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Vinyl Asylum Welcome Licorice Pizza (LP) lovers! Setup guides and Vinyl FAQ. |
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Vinyl Asylum Welcome Licorice Pizza (LP) lovers! Setup guides and Vinyl FAQ. |
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In Reply to: Re: Thorens TD-124 speed issue...too fast posted by aktan on September 11, 2006 at 02:12:25:
In the main bearing housing there are two sintered bronze sleeve bearings that support the main spindle. Sintered bronze is made from very small bits of bronze that are pressed together under high pressure. The motor has similar bearings for the stator.They act like sponges and absorb oil. Then as the spindle turns it heats the bearings and the oil flows back out providing a film of lubricant to keep the platter spinning smoothly.
So far, so good.
Except in our case the 45 year old mineral based oils that Thorens used have turned to varnish - a sticky sludge that acts like glue in the bearings. The bearings are packed full of it. Simply flushing the main bearing housing did not even touch this reservoir of crud.
As the platter turns it heats the bearings and the varnish displaces the nice clean oil you put in the housing. The platter slows down - until you clean it out again. Then the process repeats again.
The only way to fix this problem is to flush the sleeve bearings free of the varnish. Simple solvents won't work because the sludge is embedded in 1000's of microscopic pores in the bearings. All that solvents do is remove the top layer.
You have to heat the bearings to force out the sludge, clean it off, and let the bearings cool in a bath of clean oil to pull clean oil back into the pores (if you skip this step you've filled the pores with solvent - a terrible lubricant).
It took 7 heating/cooling cycles for the black gunk to stop coming out of my bearings and I know I still didn't get it all. But it made a huge improvement anyway.
Heres one approach (look in the archives for others):
Disassemble the main bearing housing and place on some foil. Heat your oven to about 150 degrees and put the housing in for 20 minutes. Remove and flush with solvent (some use mineral spirits or butane, I used isopropyl alcohol). You will get lots of greenish black gook out of the bearings. Repeat until the solvent flush comes out clean.
Then place the housing in a container full of a good synthetic oil (I use Mobil 1) and put the whole thing back in the oven for an hour. This will drive out most of the solvents, plus a bit more sludge.
Remove from the oven and let it cool while in the oil bath - this will allow the bearings to soak up the clean oil. If I were doing it again I'd heat/cool the main housing a few times in the oil bath since even more sludge came out after a single oil bath heat/cool cycle. Messing around with 150 degree oil is a pain so beware...
Now you have reasonably clean sleeve bearings and it will take a long time for the sludge to slow things down again - mine is somewhat slower after a year but is still within adjustment range.
Do this process for the motor bearings too and you'll be amazed at how smoothly your TD operates and how quickly it comes up to speed and stabilizes.
Good luck,
Pete
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Follow Ups
- Not the ball bearing - you have dirty sleeve bearings - Pete Fowler 07:35:22 09/11/06 (0)
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