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Yamaha PX-3 Tone Arm Issue

What a callous and nasty response I thought in bed last night!!
Don't go back into the tonearm base trying to correct this.
Go through the checking/adjustment procedure, checking VR1 and VR4 at the test pin (note these instructions are similar but different for PX2) and adjust them per the repair manual (0V +/- 50mV)
If you then find that the arm doesn't come to 90*, go ahead and adjust VR4 until it does. I have done this in practice on PX2s and I also see a tech made a similar note in my copy of the repair manual that he set it to 300mV to trim it. (If you look on the circuit diagram, VR4 adjusts the bias of CDS sensor)
I recollect setting the cartridge down on something I put near the platter's edge, and being able to watch the correction angle of the arm change as I adjusted VR4, but remember, I was recently released from the NJ Home for the Mentally Enfeebled!

PS: it just occurred to me, perhaps check the two values and set them. See if it's OK>>DONE
If not, then while monitoring in tonearm down/tracking @90* position mV and adjust at the CDS for 0V +/-50mV, and see if everything gets right.

OR>the easy button.
 
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How about now? Are you telling me that yours is perfectly at 90? Because that would cause the arm to creep. I don't think it is supposed to track at perfect 90 degrees due to some wobbly out of center records that is why the arm has a dead zone in center.

Yes I'm familiar with all the calibration pots and their settings. Its all set per svc manual except the VR4 which I have tightened by eye to get a more symmetrical tangency.
Cant go too crazy as that would cause arm to creep etc.

If the arm has too much play when we pause the music by raising the arm it will straighten itself by moving right and skipping allot of music when dropped down again. So best setting is as close to 90 that when it lifts is just rewinds 3 seconds of music or so and no more.
Makes sense?

I WOULD STILL LIKE SOME PICS FROM OTHER PX-3 OWNERS...

And previously, not sure what you meant by "Rotated in" did you mean tilted in?
.974CBF60-6CD4-44C7-BBFD-FBF0AF5741BA.jpeg3CBD9FB3-644C-41C3-9251-65664F7DCE43.jpeg
 
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RCHeliz said:
And previously, not sure what you meant by "Rotated in" did you mean tilted in?
Click to expand...

Yes.
The manual states "maximum horizontal tracking error: +/-.15*
That would make for a pretty small window of arm=wandering!
I've never experienced this "creeping" when I set one up.
I checked my go-to PX2 and it seems to drop back into the same phrase it lifted from, probably accurate nearly or to a single groove.

PS: I have never adjusted the window in the CDS-1 and there is no information about it in either 2 or 3 repair manuals. (for that matter, there also is no info about the "arm up" switch adjustment in the rear of the arm by the damper)

PPS: "creeping"? The tonearm positioning may oscillate if the rear cover is off and (reasonably strong) light strikes the rear of the deck.
 
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Well if you leave arm at 90 and turn VR4 too much, you will see that it starts to creep which is normal but once creeping turn back a bit and all good. I adjust in low light of course.
 
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Leave the arm with the cartridge resting on something as high as the platter, just off from the platter, and the arm free/deployed, tracking (responding to arm deflections as when playing).
You should be able to dial in 90 degrees with V4.
 
Precisely how I calibrated it. On a piece of styrofoam. :) I'm happy with the angle now. Sounds fantastic listening to a great copy of ThompsonTwins
 

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I’ve used Sam as well as some of the techs he’s trained. Indeed he’s one of the good ones. My experience with the professor has all been good so I can’t comment further.
 
I plan next to build a circuit that will shut off the opto-couplers when they are not in use. Eg after arm returns to park. This way we can leave the TT powered ON all day.
 
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RCHeliz said:
I plan next to build a circuit that will shut off the opto-couplers when they are not in use. Eg after arm returns to park. This way we can leave the TT powered ON all day.
Click to expand...

That's a great idea. But, remembering the Prof's sage advice, (shortening your springs will devalue your collectible turntable!) doing so, no matter how practical, will detract from the deck's desirability:)
Me, I leave mine on continuously, but all my components are on a dedicated 20A circuit with a switch on the side of the table it's on. (it's the dark blotch that would be to the left of my left leg)
 
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Wow, nice and cozy place you have there...

Re:springs
I did not short them because the belt is in top condition and very tight as is. I'd rather hunt for a pair of tighter spring insead of messing with the originals, but in my case I don't need to change or mess with them yet and probably never will. If the transport is well maintained, table leveled and arm operation is smooth they should be fine. I did bathed them in light turbine oil to preserve their composition against rust etc. Wiped them down so they will not drip any oil or pick up dust, shall last for a long time.

As of the photo-interupters, no matter if you have a UPS or protected strip, which does help against power spikes etc, they are still constantly powered on which from what I understand will wear down and either the LED's or the receivers can get weak with time, which is what the problem people seem, to have with them. Mine are still nice and bright.

The idea is to keep them off when TT is powered on but does not have any activity or arm is not in operation.
My turntable is plugged into the Yamaha pre-amp rear outlets so it comes on when the pre-amp is powered on and all plugged into a UPS.

B1FD1024-25B4-463D-BB57-D94F4A261A66.jpeg
 
The LEDs in the interrupters get weak (or fail) which is why you can McGuyver it, replacing just the LED in situ.
My deck is plugged into my Yamaha pre-amp which is always switched on as well as my tuner and power amp. Everything comes up when the 20A switch is flipped. I leave the tuner selected so it's like turning a radio on. This main system doesn't get run that much and half the time it's for vinyl so there's little concern for interrupter degradation-and if it did, I actually have a NOS set as well as the belts. I'm in it for the long run, with some apologies! (a favorite response of mine when someone had a loss, like a burnt up trans was 'in 20 or 30 years, what the hell difference will it make'......until someone reminded me, in 20 or 30 years I'm likely to be dead! I'm 73:)
 
RCHeliz said:
And here it is, smooth and nimble with perfect 90 degrees action. Both L/R read even at full deflection -3.6v and +3.6v yeyii!
Click to expand...


https://www.audiokarma.org/forums/i...7ad-2520-4c3e-af6a-c9a684ad6145-jpeg.1785641/

Hey, RC, if you're paying attention, what is the lever with the perpendicular (in photo link above) spring doing and what is the shiny/chrome box on the left of it?
And, it looks like the gray plastic eccentrically mounted "stop?" across the lever from the chrome box is a factory preset adjustment? of it?
I've never had occasion to open up that part of the decks and am real curious!
 
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clinic-audio said:
Hello RCHeliz

I know perfectly PX3, PX2 and PX1
I am working right now on a PX1 who will be ready next month (long , long , work)
Regarding your trouble : it is the same on all YAMAHA PX3 and PX2
The problem is coming from here :

View attachment 1775209

the problem is that the flat belts slip on the pulley and the motor can't compense enough to keep the tone arm strait

The only way to repair it is to replace the drum by one upgraded one like this

View attachment 1775214

this new drum will never slip and your tone arm will go back to normal function


View attachment 1775217
Click to expand...
Where can I find one of these it's the problem
Thank you
Scott ❤️
 
Hello everybody, a few years back I got one of these Yamaha PX-3 TT, and I think now it's a perfect time to restore it and swap my Bang & Olufsen TT.
Power it on; all the lights are on. I tested the tonearm, and it's "broken." Sliding left and right is almost not happening.
I took it all apart, removed the tonearm assembly, investigated the issue, did some reading, watched YT, and started taking it all apart. 3 belts are swapped, the cleaned rubber wheel is with alcohol, and later with SONAX. Cleaned all plastic pulleys with alcohol, and reverse wide rubber belt ...aaaaand the tonearm still not moving :bye:
I applied about 1.5V on the motor, and all powered belts and pulleys started turning, except the wide belt, it is slippery on the plastic pulleys, while power was applied to the motor I pressed the belt from the top, and the tonearm started moving, so basically I think two springs that hold this belt together are weak. Is there a replacement that I can buy, or I need to make this short?

PS All caps are in order from Mouser. Special Thanks to @dlucy !

Any help will be greatly appreciated.
 

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