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technics sl1200 mk2 oscillating speed

Z

zmoss48

New Member
So I got a used technics sl1200 mk2 turntable with a slight problem. I can see the strobe dots slightly moving back and forth around the correct speed, rather than staying completely still like they should. The turntable will stay maintain the correct rpm. I do not think that this is audibly noticeable, but it is still enough to make me paranoid. I understand that this is probably an old unit, but wanted to know if this is fixable.

-Zach
 
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Does this occur with the pitch control locked, unlocked, or both? Does playing with the pitch slider help any, or does it worsen?
 
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eiraved said:
Does this occur with the pitch control locked, unlocked, or both? Does playing with the pitch slider help any, or does it worsen?
Click to expand...

This turntable is quartz-locked. I only see this when the fader is at 0%, but I assume that there is speed variation at any speed. Playing with the pitch slider doesn't seem to help.
 
Does it behave the same when switched to 45? I had acquired an Akai turntable recently and the strobe indicated the speed pulsing a bit. I cleaned the pots and the speed switch. This cleared my issue. It was not a quartz controlled turntable though. It also has a coarse speed pot for 33 and another for 45. I cleaned these as well and followed the adjustment procedure in the service manual.
Yours is a very popular table and free copies of manuals are easily found. You will probably get some detailed help from someone more familiar with your unit.
 
El Rubio said:
Does it behave the same when switched to 45? I had acquired an Akai turntable recently and the strobe indicated the speed pulsing a bit. I cleaned the pots and the speed switch. This cleared my issue. It was not a quartz controlled turntable though. It also has a coarse speed pot for 33 and another for 45. I cleaned these as well and followed the adjustment procedure in the service manual.
Yours is a very popular table and free copies of manuals are easily found. You will probably get some detailed help from someone more familiar with your unit.
Click to expand...

It does the same on 45, and since the platter is spinning faster, the pulsating is also faster.
 
zmoss48 said:
What do you mean?
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The dots on the platter are the issue not the rotational speed, so they appear to be oscillating back and forth, the platter just isn't perfect. If the strobe light wasn't there you'd be happily spinning records instead of posting threads worrying about a non-issue.
 
Grenadeslio said:
The dots on the platter are the issue not the rotational speed, so they appear to be oscillating back and forth, the platter just isn't perfect. If the strobe light wasn't there you'd be happily spinning records instead of posting threads worrying about a non-issue.
Click to expand...

I'm not too sure about that. The movement isn't completely consistent, meaning that they move more on certain rotations of the platter.
 
There are so many things involved in spinning a disk you may never get it prefect. Variations in belt thickness, belt tension, durometer of belt material ie hard spots or softer spots. Is it direct drive? if so is the drive wheel perfectly round? Are the axles perfectly straight and perpendicular? Are any bearings with a slight amount of wear?
It is driven by a D.C. motor , what kind of motor brush less? Shaded pole? What does the D.C. voltage look like is it flat? Is it full wave rectified? You will need a scope to look at the voltage.
What condition are the bearings in? How circular is the path of the platter? Is the spindle perfectly straight? How round is the platter?
The list goes on and on. Nothing that is mass produced is perfect. Every thing can be made perfect but no one would be able to afford it. Every thing manufactured has acceptable variations according to the manufacturer set standards.
AS been stated if it sounds ok to you go with it or spend 20,000 dollars and get a perfect one.
 
How old is it? If it's upwards of 30 years in age, the electrolytic capacitors in the motor control circuit can be going bad, and that will cause instability in rotational speed.

So will a dirty or dry bearing for the platter, too.

Very nice turntable, well worth getting it rebuilt I think.
 
HPMguy said:
How old is it? If it's upwards of 30 years in age, the electrolytic capacitors in the motor control circuit can be going bad, and that will cause instability in rotational speed.

So will a dirty or dry bearing for the platter, too.

Very nice turntable, well worth getting it rebuilt I think.
Click to expand...
Any chance of the pitch control requiring a cleaning? Never owned one.
 
Grenadeslio said:
The dots on the platter are the issue not the rotational speed, so they appear to be oscillating back and forth, the platter just isn't perfect. If the strobe light wasn't there you'd be happily spinning records instead of posting threads worrying about a non-issue.
Click to expand...

actually you might be right. I noticed that the oscillating is synchronized with a slight up-and-down movement of the platter edge.
 
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