Technics SL-QD33 tonearm play

[Ldsc2002]

Hi,

I recently noticed the tonearm on my Technics SL-QD33 turntable has some play on the vertical pivot. The horizontal pivot has no play at all, but the play on the vertical pivot is enough that I can twist the whole tonearm a couple degrees to either side.

Is this something I should worry about? Can I damage my turntable by using it like this?

Any advice is appreciated!

 

[Nat]

I'm assuming that when you say vertical pivot, you mean the pair that allow for vertical motion, rather than the ones oriented vertically - I used to think that identifying them by their orientation was right, but I was wrong. If you can rock them a couple of degrees, that seems pretty loose, and if you are handy at fine work, you can probably tighten them a bit, if you want. But you could also leave it alone - you won't damage anything, though you might be missing out on some detail in the sound produced
If you do want to tackle it, you need a flat head screw driver that fits properly in the screw (pivot pin) in the center of the bearing, and a spanner that fits the two slots in the locking ring. There are all sorts of kludges for the spanner, but most will mar the surface (as will even a correct spanner if used carelessly). An appropriate size flat head screwdriver with the center filed out so that you have two tines that fit the slots of the locking ring is excellent.
You only need to do one of the bearings. Back off the locking ring just enough to allow the screw (pin) to move (if you go too far, the pin may not stay in the bearing and then you'll have to locate the proper place for it, which is an added and unneccessary pain). Gently screw the pin in until it makes contact - gently, not hard, since you don't want to mash (brinel) the bearings. Back off an eigth of a turn to allow enough slop so that friction is minimized (there are bearing that work tight, but they cost the earth and aren't found (or needed) in commecial turntables). Holding the pin in place, and the spanner or cut out screwdriver (at an angle to clear the small screwdriver) turn the locking nut to mostly tighten it. Then tighten more fully, offering resistance to the pin turning, if you can. Finally, give a bit of torque with the spanner or cut out screwdriver to fully tighten it. The pin should not move much at all.
You can check your work by removing the stylus, balancing the arm, and seeing if it oscillates freely. Paul (Delihaus) used to suggest eight oscillations as perfectly fine, but this was with the arm held up and down - in normal position, the range of motion is so limited that you may get less. But it should oscillate several times - as a test, see how your arm does right now, so you have a standard of comparison that is fair.

 

[Ldsc2002]

Thanks for the detailed guide! I am actually incorrectly referring to the pivot that is oriented vertically. I suppose I can follow the same procedure to tighten the other pivot, but I cannot find where to adjust it.

I think I want to adjust it if it’s not too difficult. My records sound fine to me, but it kinda bothers me that a completely new turntable was like that from the box. If it seems too difficult, or I think the chance of breaking something is high, I will just leave it as is knowing that it won’t get damaged by using it like that.

 

[Nat]

In that case, you may not have a problem at all. You can almost always induce some rocking in horizontal bearings that use ball races. This is because it is really only the top race that does the work and the weight of the whole arm, not the bottom race, is what keeps it tight in use. The bottom race merely keeps the bearing together during handling so that the ball bearings don't fall out (which they most certainly will if you take the bearing apart). Tightening the bearing will simply increase friction, not improve sound. Recognize that in use, the arm is not subject to force like you are exerting on it when you vigorously torque it. A more accurate test is to use the tiniest amount of force possible to twist and push and pull and see if the arm moves without your having actually lifted it off the bearing.

 

[warrjon]

Those Technics arms don't use cage bearings. The bearings are ball race with no central cage. There is a pin ground at 60deg that engages the center of the balls. There should be no movement in the bearing assembly.

P2 of this document has bearings similar to what Technics uses.

 

[Ldsc2002]

The bearings are ball race with no central cage. There is a pin ground at 60deg that engages the center of the balls.

I have seen a similar type of bearing used in mountain bikes, some manufacturers use them and they can be a pain to adjust properly.

Do you know how to adjust it? I have seen other Technics tonearms have an adjustment on top, but this one has a cap that doesn’t look like it can be removed.

 

[Nat]

Hmm - a different model than I was thinking of - hadn't realized it was a Pmount. I looked at the service manual over at Vinyl Engine, and the whole arm is a unit so no details about the bearing, but it clearly is a pin bearing, not a ball race at the top, and, one would assume, at the bottom. So it could be tightened. Is there a cap on the top bearing that pops off?

 

[Ldsc2002]

So it could be tightened. Is there a cap on the top bearing that pops off?

I checked the tonearm and I am 99% sure the top cap is not removable. When I try spinning it, it doesn’t move, and there is not enough space between it and the rest of the tonearm to try lifting it without destroying the finish.