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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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Pioneer PDM450 laser help
howdy, I have a pioneer PD-M450 Cd player that would not play disks. It
would load them but and the laser would go in try to focus but the disk would never spin. I found the plastic lens had fallen out of the optical assembly and would not stay in when replaced. I ordered a new optical pickup and replaced the old one. I have the same problem. I have confirmed that the spindle motor will run with 1.0 vdc supplied. I do not see any voltage appear at the motor leads while the lens is trying to focus. Please help, optical pickup was $$$$. thanks, Gary |
#2
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Pioneer PDM450 laser help
On Thu, 04 Jun 2009 10:20:49 -0400, "Gary L. Woodruff"
wrote: howdy, I have a pioneer PD-M450 Cd player that would not play disks. It would load them but and the laser would go in try to focus but the disk would never spin. I found the plastic lens had fallen out of the optical assembly and would not stay in when replaced. I ordered a new optical pickup and replaced the old one. I have the same problem. I have confirmed that the spindle motor will run with 1.0 vdc supplied. I do not see any voltage appear at the motor leads while the lens is trying to focus. Please help, optical pickup was $$$$. thanks, Gary I have heard that you can glue the lens back in, but I've never had one to try that with. The new optical pickup probably needs a complete alignment. You'll need the service manual, oscilloscope, and other test equipment. Andy Cuffe |
#3
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Pioneer PDM450 laser help
"Gary L. Woodruff" wrote in message ... howdy, I have a pioneer PD-M450 Cd player that would not play disks. It would load them but and the laser would go in try to focus but the disk would never spin. I found the plastic lens had fallen out of the optical assembly and would not stay in when replaced. I ordered a new optical pickup and replaced the old one. I have the same problem. I have confirmed that the spindle motor will run with 1.0 vdc supplied. I do not see any voltage appear at the motor leads while the lens is trying to focus. Please help, optical pickup was $$$$. thanks, Gary Did you remove the safety short on the pickup assembly? It is normally two pads joined with a blob of solder you need to remove. This stops the pickup being damaged by static, and should be removed once the pickup is in place. The assembly will have no output with this short in place. Gareth. |
#4
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Pioneer PDM450 laser help
Andy Cuffe writes:
On Thu, 04 Jun 2009 10:20:49 -0400, "Gary L. Woodruff" wrote: howdy, I have a pioneer PD-M450 Cd player that would not play disks. It would load them but and the laser would go in try to focus but the disk would never spin. I found the plastic lens had fallen out of the optical assembly and would not stay in when replaced. I ordered a new optical pickup and replaced the old one. I have the same problem. I have confirmed that the spindle motor will run with 1.0 vdc supplied. I do not see any voltage appear at the motor leads while the lens is trying to focus. Please help, optical pickup was $$$$. thanks, Gary I have heard that you can glue the lens back in, but I've never had one to try that with. The new optical pickup probably needs a complete alignment. You'll need the service manual, oscilloscope, and other test equipment. I've glued the lenses back a couple of times. Use 5 minute Epoxy, NOT superglue. Just make sure it seats as far as it will (gently) go. I was impressed how easily this could be done on something that has to focus to a couple microns! -- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/ Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/ +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm | Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html Important: Anything sent to the email address in the message header above is ignored unless my full name AND either lasers or electronics is included in the subject line. Or, you can contact me via the Feedback Form in the FAQs. |
#5
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Pioneer PDM450 laser help
Gary L. Woodruff wrote:
howdy, I have a pioneer PD-M450 Cd player that would not play disks. It would load them but and the laser would go in try to focus but the disk would never spin. I found the plastic lens had fallen out of the optical assembly and would not stay in when replaced. I ordered a new optical pickup and replaced the old one. I have the same problem. I have confirmed that the spindle motor will run with 1.0 vdc supplied. I do not see any voltage appear at the motor leads while the lens is trying to focus. Please help, optical pickup was $$$$. thanks, Gary The replacement pickup may not work right out of the box because IIRC, it doesn't come pre-aligned. You'll need to boot it into test mode and use a scope probe to adjust it. I believe it's called the gradient adjustment. Might just be easier to do as the previous responders have suggested which is to carefully glue the lens back on. Make sure whatever glue you use, that it doesn't fog up the lens! -- David Farber David Farber's Service Center L.A., CA |
#6
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Pioneer PDM450 laser help
"David Farber" wrote in message
. .. Gary L. Woodruff wrote: howdy, I have a pioneer PD-M450 Cd player that would not play disks. It would load them but and the laser would go in try to focus but the disk would never spin. I found the plastic lens had fallen out of the optical assembly and would not stay in when replaced. I ordered a new optical pickup and replaced the old one. I have the same problem. I have confirmed that the spindle motor will run with 1.0 vdc supplied. I do not see any voltage appear at the motor leads while the lens is trying to focus. Please help, optical pickup was $$$$. thanks, Gary The replacement pickup may not work right out of the box because IIRC, it doesn't come pre-aligned. You'll need to boot it into test mode and use a scope probe to adjust it. I believe it's called the gradient adjustment. Might just be easier to do as the previous responders have suggested which is to carefully glue the lens back on. Make sure whatever glue you use, that it doesn't fog up the lens! -- David Farber David Farber's Service Center L.A., CA It would probably still "try" to play the disc... I think the shorting pad is on the flat wire which plugs into the circuit board. Regarding the grating adjustment: it does require a 'scope and some care with the physical adjustment. What looks like an adjustment potentiometer is actually a small slider to be actuated only a small amount one way or the other by your screwdriver. Turn it like a pot and it falls apart. Learned this one the hard way! The adjustment procedure in the old manuals was a bit of "purple magic". After all what is a "smooth null" in the waveform anyway? Fortunately it's really easier than that... In test mode, and with the disc spinning, servos open, and observing the HF pattern, adjust the eye pattern for max, then press the Pause button to close the tracking servo. If the adjustment is off, the size of the waveform will drop. Re-adjust a bit to one side or the other until the size of the waveform is the same whether the servo is closed or not. This is how the Pioneer guys do it (or did anyway before they all got laid off). Mark Z. |
#7
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Pioneer PDM450 laser help
I have serviced CD players, but not your model type. Most of the time,
you can glue the plastic lens back in to its proper position. You put some epoxy around the sides. Make sure that the optical path is not obstructed with the epoxy. Now that you replaced the head assembly, it will require a complete alignment of both the electronics and the mechanical. To do this you will require the service manual, scope, DVM, calibration disks, and most likely some training. Normaly, unless a CD player is a current model, and it is an expensive very high end type, I tell people to buy a new one rather than sink money in to it. Jerry G. On Jun 4, 10:20*am, "Gary L. Woodruff" wrote: howdy, I have a pioneer PD-M450 Cd player that would not play disks. It would load them but and the laser would go in try to focus but the disk would never spin. I found the plastic lens had fallen out of the optical assembly and would not stay in when replaced. I ordered a new optical pickup and replaced the old one. I have the same problem. I have confirmed that the spindle motor will run with 1.0 vdc supplied. I do not see any voltage appear at the motor leads while the lens is trying to focus. Please help, optical pickup was $$$$. thanks, Gary |
#8
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Pioneer PDM450 laser help
"David Farber" wrote in message . .. Gary L. Woodruff wrote: howdy, I have a pioneer PD-M450 Cd player that would not play disks. It would load them but and the laser would go in try to focus but the disk would never spin. I found the plastic lens had fallen out of the optical assembly and would not stay in when replaced. I ordered a new optical pickup and replaced the old one. I have the same problem. I have confirmed that the spindle motor will run with 1.0 vdc supplied. I do not see any voltage appear at the motor leads while the lens is trying to focus. Please help, optical pickup was $$$$. thanks, Gary The replacement pickup may not work right out of the box because IIRC, it doesn't come pre-aligned. You'll need to boot it into test mode and use a scope probe to adjust it. I believe it's called the gradient adjustment. Might just be easier to do as the previous responders have suggested which is to carefully glue the lens back on. Make sure whatever glue you use, that it doesn't fog up the lens! -- David Farber David Farber's Service Center L.A., CA Yep, 100%. Aligning these pickups is a mother of a job that requires a special small disc to allow access to the diffraction grating adjustment screw in the top of the laser. The delicacy of this adjustment, and the ridiculous level of accuracy required, makes me defy anyone to get this adjustment exactly 'right', without factory conditions, and a high skill level of working with CD players. Note also what someone else said about the laser diode shorting points. They are on the orange flexiprint connection tail, by the tiny laser power set pot. They come with a blob of solder across them. The 'fallen out lens syndrome' is very common, and is always repairable. The trick to getting it to always work out ok, is to first spend some time with a sharp and tiny-bladed modeller's scalpel, removing *every trace* of the original glue from *both* the lens seat, and the rim of the lens itself. The lens can then be refitted, and held square in the carrier with tweezers exerting slight pressure on opposite sides. Rapid cure two part epoxy that you've already mixed, can then be applied to four spots around the lens edge, using the tip of a darning needle. After the glue has thoroughly set, any slight optical misalignment can be easily taken out using the raft of controls available on Pioneers (tracking offset / balance / gain, focus offset / balance / gain). All of these can be set easily using a 'scope to observe the eye pattern at TP1. Sorry to be negative about your new and expensive pickup, but honestly, you *will* struggle to ever get it going. Just as a further slight downer, these pickups must be amongst the most reliable ever made and used by any manufacturer. Since CD players first appeared in the 80s, I would say that I have replaced no more than five of these, that were genuinely faulty. The other very common problem on these players, that inexperienced people often mis-diagnosed as a bad laser, was a defective spindle motor. Sometimes, a bad motor would try to rotate the disc, and squeal horribly in the attempt ... Arfa |
#9
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Pioneer PDM450 laser help
"David Farber" wrote in message . .. Gary L. Woodruff wrote: howdy, I have a pioneer PD-M450 Cd player that would not play disks. It would load them but and the laser would go in try to focus but the disk would never spin. I found the plastic lens had fallen out of the optical assembly and would not stay in when replaced. I ordered a new optical pickup and replaced the old one. I have the same problem. I have confirmed that the spindle motor will run with 1.0 vdc supplied. I do not see any voltage appear at the motor leads while the lens is trying to focus. Please help, optical pickup was $$$$. thanks, Gary The replacement pickup may not work right out of the box because IIRC, it doesn't come pre-aligned. You'll need to boot it into test mode and use a scope probe to adjust it. I believe it's called the gradient adjustment. Might just be easier to do as the previous responders have suggested which is to carefully glue the lens back on. Make sure whatever glue you use, that it doesn't fog up the lens! -- David Farber David Farber's Service Center L.A., CA Yep, 100%. Aligning these pickups is a mother of a job that requires a special small disc to allow access to the diffraction grating adjustment screw in the top of the laser. The delicacy of this adjustment, and the ridiculous level of accuracy required, makes me defy anyone to get this adjustment exactly 'right', without factory conditions, and a high skill level of working with CD players. Note also what someone else said about the laser diode shorting points. They are on the orange flexiprint connection tail, by the tiny laser power set pot. They come with a blob of solder across them. The 'fallen out lens syndrome' is very common, and is always repairable. The trick to getting it to always work out ok, is to first spend some time with a sharp and tiny-bladed modeller's scalpel, removing *every trace* of the original glue from *both* the lens seat, and the rim of the lens itself. The lens can then be refitted, and held square in the carrier with tweezers exerting slight pressure on opposite sides. Rapid cure two part epoxy that you've already mixed, can then be applied to four spots around the lens edge, using the tip of a darning needle. After the glue has thoroughly set, any slight optical misalignment can be easily taken out using the raft of controls available on Pioneers (tracking offset / balance / gain, focus offset / balance / gain). All of these can be set easily using a 'scope to observe the eye pattern at TP1. Sorry to be negative about your new and expensive pickup, but honestly, you *will* struggle to ever get it going. Just as a further slight downer, these pickups must be amongst the most reliable ever made and used by any manufacturer. Since CD players first appeared in the 80s, I would say that I have replaced no more than five of these, that were genuinely faulty. The other very common problem on these players, that inexperienced people often mis-diagnosed as a bad laser, was a defective spindle motor. Sometimes, a bad motor would try to rotate the disc, and squeal horribly in the attempt ... Arfa |
#10
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Pioneer PDM450 laser help
First the server wouldn't upload the message at all, now it's done it twice.
Good old Virgin ... !! Arfa |
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