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PX-2 Tonearm Drives? What's really original

pfcs49

pfcs49

Phil
Subscriber
When I got my first PX-2 turntable, I was surprised to find the late PX-3 type tonearm drive (3 tiered/all belts) in it. Then I saw somewhere that the PX-3 arm assembly superseded the worm-drive PX-2 arm in Yamaha service literature. (i.e: if a PX-2 needed a tonearm replaced, Yamaha only supplied the later/PX-3 all belt-driven arm assy)

When I got my second PX-2 recently, I found it also had the later all belt-drive setup. But, I purchased it from the original owner who bought it new from a dealer in 1982 and swears it was never out of his sight till he sold it to me. (i.e: the tonearm is original)
I've seen 3 other PX-2s and one of them also had the PX-3 style tonearm azssy. That's 3 out of 5 having the later arm. Did late production PX-2s came with the later (all belts) tonearm?
If you've seen inside your PX-2, what drive system did it have and what is the serial number?
Mine are #05,483 and 06,003.
See picture of worm-drive unit here:http://www.thevintageknob.org/YAMAHA/PX2/PX2.html
 
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Look in from behind

Rich-
If you look at it from behind (it helps if you remove the dust cover), draw your attention to where the wide flat belt disappears under the turntable body on your right. If you have the all-belt/late style, there will be a whitish ~1" pulley visible on the front edge and below the wide (~1 1/4") flat belt and parallel to it. It will have 2 narrow ~2mm wide belts on it.
If you have the earlier/worm drive, you'll be looking at the back of the plastic motor housing.
Regards, Phil
 
Would not be surprised to see late production PX-2 turntables with the PX-3 drive system factory installed. Yamaha sometimes installed service station upgrades on late production units at the factory!
 
One of the reasons why they may have started using the later mechanism is this. On the PX-2 arm I think they found stray light was interfering with the optical size and runout sensors. There are a couple of pieces of black plastic glued to the PX-2 arm whereas on the PX-3 arm the metal was extended to cover the same area as the plastic.
 
Yamaha PX-2 & PX-3 tonearm drive schemes

pfcs49 said:
When I got my first PX-2 turntable, I was surprised to find the late PX-3 type tonearm drive (3 tiered/all belts) in it. Then I saw somewhere that the PX-3 arm assembly superseded the worm-drive PX-2 arm in Yamaha service literature. (i.e: if a PX-2 needed a tonearm replaced, Yamaha only supplied the later/PX-3 all belt-driven arm assy)

When I got my second PX-2 recently, I found it also had the later all belt-drive setup. But, I purchased it from the original owner who bought it new from a dealer in 1982 and swears it was never out of his sight till he sold it to me. (i.e: the tonearm is original)
I've seen 3 other PX-2s and one of them also had the PX-3 style tonearm azssy. That's 3 out of 5 having the later arm. Did late production PX-2s came with the later (all belts) tonearm?
If you've seen inside your PX-2, what drive system did it have and what is the serial number?
Mine are #05,483 and 06,003.
Click to expand...


Hello pfcs49,

I am as sure as I can possibly be that the PX-2 never used a worm-drive to move the carriage. It uses a wide flat belt that is in turn driven by a reduction gear assembly ("bearing base assembly" in official Yamaha language). This reduction gear assembly is in turn driven by a belt that is driven by a small motor.

The only 1/2" mount SLT turntables (that I am aware of) that used a worm gear drive were the Aiwa turntables.

The PX-2 and PX-3 turntables had tonearms that were VERY similar. The gear reduction assemblies were a little different, but were certainly more similar than dissimilar.


Best wishes, Professor Bizzt
 
No-not like B&O worm drives-

Both PX2 and PX3 use the same wide belt to propel the tonearm carriage (lets call it the final drive). All PX3s have 2 steps of gear reduction" via small pulleys driving large pulleys with small belts, the ratio being about 5/1 in each step, and the second pair of pulleys using dual belts (to transmit the larger torque) to the large drive drum of the final drive/wide belt.
Some PX2s use a single small belt from the motor to a large pulley that then drives the final drive roller thru a worm gear. This results in the axis of the motor being rotated 90*. The PX3 setup has all the shafts and armature parallel, with the 2nd large (dbl groove) pulley visible (without disassembly) adjacent to the final drive drum.
PX2s that have the worm drive setup show the back end of the motor housing there; at the other end of the motor is the small pulley that drives a larger pulley on the worm gear shaft.
PX2 literature describes the worm gear setup, but experience seems to show that the all-belts PX3 type is more common. I would like to determine by observation and serial numbers, if there was a point where there was a change to the later/PX3 style tonearm drive.
 
pfcs49 said:
Both PX2 and PX3 use the same wide belt to propel the tonearm carriage (lets call it the final drive). All PX3s have 2 steps of gear reduction" via small pulleys driving large pulleys with small belts, the ratio being about 5/1 in each step, and the second pair of pulleys using dual belts (to transmit the larger torque) to the large drive drum of the final drive/wide belt.
Some PX2s use a single small belt from the motor to a large pulley that then drives the final drive roller thru a worm gear. This results in the axis of the motor being rotated 90*. The PX3 setup has all the shafts and armature parallel, with the 2nd large (dbl groove) pulley visible (without disassembly) adjacent to the final drive drum.
PX2s that have the worm drive setup show the back end of the motor housing there; at the other end of the motor is the small pulley that drives a larger pulley on the worm gear shaft.
PX2 literature describes the worm gear setup, but experience seems to show that the all-belts PX3 type is more common. I would like to determine by observation and serial numbers, if there was a point where there was a change to the later/PX3 style tonearm drive.
Click to expand...

Hello pfcs49,

I took a lot of pictures of a PX-2 I recently worked on, but I have yet to post them in the "Gallery" section of the Vinyl Engine (that is where I post all my close-up pictures of turntable internals).

I know I have close-ups of the PX-2 reduction gear mechanism you are referring to and yes it did use a small worm gear for part of its gear reduction. I apologize as I thought you meant a large worm gear main drive as on an Aiwa LP-3000.

The brochure I have for the PX-3 clearly indicates there is difference between the reduction gear geometry of the PX-2 and PX-3. This PX-2's tonearm drive motor axle on the one I repaired was arranged parallel to the direction of lateral carriage movement.

The PX-3 brochure I have shows the drive motor's axle arranged perpendicular to the direction of carriage movement. I was not aware that some of the PX-2s used the same or similar reduction gear as the PX-3.

But I'm wondering... Why is this important to you?


Best wishes, Professor Bizzt
 
This is pretty interesting-

Here's a post from Vinyl Engine:

"
j_sunne
junior member


Joined: 17 Jan 2009
Posts: 3
Location: Connecticut
Posted: 04 Feb 2011 05:52 Post subject:
Now I get it. I have the design similar to the PX3. Not the one shown on TVK upon a closer look. There's three smaller belts and 2 pulleys driving the spindle that moves the main carriage belt. Interesting. Mine was manufactured in Nov 79 but it could have had the assembly replaced by it's previous owner. Were the PX2 and PX3 released concurrently? Perhaps it was addressing a design flaw?"
"Mine's an early production unit: Ser# 1179, with a test sticker of Nov 79. ":scratch2:

Here is a picture of the early/"worm-drive" on The Vintage Knob:http://www.thevintageknob.org/YAMAHA/PX2/PX2.html
 
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That's me.

I wonder if anyone has the worm gear. It's seeming pretty infrequent. I'll ask the original owner if he ever got the table serviced. He bought this in 1980, as noted above it's manufacture date was Nov79.
I can't imagine the change was anything more than an improvement over some cost cutting. This is Yamaha's TOTL one could have gotten their hands on in the US.

I give it a month until a PX2 listing on that auction site has a listing noting a PX2 with the rare and highly desirable worm gear tonearm!

a bit off topic: since many px2ers are in this thread, does anyone have a copy of the service manual? The usually recommended source hasn't gotten back to me.
 
i own two px2's and two px3's. all of them except for one px2 has the later version tonearm.
i can't see why the earlier tone arm is more desirable?
 
PX-2 Tonearm Drives? What's really original?

I could be wrong, but I see a what may be premature conclusions developing and solidifying here.

The last thing we need in this hobby is more audiophile opinions solidified into "fact" after snowballing from misplaced conjecture and abbreviated analysis.

So I say WHOA, let's slow down here and analyze this with a rational and professional discipline.

Who has the data to show that the two different PX-2 mechanisms have dissimilar reliability track records?

Who has the data to show that the two different PX-2 mechanisms have dissimilar performance characteristics?


Best wishes, Professor Bizzt
 
I found the service bulletin and it appears that the original tonearm unit, the YA-27 was replaced with the newer tonearm unit, the YA-32. The bulletin talks of replacing the tonearm on units with serial numbers below 5011.

My PX-2 is serial # 04015 and thus has the YA-27 tonearm with the wormgear drive. There are actually two service bulletins, the second to correct a tracking error problem cause by two resistors that were changed in the first bulletin having too high a value and causing a tracking sensitivity problem. My scanner is attached to my other computer but I will scan the bullletins tomorrow and post them here.

However, it would seem from the bulletins if your PX-2 has a serial # higher than 5011 the YA-32 tonearm was a factory installation.
 
PX-2 Tonearm Drives? What's really original?

Great merrylander!! You are a real service to humanity!

Your information should keep everyone on track.

I still think we should understand that most of the time malfunctions manifest because of a lack of maintenance, not so much bad design, although that happens sometimes as well.


Best wishes, Professor Bizzt
 
Well Professor, it was a slow day so I scanned the technical bulletins, so here they are. Any problems reading some values drop me a line.

With regard to TB42H it occurs to me that if anyone has mistracking problems with a PX2 and the PX3 arm it might be a good idea to check the values of R8 and R9. The TBs are a year apart so there may have been units released into the field with the 150K ohm values rather than the 68K ohm value.
 
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Well merrylander, I think everyone should be happy now due to your expertise and we can put this one to bed.

Best wishes, Professor Bizzt
 
Just the facts Maam...

I wrote this just after Veggieman & Prof B's posts, but neglected to hit the send button til just now:

I started this because my experience has been that most PX2s have the all-belt drive system in spite of what is shown in Yamaha sales and service literature.
The primary purpose of this chat should be the collection of facts: what serial number tables now have what type of tonearm drive.
When submitting, please include both drive type/serial #-especially if it's easily available! (without prejudice, this means you Veggieman!)

"vintaggeman i own two px2's and two px3's. all of them except for one px2 has the later version tonearm.
i can't see why the earlier tone arm is more desirable?"

And, of course, the next question would be, does either arm setup have an advantage? And I agree w/Bizzt-opinions are unwanted-if you want to be in THAT discussion, please couch it in facts.
In fact, the first question (drive type) seems to be leading to the likelyhood that both types were original. If that's the case, I expect the 2dB lower noise spec is attributable to the much larger DD motor and platter of the PX2 compared to the PX3.
If the tonearm changed the spec, then the 80dB S/N spec published in all Yamaha literature would not be a fact!

If the tonearm drive contributes nothing to the noise level, I don't see any reason to prefer one to the other.
 
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