BIC 960 Platter Bearing Construction
BIC turntables from the 1970s were lubricated with a grease that dries out and turns solid with age. This happened to mine. While this problem is relatively easy to solve, if you do not understand the construction of the platter and bearings, you can easily do some serious damage. I know because I damaged my 960. This article will guide you in the correct procedure so you do not have to repeat my experience.The platter actually has two bearings. One is a sleeve bearing, in which the central tube of the platter casting fits over a steel spindle. The other is a ball-bearing assembly that supports the platter. The first photo shows the underside of the cast aluminum platter. Note the long tube in the center that forms the sleeve.
The spindle is a black tube made of hard tool steel. It is machined and has two shiny bearing surfaces. Note the slightly thinner area between the two polished surfaces. This bearing holds the platter on a vertical axis, keeping it from wobbling as it turns. A thick, galvanized, sheet steel part forms the support base for the spindle. It is 3-4 mm thick and the spindle appears to be a friction fit into a hole in the base. The spindle itself may also be flared slightly.The complete ball-bearing assembly has four parts, the photo showing three. On the bottom is a flat washer. On top of that goes the ball-bearing ring. Then a second flat washer rests on top of the bearings. Not shown is a black O-ring that rests on top of the second washer. Finally, the platter sleeve sits on top of the O-ring which forms a cushion between the sleeve and washer.
When originally assembled, grease was applied to the ball-bearing assembly, and to the sleeve bearing. Extra grease was left in the area of the spindle between the two bearing surfaces. Over time, the grease dried, locking the platter sleeve to the spindle.
Free PlatterFreeing the platter is simply a matter of applying some penetrating oil and waiting. The key is to have great patience. It can take several days for the oil to fully penetrate and loosen all the dried grease down to the bottom of the sleeve. First remove the album spindle and set it aside. It is not necessary to remove the rubber platter cover at this time. Apply the penetrating oil to the area shown, where the sleeve and spindle meet. Repeat the application several times a day as the oil disappears into the joint. Putting oil into the open tube of the spindle will do no good at all, since it cannot reach the bearing surfaces.
DO NOT attempt to rotate the platter to loosen it. This is how I damaged the spindle support. It is best to keep applying oil for at least 3 days without attempting to move the platter at all. If you must test it, gently lift the platter straight upwards, without any rotation. If the platter does not slide up easily, continue applying the penetrating oil. You will succeed if you continue to apply oil and wait patiently.
When the platter is free, you will need to remove it and clean all the bearings. To get the platter off, you need to remove a black plastic circlip on top of the spindle. If you have a pair of circlip pliers, great. Otherwise, use almost anything you like. Screwdrivers work. A pair of wooden sticks will also work and will not scratch the platter if you slip.
Lift the platter straight up and off. Remove the rubber pad and plastic sheet under that and set aside. Use some paint thinner to clean off the old grease and penetrating oil residue. Follow that with denatured alcohol to remove all the oily film. When the platter is clean, set it aside.
Cleaning and removing the ball-bearing assembly is a bit trickier. Looking down the spindle, you will be able to see the black O-ring and the top washer. You can also see part of a large, red, plastic gear. To get the washers off, you need to rotate that gear until a large notch is aligned with the spindle. This will give you enough room to wiggle the washers and ball-bearings past the gear.
If the ball-bearing assembly is still stuck together with dried grease, try applying more penetrating oil. Once it is loose, you can try using a long, thin stick to wiggle the parts along the spindle, past the gear and then off the spindle entirely. This will probably be easiest if you prop up the turntable on the front or rear edge. Be sure to lock the tone arm to the rest, and tighten down the shipping wing-nuts before tipping the turntable. As a last resort, you can remove the spindle base from the turntable platform. This gives you full and easy access to the spindle and bearings, but it is quite involved and requires constructing a work stand so you can flip the turntable upside down. See the articles on spindle repair.
Assuming you got the bearings off without disassembling the turntable, clean the bearing parts in paint thinner and denatured alcohol. Also swab the spindle and base with these solvents to clean them thoroughly.
When the parts are all clean, apply a small amount of lubrication to the bearing assembly and reassemble. I am not sure what the best lubricant would be, but I used a spray-on product called 711. WD-40 could also work, or even a drop of motor oil. When the ball-bearings, washers and O-ring are in place, swab a bit of lubricant around the bearing surfaces of the spindle. Do the same inside the sleeve on the platter. Then slide the platter back in place and replace the drive belt. This would be a good time to do a power up check to confirm that the platter spins and the automatic tone arm function is still OK. If all is good, reinstall the circlip, spindle and platter pad.
Damaged by Impatience
So what will happen if you succumb to impatience and rotate the platter? When I did this, I was initially thrilled because I thought I was making progress at freeing the grease. I did not know then how the platter and spindle were constructed. At first the rotation was difficult and it stuck more at some positions than at others. But as I applied more penetrating oil and turned it more, the platter became looser. It was only much later that I realized that the spindle was turning in the hole of the support base.
Eventually, I decided that what I was doing could not possibly be right. That was the point at which I embarked upon a path of disassembly and discovery. It would lead me to realize that I had destroyed the friction fit between the spindle and its support base. Instead of a steady support for the spindle on which the platter rotated freely, I had a platter still locked to a spindle that wobbled around in a distorted hole in the support base. Disaster.
Still, I was able to solve this new problem, but at a cost of several days of work. If you have suffered a similar fate, take hope. The next set of articles explains how to fix the damaged spindle mount.