PIONEER PD-91 CD Player - how to dial in for CD-R playback

Master Tasuke

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thought i'd start a dedicated thread on how to enable the vintage classic PIONEER ELITE series
PD-91, PIONEER's very first ELITE series CDP, to more reliably read CD-Rs.

((NOTE; the PD-91 is a notoriously finicky CDP in regards to CD-Rs, and, even after this adjustment, it can be rather crotchety about them, apparently due to CD-R brand/reflectivity/CD Burner/ETC. as such, while this adjustment IS absolutely beneficial to the PD-91's CD-R read tolerances, it IS NOT, unfortunately, a cure-all that will enable the player to read everything you throw at it. in fact, the player will often take 30secs./1min. to read the TOC, and/or sync to a track and begin play,
on many CD-Rs. others, it will read just fine, usually taking just a wee bit longer to sync up than it would reading a garden variety Redbook factory CD. in fact, this adjustment speeds up the players
handling of factory CDs, to the degree where the player will nominally read TOC and/or begin playback in less than a 1/2 second. just remember that this is a fussy machine, for whatever reason, with homegrown CD-Rs, and that your personal mileage will most likely vary with your copy
of this magnificent, yet temperamental machine...))


- PD-91, with top aluminum panel removed -

((NOTE, unless you have modded this player as i have, and bummed the alum top plate from
from either the Japanese market PD-3000, or -5000, or from the U.S. PD-93,
then your U.S. and/or EURO/WORLD version PD-91 will require removal
of 16 screws, both rosewood panels, and the pressed sheet metal top bonnet
in order to gain access to the player interior))


PD-91CD-RAdjustment10-29-111.jpg



now then. there is a series of Variable Potentiometers on the section of PCB directly aft
of the disc transport cage/assy;

PD-91CD-RAdjustment10-29-112.jpg


PD-91CD-RAdjustment10-29-113.jpg



there are only TWO of these that you want to mess around with.
VR-3 and VR-4, FOCUS GAIN and TRACKING GAIN, respectively.

BOTH are located at the far right, right beside the black-anodized heatsink
vertically mounted on the central stay/DIGITAL section shield;

PD-91CD-RAdjustment10-29-114.jpg


you will want to adjust these, counter-clockwise, to the positions shown
in that photo directly above.

do this, while attempting to play a CD-R. it should sync/read the disc at those positions
illustrated above. if not, then load another CD-R until it is successfully read.

further adjustment MAY be necessary, if your 91's laser pick-up is tiring out.
in fact, if it is too heavily worn, it may not read ANY CD-R, even if it still spins
factory discs just fine. as always, your personal mileage may vary.


also, please bear in mind that i am NOT a skilled Technician.
i have no electronic service education whatsoever, and this advice is wholly based
on my limited personal self-taught experience.

that said, someone reading this out there just might know how to dial this player
in for smooth CD-R operation better then i do, and may have had better success with it than
me. if that person is out there, then, please, by all means, contribute to this thread...


PD-91JOHN5-29-112.jpg


PD-91Accs6-20-11.jpg
 
Re: PIONEER PD-91 CD Player - how to dial in for CD-R playba

John, you are amazing in your qwest to overcome any quirks that a nice piece of Pioneer gear can have, and you do it naturally, great fix it thread on a tuely wonderful deck!! :thumbright:
 
Re: PIONEER PD-91 CD Player - how to dial in for CD-R playba

Knowing what I do about CD alignment, your "method" is not repeatable, and can introduce problems into the unit that affect playability. Yes, if focus gain is too high, the focus servo will overreact to low reflectivity discs. If someone wants to play with this control, no bad effects will occur, but be sure you mark the control so you can return tot he original setting!
Tracking gain dictates behavior in TOC, but more importantly, the tracking behavior with scratched discs. Altering this to play a CD-R may introduce skipping and search problems.
The real problem is that the RF level is low with CD-R playback. The only DIY I recommend is cleaning the laser lens with a dry Qtip.
 
Re: PIONEER PD-91 CD Player - how to dial in for CD-R playba

And I say it's time to replace your LASER DIODE. They have a lifespan and the read mechanisn must be repaired eventually.

DVD is even worse...to allow for CD compatibility TWO DIODES must be used.

I have 2 5-disc carousels c.1999 or so that define Jack Sprat perfectly,,,one could play no compact discs and one hates DVDs.

Wait until you look into a really old Laserdisc player, big 'laser' unit and all.
 
Re: PIONEER PD-91 CD Player - how to dial in for CD-R playba

Some middle generation CD players have trouble with CD-Rs, and it is not always a function of laser power. The focus and tracking servos are tuned to a resonant frequency. Somehow the CD-Rs cause these servos to move ouside their designed comfort zones.
 
Re: PIONEER PD-91 CD Player - how to dial in for CD-R playba

I used my old PD-91 for CD-R playback early on, around 1994 or 1995, and it worked fine. My opinion is that the problem you have is that the pickups go bad over time in terms of alignment and mechanical performance. I'm not convinced that they can be easily fixed; this is like an car transmission going bad. The engine may be fine, and the brakes work, but if the transmission is bad, the car ain't gonna move.

This is a problem with tons of 20-year-old CD players, not just this one.



well, i'm QUITE happy now... :)

just last night, i opened her up again, and decided to take a careful inspection of the transport assembly.

i removed the stabilizer cage, and ejected the disc tray, before POWER OFF.
i went to inspect the LD pickup on it's floating electromagnetic linear motor mount, and... SOMETHING just did not look right about it.

so, i went and undid the small PHILLIPS head screw and HEX-head bolt
that holds the short shaft in place, that slides through a hole in the
pickup body, and mounts into lugs on the linear motor's pickup mounting cradle, and removed the pickup from the player chassis.

after inspecting it some, i carefully reinstalled it, making sure
that it was firmly and correctly in place, and tightly locked it down
with the copper retaining plate held in place by that PHILLIPS and HEX.

i test it out, and, lo-and-behold, IT READS CD-Rs... every bit as fast (1/2 sec. or less) as it does factory discs!!

in fact, i go into an orgy of CD-R pulling right on the spot,
AND IT READS/PLAYS EVERY ONE OF THEM... in a 1/2sec. or less!!


i think i just solved the problem.

that copper retaining plate i mentioned, that secures the pickup
retaining shaft in place, was not secured tightly when i first got to it, (the PHILLIPS screw was fine, but the HEX-bolt was loose)
and, if the LDP, as a result, wasn't thrown out of place at some time in it's past,
then it evidently amost certainly was, during shipment to my OREGON home, from the original seller, down in TEXAS.

evidently, i can only assume,
the pick-up was poorly installed in the factory, or, much more likely,
a replacement was sloppily installed by a careless service tech
at some time in this player's history.

apparently, that threw off the alignment of the pick-up
to where it had tre greatest difficulty handling CD-Rs...
though it did not seem to affect the handling of factory discs,
i suppose since they are so much easier for any optical drive to read.


at any rate, it does not seem that the seller of this player, the self-proclaimed original owner, lied to me after all,
and that this player WAS seldom used... at least since it's last LD pick-up replacement... if it actually ever had one, that is...


nakdoc said:
Knowing what I do about CD alignment, your "method" is not repeatable, and can introduce problems into the unit that affect playability... The only DIY I recommend is cleaning the laser lens with a dry Qtip.



i greatly respect and appreciate your experienced advice.

as outlined above, my 91 will now read just about everything i load into it, all within it's specified 1/2 sec. or less. further, i've noticed that the pickup is quieter
in it's operation then before.

this is all good, is it not? any risks? anything i should be watching out for?
 
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