out how to replace without increasing motor noise (or completely rebuilding the table)

Have fun, you'll learn alot along the way


Owen
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