Hello everyone,
I’m encountering an issue with my Pioneer PD-91 CD player. When it is flat, the disc doesn’t spin when I press "play," only a slight movement is visible. However, as soon as I place the player on its side (about a 45° angle), the disc starts spinning normally and playback works perfectly. Once the disc has started, I can place the player flat again, and it continues to work perfectly without any issues 😕.
I’ve cleaned the lens, but the problem persists. Could this indicate that the PWY 1004 laser is dead, or could it be another issue (spindle motor, alignment, clamp mechanism, etc.)?
I would love to hear if anyone has experienced a similar problem and if you have suggestions on any adjustments I could make to improve the situation. Are there any settings or simple repairs I could try before concluding that the laser is faulty?
Thank you in advance for any advice and feedback!
I’m encountering an issue with my Pioneer PD-91 CD player. When it is flat, the disc doesn’t spin when I press "play," only a slight movement is visible. However, as soon as I place the player on its side (about a 45° angle), the disc starts spinning normally and playback works perfectly. Once the disc has started, I can place the player flat again, and it continues to work perfectly without any issues 😕.
I’ve cleaned the lens, but the problem persists. Could this indicate that the PWY 1004 laser is dead, or could it be another issue (spindle motor, alignment, clamp mechanism, etc.)?
I would love to hear if anyone has experienced a similar problem and if you have suggestions on any adjustments I could make to improve the situation. Are there any settings or simple repairs I could try before concluding that the laser is faulty?
Thank you in advance for any advice and feedback!
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Check all the Alignments.
The Focus Offset could be out.
Worth checking the Mechanical alignments of the Laser, the beautiful thing with Pioneer Lasers of this age is that everything is align-able.
The results should tell you if the Laser is worn. The age of the Player may mean that it is :-(
P.
The Focus Offset could be out.
Worth checking the Mechanical alignments of the Laser, the beautiful thing with Pioneer Lasers of this age is that everything is align-able.
The results should tell you if the Laser is worn. The age of the Player may mean that it is :-(
P.
They are known for the laser lens to become unglued. Reglue and let set if it has. The other big one is a bad spindle motor, but table height is critical.
DO NOT ADJUST ANYTHING !!!!!!! It once worked adjusted as it is. Do not mess with it.
DO NOT ADJUST ANYTHING !!!!!!! It once worked adjusted as it is. Do not mess with it.
I have seen loose ones. The ones upside down generally dropped due to being run over a hotter component. If you were lucky the lens was stuck in the grease somewhere. Clean and glue it back in normally saved the head.
I have not seen many heads where the laser was bad. My memory is foggy, but if the laser current is marked on the head or cable, measure the Iop. You're allowed 10% increase - then it is at end of life.
Just check the disc table is clean. I would be looking at the RF pattern first if you got it running. Only then would adjustments be attempted. So you need a good oscilloscope that will show a clear eye pattern, 0.5 uS/div and about 0.5V/div vertical. If you don't have this instrument, then just stop. You are completely unable to do anything without a good oscilloscope. Note most digital scopes do not show a clear eye pattern.
I have not seen many heads where the laser was bad. My memory is foggy, but if the laser current is marked on the head or cable, measure the Iop. You're allowed 10% increase - then it is at end of life.
Just check the disc table is clean. I would be looking at the RF pattern first if you got it running. Only then would adjustments be attempted. So you need a good oscilloscope that will show a clear eye pattern, 0.5 uS/div and about 0.5V/div vertical. If you don't have this instrument, then just stop. You are completely unable to do anything without a good oscilloscope. Note most digital scopes do not show a clear eye pattern.
Also early Sony Mobile Audio Cd player mechs...oooofff going back in time....what ever you do to that Pioneer don't touch the 'grating adjustment' if at all possible
I have the diffraction grating adjust tools for many heads. A real pain, touchy. A technician's hell if he does a good job. Messed up a lot of CDs doing this. If the head is running - do not touch this!
I remember most heads were okay out of the box, but Pioneer heads never were. Yamaha was another.
I remember most heads were okay out of the box, but Pioneer heads never were. Yamaha was another.
Thanks for your answers !
I've followed the test mode procedures, and everything is responding correctly. The spindle motor starts perfectly even when the player is flat, so I can rule out the motor as the issue.
I've completely disassembled the player and found nothing unusual mechanically. The disc table appears to be aligned, and all the components are properly lubricated. There are no obstructions or issues with the movement.
At this point, should I proceed with more advanced tests, like adjusting the laser, or should I continue investigating the mechanical side? I’m wondering if the laser needs adjustment despite the motor and mechanical elements seeming fine.
sm : https://docs.stoneset.fr/ELECTRICAL_AUDIO/PIONEER/pd-91_sm.pdf
I've followed the test mode procedures, and everything is responding correctly. The spindle motor starts perfectly even when the player is flat, so I can rule out the motor as the issue.
I've completely disassembled the player and found nothing unusual mechanically. The disc table appears to be aligned, and all the components are properly lubricated. There are no obstructions or issues with the movement.
At this point, should I proceed with more advanced tests, like adjusting the laser, or should I continue investigating the mechanical side? I’m wondering if the laser needs adjustment despite the motor and mechanical elements seeming fine.
sm : https://docs.stoneset.fr/ELECTRICAL_AUDIO/PIONEER/pd-91_sm.pdf
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Run through the diagnostic procedure. The lens should do a focus search. DO NOT ADJUST THE LASER CURRENT !! if you do, just throw the machine out. A new laser head must be set up, the diffraction grating is out. A new head will not even read a disc. Either that or take it to a good tech who used to service them. They need the diffraction grating tool, and the experience to align them.
We have other tools, like laser power meters and equipment that allow us to check far more deeply. I've seen people who will not pay someone (for whatever reason) that destroy a machine over what was a simple fault. This goes for all equipment.
We have other tools, like laser power meters and equipment that allow us to check far more deeply. I've seen people who will not pay someone (for whatever reason) that destroy a machine over what was a simple fault. This goes for all equipment.
that laser lens looks collapsed to me...If I remember correctly the lens should be flush/level with the surround black plastic cover...a quick test is with a cotton bud just lightly depress the lens, if it bottoms out that's no good, if it moves a fair bit and bounces back probably ok
I had to wash the spindle motors in alcohol a few times... unsolder the spindle motor, place it in a jar filled with methylated spirit, close it, and shake (but don't stir... ha!). That will wash the deposits that are shorting the commutator segments, which in turn causes a loss of start-up torque.
I also used a syringe with a needle, which I inserted into the two small holes - check the spindle motor.... you'll see them. Then I injected the alcohol right onto the commutator. That also worked.
I also used a syringe with a needle, which I inserted into the two small holes - check the spindle motor.... you'll see them. Then I injected the alcohol right onto the commutator. That also worked.
With no Power applied, I think that Lens looks OK.
As I said earlier, check the Focus Offset adjustment. This adjusts the position (height, if you like) that the Lens sits at.
No-where in my earlier post did I say Adjust anything. I said CHECK the Alignments.
The 'Laser Power' was a valid adjustment for Pioneers and had to be done on all new Lasers.
All this is in the Service Manual which is available, free, on-line.
Hi-Fi Engine etc etc .
P.
As I said earlier, check the Focus Offset adjustment. This adjusts the position (height, if you like) that the Lens sits at.
No-where in my earlier post did I say Adjust anything. I said CHECK the Alignments.
The 'Laser Power' was a valid adjustment for Pioneers and had to be done on all new Lasers.
All this is in the Service Manual which is available, free, on-line.
Hi-Fi Engine etc etc .
P.
Hi percival007,
Normally you do not touch laser power unless you know exactly what you are doing. Increasing laser power improperly you may reach a point where it stops working ... forever. The unit worked with the adjustments the way they were unless someone else decided to play technician. Therefore, the adjustments are normally the last thing you touch, never the first. Most people twist controls first. That's all I am saying.
Yes, follow the manual and check the alignment. Some machines like Philips units do have you adjust the laser power, the Nakamichi OMS 5/7 are also like that. Most tell you not to touch laser power, and you should have a laser power meter even if the manual doesn't ask for one. Check the existing output against what is normal before increasing anything, and measure the laser current.
Normally you do not touch laser power unless you know exactly what you are doing. Increasing laser power improperly you may reach a point where it stops working ... forever. The unit worked with the adjustments the way they were unless someone else decided to play technician. Therefore, the adjustments are normally the last thing you touch, never the first. Most people twist controls first. That's all I am saying.
Yes, follow the manual and check the alignment. Some machines like Philips units do have you adjust the laser power, the Nakamichi OMS 5/7 are also like that. Most tell you not to touch laser power, and you should have a laser power meter even if the manual doesn't ask for one. Check the existing output against what is normal before increasing anything, and measure the laser current.
Again, where have I said adjust anything?
CHECK the alignments.
If you check the Focus Offset adjustment and find it's not 0.V D.C. @ TP1 Pin 6, then an attempt to adjust it should be made, according to the Service Manual.
If it's not possible to adjust to 0.V D.C. then you can look for the reason. Defective Focus Drive I.C. or associated components perhaps.
Or yes, even a collapsing Lens support.
In the Test Mode, monitoring the eye pattern, an adjustment can also be made to the Focus Offset to obtain the best quality 'eye pattern'. If the Lens support is weak, then adjusting away from 0.V D.C. in Stop Mode may be the only answer to the O.P.'s problem. Rather than swapping the Laser out, if one can be found.
Pioneer always 'allowed' Laser Power adjustment on their Players. Point 9 in the Adjustment section details what to measure for and how and what to adjust. In this case it's a pk-pk measurement of the R.F. waveform.
Yes, other Manufacturers were different from this, but I believe the original post was about a Pioneer !
CHECK the alignments.
If you check the Focus Offset adjustment and find it's not 0.V D.C. @ TP1 Pin 6, then an attempt to adjust it should be made, according to the Service Manual.
If it's not possible to adjust to 0.V D.C. then you can look for the reason. Defective Focus Drive I.C. or associated components perhaps.
Or yes, even a collapsing Lens support.
In the Test Mode, monitoring the eye pattern, an adjustment can also be made to the Focus Offset to obtain the best quality 'eye pattern'. If the Lens support is weak, then adjusting away from 0.V D.C. in Stop Mode may be the only answer to the O.P.'s problem. Rather than swapping the Laser out, if one can be found.
Pioneer always 'allowed' Laser Power adjustment on their Players. Point 9 in the Adjustment section details what to measure for and how and what to adjust. In this case it's a pk-pk measurement of the R.F. waveform.
Yes, other Manufacturers were different from this, but I believe the original post was about a Pioneer !
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Hi percival007,
Settle down man! I always reply knowing many lurkers read these posts. I reply in a general sense, I did not claim you advised to adjust anything.
As for laser power adjustment. Yes, I know. However, I found it wise to measure the output directly to avoid increasing it too far due to another problem and causing the laser diode to fail. There is always a good case to be cautious.
So how many CD players have you found where the laser power was turned down? Not many I bet. Therefore, increasing the laser power will only hasten the failure. I serviced many where the previous dude increased the laser power only to have the machine fail months later. The customer only knows it was just in to that shop, and they are not happy. So being practical, you want to see if the output is normal, and the current draw is normal for that individual head. You can call an end of life laser quickly that way. One machine in particular only needed the lens cleaned, but had run really high for a few months.
Remember. All kinds of people read these posts, then figure they can "fix" a machine belong to a friend or their own. That is where I am coming from.
Settle down man! I always reply knowing many lurkers read these posts. I reply in a general sense, I did not claim you advised to adjust anything.
As for laser power adjustment. Yes, I know. However, I found it wise to measure the output directly to avoid increasing it too far due to another problem and causing the laser diode to fail. There is always a good case to be cautious.
So how many CD players have you found where the laser power was turned down? Not many I bet. Therefore, increasing the laser power will only hasten the failure. I serviced many where the previous dude increased the laser power only to have the machine fail months later. The customer only knows it was just in to that shop, and they are not happy. So being practical, you want to see if the output is normal, and the current draw is normal for that individual head. You can call an end of life laser quickly that way. One machine in particular only needed the lens cleaned, but had run really high for a few months.
Remember. All kinds of people read these posts, then figure they can "fix" a machine belong to a friend or their own. That is where I am coming from.
Never understood why 'techs' want to adjust laser power...and overlook all the basics of CD player repair
Focus offset wont be correct and wont adjust correctly if the suspension has collapsed, have never seen/heard of a defective focus servo IC
The original poster noted the unit will read the disc when unit is on an angle, this symptom points to a mechanical issue I bet it works when ok its upside down...anyway just the opinions of service engineer of 30 plus years of experience 🤓
Focus offset wont be correct and wont adjust correctly if the suspension has collapsed, have never seen/heard of a defective focus servo IC
The original poster noted the unit will read the disc when unit is on an angle, this symptom points to a mechanical issue I bet it works when ok its upside down...anyway just the opinions of service engineer of 30 plus years of experience 🤓