Home |
Search |
Today's Posts |
|
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. |
Reply |
|
LinkBack | Thread Tools | Display Modes |
#1
Posted to sci.electronics.repair
|
|||
|
|||
CD lens scratches
The platter shifted along the spinner motor shaft until the lens could touch
CDs so scratched CDs and presumably, as convex top side, scratched lens. Has never read the TOC with any sacrificial CDs of mine. I cannot turn the lens in the lens carrier but the scratches , under x30 , seem to be not linear as I'd expect but look like matted micro cotton wool, ie curvy. How is that possible from a spinning CD. Is it that the CD grabs the lens on its floppy suspension and twists the housing enough to produce curves. Is there some sort of home-chemistry optical conformal coating . Even if the coating works only when wet , just to confirm a lens problem out of interest. Not worth replacing the deck ,but has anyone robbed a lens from a scrapped different make/type of deck and transplanted an as-you-find-it lens ,only , to make a goer? |
#2
Posted to sci.electronics.repair
|
|||
|
|||
CD lens scratches
"N_Cook" wrote in message ... The platter shifted along the spinner motor shaft until the lens could touch CDs so scratched CDs and presumably, as convex top side, scratched lens. Has never read the TOC with any sacrificial CDs of mine. I cannot turn the lens in the lens carrier but the scratches , under x30 , seem to be not linear as I'd expect but look like matted micro cotton wool, ie curvy. How is that possible from a spinning CD. Is it that the CD grabs the lens on its floppy suspension and twists the housing enough to produce curves. Is there some sort of home-chemistry optical conformal coating . Even if the coating works only when wet , just to confirm a lens problem out of interest. Not worth replacing the deck ,but has anyone robbed a lens from a scrapped different make/type of deck and transplanted an as-you-find-it lens ,only , to make a goer? To answer the last question first, I have taken lenses from lasers on scrap decks on a number of occasions, and had a good degree of success. Most notably, with Pioneer lasers that are mounted upside down, and which the lenses regularly fall out of, and then are lost, presumably through ventilation slots. Some of course, are still rattling around inside the player, but often they are not. I have used lenses from whatever came to hand that was the right diameter and general shape - mostly lenses from Sony KSS series lasers. The 'trick' is to make sure that *all* glue is carefully removed from both the lens suspension, and the underside of the lens rim. The lens *must* lie absolutely flat before it is re-fixed. I do this by putting the tiniest drop of superglue on the end of a sharply pointed thin scalpel blade, and then - whilst holding the lens pressed down with a cotton bud - touch it to the edge. The superglue is 'wicked' into the gap by capillary action, and sets very quickly because the layer is so thin. Once it has set, I repeat for the gap 180 degrees away. Sometimes, although not always, it is necessary to perform a set-up of focus offset. This is, of course, possible with a Pioneer, as it has a full raft of adjustments available, and clear test points and procedures for setting them. On late generation players, that have no such adjustments, it may be more of a problem, although some have automatic in-software adjustments. On home chemistry for getting rid of the scratches, I have found that the oil in metal polish wadding - such as Duraglit - has a very similar refractive index to the plastic used to make CDs from. So much so that scratches - even deep ones - disappear like magic when the disc is first treated to a wipe of wadding, left to go white, and then polished up with a dry cloth. I have always assumed that the oil in the wadding 'fills' the scratches in. It actually lasts quite a long time. Might be worth trying this with your scratched lens ? As it is made from optically-clear plastic, I would guess that it will not be too dissimilar from that which is used to make the discs. On the nature of the scratches, I would be extremely disinclined to believe that this had been done by anything coming between the disc and lens. For a start, the 'wall' around the edge of most lenses is at least as tall as the convex centre of the lens, and possibly taller. I have known lasers to scratch the underside of a disc, but never come across corresponding damage back the other way. I would suspect that someone has either 'had a go' at cleaning the lens manually, using inappropriate technique and materials / chemicals, or possibly used one of those dreadful cleaning discs with bristles on the bottom ... Arfa |
#3
Posted to sci.electronics.repair
|
|||
|
|||
CD lens scratches
Arfa Daily wrote in message
... "N_Cook" wrote in message ... The platter shifted along the spinner motor shaft until the lens could touch CDs so scratched CDs and presumably, as convex top side, scratched lens. Has never read the TOC with any sacrificial CDs of mine. I cannot turn the lens in the lens carrier but the scratches , under x30 , seem to be not linear as I'd expect but look like matted micro cotton wool, ie curvy. How is that possible from a spinning CD. Is it that the CD grabs the lens on its floppy suspension and twists the housing enough to produce curves. Is there some sort of home-chemistry optical conformal coating . Even if the coating works only when wet , just to confirm a lens problem out of interest. Not worth replacing the deck ,but has anyone robbed a lens from a scrapped different make/type of deck and transplanted an as-you-find-it lens ,only , to make a goer? To answer the last question first, I have taken lenses from lasers on scrap decks on a number of occasions, and had a good degree of success. Most notably, with Pioneer lasers that are mounted upside down, and which the lenses regularly fall out of, and then are lost, presumably through ventilation slots. Some of course, are still rattling around inside the player, but often they are not. I have used lenses from whatever came to hand that was the right diameter and general shape - mostly lenses from Sony KSS series lasers. The 'trick' is to make sure that *all* glue is carefully removed from both the lens suspension, and the underside of the lens rim. The lens *must* lie absolutely flat before it is re-fixed. I do this by putting the tiniest drop of superglue on the end of a sharply pointed thin scalpel blade, and then - whilst holding the lens pressed down with a cotton bud - touch it to the edge. The superglue is 'wicked' into the gap by capillary action, and sets very quickly because the layer is so thin. Once it has set, I repeat for the gap 180 degrees away. Sometimes, although not always, it is necessary to perform a set-up of focus offset. This is, of course, possible with a Pioneer, as it has a full raft of adjustments available, and clear test points and procedures for setting them. On late generation players, that have no such adjustments, it may be more of a problem, although some have automatic in-software adjustments. On home chemistry for getting rid of the scratches, I have found that the oil in metal polish wadding - such as Duraglit - has a very similar refractive index to the plastic used to make CDs from. So much so that scratches - even deep ones - disappear like magic when the disc is first treated to a wipe of wadding, left to go white, and then polished up with a dry cloth. I have always assumed that the oil in the wadding 'fills' the scratches in. It actually lasts quite a long time. Might be worth trying this with your scratched lens ? As it is made from optically-clear plastic, I would guess that it will not be too dissimilar from that which is used to make the discs. On the nature of the scratches, I would be extremely disinclined to believe that this had been done by anything coming between the disc and lens. For a start, the 'wall' around the edge of most lenses is at least as tall as the convex centre of the lens, and possibly taller. I have known lasers to scratch the underside of a disc, but never come across corresponding damage back the other way. I would suspect that someone has either 'had a go' at cleaning the lens manually, using inappropriate technique and materials / chemicals, or possibly used one of those dreadful cleaning discs with bristles on the bottom ... Arfa Some useful stuff there. With a needle lifting the lens carrier it will rise to the level of the underlying deck, combined with some inertia in such a flimsey mechanism, I could quite see the lens hitting a CD that is erroneously spinning only just above that level. The scratches are otherwise in a neat circle around the central area of the lens only , so unlikely done by a hand. Duraglit sounds a bit drastic , doesn't it have jeweller's rouge or some abrasive in it? but as useless as it stands then nothing to loose , now to see if I can dislodge the lens without destroying the suspension frame |
#4
Posted to sci.electronics.repair
|
|||
|
|||
CD lens scratches
"N_Cook" wrote in message
... Arfa Daily wrote in message ... "N_Cook" wrote in message ... The platter shifted along the spinner motor shaft until the lens could touch CDs so scratched CDs and presumably, as convex top side, scratched lens. Has never read the TOC with any sacrificial CDs of mine. I cannot turn the lens in the lens carrier but the scratches , under x30 , seem to be not linear as I'd expect but look like matted micro cotton wool, ie curvy. How is that possible from a spinning CD. Is it that the CD grabs the lens on its floppy suspension and twists the housing enough to produce curves. Is there some sort of home-chemistry optical conformal coating . Even if the coating works only when wet , just to confirm a lens problem out of interest. Not worth replacing the deck ,but has anyone robbed a lens from a scrapped different make/type of deck and transplanted an as-you-find-it lens ,only , to make a goer? To answer the last question first, I have taken lenses from lasers on scrap decks on a number of occasions, and had a good degree of success. Most notably, with Pioneer lasers that are mounted upside down, and which the lenses regularly fall out of, and then are lost, presumably through ventilation slots. Some of course, are still rattling around inside the player, but often they are not. I have used lenses from whatever came to hand that was the right diameter and general shape - mostly lenses from Sony KSS series lasers. The 'trick' is to make sure that *all* glue is carefully removed from both the lens suspension, and the underside of the lens rim. The lens *must* lie absolutely flat before it is re-fixed. I do this by putting the tiniest drop of superglue on the end of a sharply pointed thin scalpel blade, and then - whilst holding the lens pressed down with a cotton bud - touch it to the edge. The superglue is 'wicked' into the gap by capillary action, and sets very quickly because the layer is so thin. Once it has set, I repeat for the gap 180 degrees away. Sometimes, although not always, it is necessary to perform a set-up of focus offset. This is, of course, possible with a Pioneer, as it has a full raft of adjustments available, and clear test points and procedures for setting them. On late generation players, that have no such adjustments, it may be more of a problem, although some have automatic in-software adjustments. On home chemistry for getting rid of the scratches, I have found that the oil in metal polish wadding - such as Duraglit - has a very similar refractive index to the plastic used to make CDs from. So much so that scratches - even deep ones - disappear like magic when the disc is first treated to a wipe of wadding, left to go white, and then polished up with a dry cloth. I have always assumed that the oil in the wadding 'fills' the scratches in. It actually lasts quite a long time. Might be worth trying this with your scratched lens ? As it is made from optically-clear plastic, I would guess that it will not be too dissimilar from that which is used to make the discs. On the nature of the scratches, I would be extremely disinclined to believe that this had been done by anything coming between the disc and lens. For a start, the 'wall' around the edge of most lenses is at least as tall as the convex centre of the lens, and possibly taller. I have known lasers to scratch the underside of a disc, but never come across corresponding damage back the other way. I would suspect that someone has either 'had a go' at cleaning the lens manually, using inappropriate technique and materials / chemicals, or possibly used one of those dreadful cleaning discs with bristles on the bottom ... Arfa Some useful stuff there. With a needle lifting the lens carrier it will rise to the level of the underlying deck, combined with some inertia in such a flimsey mechanism, I could quite see the lens hitting a CD that is erroneously spinning only just above that level. The scratches are otherwise in a neat circle around the central area of the lens only , so unlikely done by a hand. Duraglit sounds a bit drastic , doesn't it have jeweller's rouge or some abrasive in it? but as useless as it stands then nothing to loose , now to see if I can dislodge the lens without destroying the suspension frame I think the circular rim of the lens prevents this. The dome shape of the lens is still below the height of the outer rim, I_think_ I would just clean it and it's likely OK. Generally if a disc tilts, it scrapes the tray or some other part well before it can touch the lens assembly. Mark Z. |
#5
Posted to sci.electronics.repair
|
|||
|
|||
CD lens scratches
Mark Zacharias wrote in message
... "N_Cook" wrote in message ... Arfa Daily wrote in message ... "N_Cook" wrote in message ... The platter shifted along the spinner motor shaft until the lens could touch CDs so scratched CDs and presumably, as convex top side, scratched lens. Has never read the TOC with any sacrificial CDs of mine. I cannot turn the lens in the lens carrier but the scratches , under x30 , seem to be not linear as I'd expect but look like matted micro cotton wool, ie curvy. How is that possible from a spinning CD. Is it that the CD grabs the lens on its floppy suspension and twists the housing enough to produce curves. Is there some sort of home-chemistry optical conformal coating . Even if the coating works only when wet , just to confirm a lens problem out of interest. Not worth replacing the deck ,but has anyone robbed a lens from a scrapped different make/type of deck and transplanted an as-you-find-it lens ,only , to make a goer? To answer the last question first, I have taken lenses from lasers on scrap decks on a number of occasions, and had a good degree of success. Most notably, with Pioneer lasers that are mounted upside down, and which the lenses regularly fall out of, and then are lost, presumably through ventilation slots. Some of course, are still rattling around inside the player, but often they are not. I have used lenses from whatever came to hand that was the right diameter and general shape - mostly lenses from Sony KSS series lasers. The 'trick' is to make sure that *all* glue is carefully removed from both the lens suspension, and the underside of the lens rim. The lens *must* lie absolutely flat before it is re-fixed. I do this by putting the tiniest drop of superglue on the end of a sharply pointed thin scalpel blade, and then - whilst holding the lens pressed down with a cotton bud - touch it to the edge. The superglue is 'wicked' into the gap by capillary action, and sets very quickly because the layer is so thin. Once it has set, I repeat for the gap 180 degrees away. Sometimes, although not always, it is necessary to perform a set-up of focus offset. This is, of course, possible with a Pioneer, as it has a full raft of adjustments available, and clear test points and procedures for setting them. On late generation players, that have no such adjustments, it may be more of a problem, although some have automatic in-software adjustments. On home chemistry for getting rid of the scratches, I have found that the oil in metal polish wadding - such as Duraglit - has a very similar refractive index to the plastic used to make CDs from. So much so that scratches - even deep ones - disappear like magic when the disc is first treated to a wipe of wadding, left to go white, and then polished up with a dry cloth. I have always assumed that the oil in the wadding 'fills' the scratches in. It actually lasts quite a long time. Might be worth trying this with your scratched lens ? As it is made from optically-clear plastic, I would guess that it will not be too dissimilar from that which is used to make the discs. On the nature of the scratches, I would be extremely disinclined to believe that this had been done by anything coming between the disc and lens. For a start, the 'wall' around the edge of most lenses is at least as tall as the convex centre of the lens, and possibly taller. I have known lasers to scratch the underside of a disc, but never come across corresponding damage back the other way. I would suspect that someone has either 'had a go' at cleaning the lens manually, using inappropriate technique and materials / chemicals, or possibly used one of those dreadful cleaning discs with bristles on the bottom ... Arfa Some useful stuff there. With a needle lifting the lens carrier it will rise to the level of the underlying deck, combined with some inertia in such a flimsey mechanism, I could quite see the lens hitting a CD that is erroneously spinning only just above that level. The scratches are otherwise in a neat circle around the central area of the lens only , so unlikely done by a hand. Duraglit sounds a bit drastic , doesn't it have jeweller's rouge or some abrasive in it? but as useless as it stands then nothing to loose , now to see if I can dislodge the lens without destroying the suspension frame I think the circular rim of the lens prevents this. The dome shape of the lens is still below the height of the outer rim, I_think_ I would just clean it and it's likely OK. Generally if a disc tilts, it scrapes the tray or some other part well before it can touch the lens assembly. Mark Z. I can pull this lens suspension up and it stops with top of dome perhaps ..5mm above the underlying deck area and has no protection ring, add in some inertia to the kicks and and I'm pretty sure it would be hitting any CD once the platter had dropped on the motor spindle. I will try jigging/temporary ancjoring the lens into that posistion to work on, as to get to it otherwise looks as though you have to take the whole laser assembly apart or at least a number of set screws that are adjustments of some sort by the look of them. |
Reply |
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
Save up to 70% on all contact lens | Home Repair | |||
Electromagnetic Lens Repair | Electronics Repair | |||
Projection TV lens ? | Electronics Repair | |||
Need to adapt a fiber optic as a lens to a video camera lens,can anyone help me out? | Electronics | |||
lens fluid | Electronics Repair |