Yamaha PX-3 Linear Tracker doesn’t advance

[Musicman524]

Boy is this thing driving me crazy! lol

I’ve taken this thing apart way more times than I want to admit. I get it all back together and all functions are perfect. Once the needle goes down once, it won’t move left anymore.

It seems like something I’m doing while taking it apart (maybe flipping it upside down) fixes the issue until the arm tries to track a record and then the left side dies again.

Is there some kind of mechanism inside the tonearm assembly that controls the motor? If I put a tiny amount of pressure towards the right of the tonearm the motor kicks on and the whole assembly goes right. Pushing the tonearm towards the center of the platter does nothing.

I can move the controls around all over the place for however long and then as soon as the needle tries tracking the record, the motor control is gone.

Any ideas?

Thanks,

Matt

 

[Fishead]

Have you checked the three small belts that drive the motor? Just a thought off the top of my head and an easy fix if you're lucky.

 

[Musicman524]

Belts all look good and motor works in both directions until the arm lowers and it tries tracking a record. After that the arm goes up and right, but not left. The inside of the tonearm assembly does look pretty gummed up, but doesn’t look like fun to get at.

 

[Fishead]

So, what you're saying is that:
(1) the arm cues when you press the 33 or 45 buttons, meaning it lifts from the resting position far right and moves to the beginning of the record and drops. Is this correct?
(2) once the arm drops on the record, it will not move towards the left (towards spindle) and essentially acts like the record has a bad groove that keeps it stuck at that spot, correct?
(3) operation with the << and >> buttons will cause the arm to lift and then move in whichever direction that you are pressing, correct?
(4) if you nudge the arm while it is in the up position to the right, the arm moves and returns to rest position, correct?
(5) if you nudge the arm while it is in the up position to the left, nothing happens, correct?

If all of those points are correct, then it sounds to me like the arm is not responding to the "call" for movement to the left. This is another of those "top of my head" guesses but from the work I did earlier this year on my PX-3, when you look at the rear of the arm there is a switch which must make contact or remain open depending on the mode that the turntable is in. See here:



I would try running the table and watching the movement of that switch to make sure it is opening and closing as it should. This may or may not be relevant, but it was in my case.

Next, make sure all of the photo interrupters are producing a strong, red light.....and let's hope they are because if one of those are out, well, let's just say they are not available and fixing them requires much more expertise than I have. This will require, more than likely unless you have very advanced skills at such things, sending them to someone who does this for a living and has repaired many. He was once a member of this site but has since moved on, now occupying a residence on the big auction site and seems pretty busy and not likely to get to your repair any time soon.

Let's not get ahead of ourselves though, could be something a whole lot more simple such as a dirty mechanism keeping things from moving properly.

Again, with the arm in the up position and having moved it to the beginning of the record with your << button, if you then nudge it to the left with your finger, there is no corresponding response, as in slight movement of the arm in that direction? But, if you do the same thing and nudge it to the right then it does move slightly to the right......hmmmm......this is telling me that the arm is not actuating the sensor in the arm base that tells it to move.

Stay with it amigo, there is an answer.....it's just not plainly available yet......

 

[Musicman524]

So, what you're saying is that:
(1) the arm cues when you press the 33 or 45 buttons, meaning it lifts from the resting position far right and moves to the beginning of the record and drops. Is this correct?
(2) once the arm drops on the record, it will not move towards the left (towards spindle) and essentially acts like the record has a bad groove that keeps it stuck at that spot, correct?
(3) operation with the << and >> buttons will cause the arm to lift and then move in whichever direction that you are pressing, correct?
(4) if you nudge the arm while it is in the up position to the right, the arm moves and returns to rest position, correct?
(5) if you nudge the arm while it is in the up position to the left, nothing happens, correct?

If all of those points are correct, then it sounds to me like the arm is not responding to the "call" for movement to the left. This is another of those "top of my head" guesses but from the work I did earlier this year on my PX-3, when you look at the rear of the arm there is a switch which must make contact or remain open depending on the mode that the turntable is in. See here:

View attachment 3834059View attachment 3834060View attachment 3834062

I would try running the table and watching the movement of that switch to make sure it is opening and closing as it should. This may or may not be relevant, but it was in my case.

Next, make sure all of the photo interrupters are producing a strong, red light.....and let's hope they are because if one of those are out, well, let's just say they are not available and fixing them requires much more expertise than I have. This will require, more than likely unless you have very advanced skills at such things, sending them to someone who does this for a living and has repaired many. He was once a member of this site but has since moved on, now occupying a residence on the big auction site and seems pretty busy and not likely to get to your repair any time soon.

Let's not get ahead of ourselves though, could be something a whole lot more simple such as a dirty mechanism keeping things from moving properly.

Again, with the arm in the up position and having moved it to the beginning of the record with your << button, if you then nudge it to the left with your finger, there is no corresponding response, as in slight movement of the arm in that direction? But, if you do the same thing and nudge it to the right then it does move slightly to the right......hmmmm......this is telling me that the arm is not actuating the sensor in the arm base that tells it to move.

Stay with it amigo, there is an answer.....it's just not plainly available yet......

All correct except the tonearm doesn’t advance left with the fast forward button. It will work intermittently, but once the tonearm drops and raises it seems to stop. When I nudge it right; it returns. When I nudge it left, nothing.

 

[Fishead]

OK, so the tonearm does not move if you push the << button, but (1) it does move if you push the 30 or 17 buttons, correct? (2) It advances to the left to the edge of the record and drops, correct? And (3) does it pick up off of the record if you push the << button? If all that is correct, then it is beginning to sound like there might be a component that has given up the ghost, a cap or resistor or something along that order. I wonder if @dankik might chime in here. He understands schematics and can make sense out of them.....

 

[Musicman524]

All of the buttons work before the first needle drop. (When it’s working) then after then arm tries to track a record I lose all left motion on both the auto and manual. Although, now I can’t even get it to intermittently work ‍

 

[Fishead]

Have you checked to see if the photo interrupters are working? That is, do all three have a strong, red beam? The beam will only be coming from one side, the emitter side, as the other side is a receptor. Even if the emitters are indeed producing a good beam, the problem can just as likely be receptors that are not working. Were you able to see if the switch in back of the tone arm is opening and closing as it should? Those are the two most likely suspects but again, it may well be that you have some issues with your other components and for that you will need the schematic and a way to test them. I wound up doing a complete re-cap along with replacing other components before things started working properly again. If you haven't already, you might consider having a look at the thread I started for pointers on what the process looked like for me. Here's a link that will take you deep into the thread where I mention some things that were key:

Post in thread 'Yamaha PX-3 photointerrupters and other issues causing problems'

Apr 15, 2025

Update: Well, 13 days later (tax day on top of the unlucky number as well......) and the PX-3 is still working perfectly!!! I'm knocking on every piece of wood in my immediate proximity!!! Aside from reporting this good news, I also wanted to update this thread in the interest of providing others further information that I have since gleaned through a contact with the good Professor Bizzt, who has been very kind to reply to several emails back and forth on the nature of the PX-3 dilemma. First, it would seem that the photo interrupters for some reason are much more likely to fail in...

• Fishead

• 

You can then go back and have a look at the whole thread if you like which kind of details, blow by blow, where the process took me. The good news is that the table has been working flawlessly since, but it sure took some doing to get it there......good luck amigo

 

[borchee]

Were you able to see if the switch in back of the tone arm is opening and closing as it should?

The switch should be checked for:
- phisycal contact
- conductivity.

Clean the contacts anyway - just pulling writing paper through/between closed contacts might be enough....observe the residue on the paper. Ideally, you would squeeze the contacts between fingers whilst pulling paper through. If you have some king of a contact cleaner, use it.

Make sure that rails, guides, pulleys, belts, optical elements and what not are clean.

If you don't have the service manual, a good copy can be obtained at manualslib.

 

[dankik]

@Musicman524, what test equipment do you have and can you read a schematic diagram. Are you familiar with troubleshooting electronics?

 

[Musicman524]

@Musicman524, what test equipment do you have and can you read a schematic diagram. Are you familiar with troubleshooting electronics?

I have oscope, signal generator, dmm, transistor tester etc. I can read a schematic and have fixed a lot of things in the past. This one is giving me a run for my money because it works for a moment and then back to no motor control.

 

[dankik]

Thanks. I think we should start by measuring the voltages on IC2.
Here are the pin functions (from helping @Fishead with his PX3).
Measure both before you push any buttons, then after you press the DOWN button.