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Yamaha PX-3 Tone-arm repair and parts needed

G

GlennD

New Member
I am in need of a replacement "ARM CONTROLLER" Tact button. It is a snap-in 12mm x 12mm square button and is made by ALPS. It has 2 internal switches activated by more or less pressure on the button.

Another problem to sort is that sometimes while lowering the tone-arm, it will travel towards the left or centre by as much as 60mm! Has anyone seen such a problem and know of the cure? Why is it moving?

Thanks much!
 
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Wrote up a long winded, deep explanation, but there are a few things you can check for the "race to the left" problem.

First, see if the arm descends too slowly. The damping grease can be too dry, dirty, or worn out and can be replaced with 100k silicon damping fluid used for RC cars. How fast is fast enough for the descent is hard to measure but I think there's a timer chart in the service manual that shows how long the IC chip waits for the needle to make contact.

If the arm isn't straight in the gimbal, that's another problem with a range of solutions. Check to see if the arm is "stiff" when the table is off and in the neutral home position. You shouldn't be able to wiggle the arm left and right, it should feel almost locked. Take a look at the angle of the gimbal blocks also, they should form 90 degree angles in relation to the arm at rest. If it looks crooked (uneven gaps in the blocks), you may have a mechanical problem.
 
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GlennD said:
Another problem to sort is that sometimes while lowering the tone-arm, it will travel towards the left or centre by as much as 60mm! Has anyone seen such a problem and know of the cure? Why is it moving?
Thanks much!
Click to expand...

Is the whole tonearm assy moving, or just the tonearm?
 
I bet it's the whole assembly. Then again this guy probably just registered and posted four things, got no replies and bailed. We'll see. :)
 
Its very easy to fix the tonearm assembly moving to the left or to the right while cueing. There is a cover under the platter, you remove it and there is a test point and a trim pot, put one probe of a multi meter there and another to a ground point.. First you set that trim pot to as close to zero as possible while the arm is in the up position (within 50 mv). Next you lower the arm but play with the counterweight so that it floats close to the height of the platter and you have to adjust a blue trim pot that is located on the arm carriage, you can get to it from behind the table. You also set that trim pot to as close to zero as possible, using the same test point as before, and the arm will no longer wander.
 
IME that adjustment trims the tangency of the arm slightly, not 2+inches..
Also, I've found more than once that I needed to set the second adjustment to a slightly different value than spec to restore tangency/"square" the arm when tracking a groove.
If the original poster could clarify what's actually happening, it would be helpful.
 
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