Yamaha PX-3 PX3 Tonearm Tracks at an Angle

[the_chemist]

Hello all,

I'm hoping to find a PX-3 expert here who can help me.

I bought a Yamaha PX-3 on ebay, (first bad move), from a person who claimed it worked 100%. We all know each and every ebay seller is completely honest!

I paid through the nose for the unit because it came in the original box with original packaging and all the accessories, including transit screws and tonearm shipping clamp.

When I first tried the PX-3, the tonearm would not move out of its rest position unless you helped it along.

Playing an album, the tonearm tracked crooked, facing quite a bit towards the center spindle. Tonearm ahead of the carriage.

I took the unit apart cleaned the large flat belt with mineral spirits, then flipped it over to use the opposite side.

I also removed and replaced all 3 pulley belts that drove the large flat belt. I cleaned all three pulleys and motor spindle as well with IPA, as they felt oily to me.

I achieved success in getting very grippy traction for the tonearm drive system after the "operation". It can literally move the tonearm at quite an inclined angle now.

I also replaced the Audio Technica "P" mount cartridge that the seller had installed.

I really had to laugh here. The guy must have been a real idiot. He had the cartridge moved the entire way to the front of the headshell.

If there were such a thing as overhang on a linear tracker, it would have been at least half an inch past the center spindle.

I tried pushing the "P" mount adapter as far back as it would go, but the adapter hit the rear down-curve of the headshell making it impossible to line up the stylus with the center of the record spindle.

Needles to say I changed out the cartridge with a NOS Shure M91ed 1/2" mount cartridge, just for testing purposes, before I install something good.

I thought sure (no pun) that the excessive onethang would have been the cause of the tonearm tracking tangency issue, but it was not...

I then got the service manual and adjusted the tracking angle using the test pin under the platter along with VR1 & VR4.

The service manual states to adjust VR1 in the tonearm up position to 50 mv +, - 10 and adjust VR4 in the tonearm 7 mm down position to 50 mv +, - 10. I achieved 53 mv in both positions.

I performed these adjustments with the tonearm midway between its rest position and where the platter edge would be if it were on the DD spindle shaft.

Well, no luck, the tonearm still tracks crooked way ahead of the carriage.

I found that turning VR4 to its full clockwise position (didn't even bother to measure its voltage at this point), almost provides perfect tangency. BUT, with the tonearm down between the rest position and platter, it will move towards the platter. The tonearm drive motor is always on when the tonearm is down. The tonearm will track towards the rest position if moved by hand in that direction though...

Something else must be out of spec somewhere for this condition to exist, but I don't know where to look.

Possibly, there is a tangency sensor that is not working or aligned improperly. I don't know enough about these to even begin to know what to try next.

The turntable is on a level surface of course...

Possibly, the electronics have drifted out of tolerance for me to have to turn VR4 fully clockwise in order to achieve almost perfect tangency

Does anyone that has experience with these PX linears know anything to have me try in order to correct this?

I would be very grateful for any pointers or ideas of things to try. Especially if we can cure the problem.

One other thing, it takes an eternity for the tonearm to rise up when cued. It's almost like the viscous damping cylinder is all gummed up... Drops nicely though.
Any ideas there?

Thanks in advance for anyone willing to help me!

 

[Dr. Ear]

A possible cure: There is a contact that tells the microprocessor if the tonearm is either up or down. This is crucial. If this contact is not adjusted properly you will encounter malfunctions like you described. There are two different versions of the tonearm, in my PX-2 it is a Reed contact whereas in my PX-3 it is a adjustable mechanical contact. At the right rear end of the TA assembly there is a small hole where you can adjust the angle of the tonearm when the contact shuts resp. opens.
Don't mind the slow lifting of the arm, this is almost normal.

 

[the_chemist]

Thanks so much for a reply, I took a picture of what I think you are referring to. Is this it? I think that is working alright...

A possible cure: There is a contact that tells the microprocessor if the tonearm is either up or down. This is crucial. If this contact is not adjusted properly you will encounter malfunctions like you described. There are two different versions of the tonearm, in my PX-2 it is a Reed contact whereas in my PX-3 it is a adjustable mechanical contact. At the right rear end of the TA assembly there is a small hole where you can adjust the angle of the tonearm when the contact shuts resp. opens.
Don't mind the slow lifting of the arm, this is almost normal.

 

[the_chemist]

A possible cure: There is a contact that tells the microprocessor if the tonearm is either up or down. This is crucial. If this contact is not adjusted properly you will encounter malfunctions like you described. There are two different versions of the tonearm, in my PX-2 it is a Reed contact whereas in my PX-3 it is a adjustable mechanical contact. At the right rear end of the TA assembly there is a small hole where you can adjust the angle of the tonearm when the contact shuts resp. opens.
Don't mind the slow lifting of the arm, this is almost normal.

Here are photos of the arm up and down with the adjustment.

I also misquoted the service manual in my original post. I stated that the up and down voltages of VR1 and VR4 were 50 mV +, - 10 mV. That was totally incorrect. It should have been 0 mV +, - 50 mV.

I have it set to 0.001 volt up and down. The arm still tracks ahead of the carriage (photo attached) unless VR4 is turned fully clockwise (tonearm drive motor always on in the down position).

Something is misadjusted somewhere...

I just don't know what to adjust.

[

 

[gary7]

Here are photos of the arm up and down with the adjustment.

I also misquoted the service manual in my original post. I stated that the up and down voltages of VR1 and VR4 were 50 mV +, - 10 mV. That was totally incorrect. It should have been 0 mV +, - 50 mV.

I have it set to 0.001 volt up and down. The arm still tracks ahead of the carriage (photo attached) unless VR4 is turned fully clockwise (tonearm drive motor always on in the down position).

Something is misadjusted somewhere...

I just don't know what to adjust.

View attachment 2455960 View attachment 2455961 View attachment 2455962[

Just looking at some PX-3 threads. Did you ever get yours working properly? I've had four of these since 2016. Just got another about month and half ago.