Hi,
I am new to this forum and thus far, though I searched tis forum, I seem not to be able to find a solution to my problem. Sorry if I'm asking a question that has been answered somewhere.
After replacing the KSS210A laser unit in my Denon DCD1420 I am able to play CDs, but there is an annoying whining, which seems to stem rom the laser unit and after sone time the CD player goes berserk.
Anyone ideas on what this might be, or what I can do about it?
Thanks
Willem
I am new to this forum and thus far, though I searched tis forum, I seem not to be able to find a solution to my problem. Sorry if I'm asking a question that has been answered somewhere.
After replacing the KSS210A laser unit in my Denon DCD1420 I am able to play CDs, but there is an annoying whining, which seems to stem rom the laser unit and after sone time the CD player goes berserk.
Anyone ideas on what this might be, or what I can do about it?
Thanks
Willem
Do you have an oscilloscope ? That's the only sure way to see what's going on, however,
Mark all the pots with a felt marker first, it's so easy to turn something by mistake.
Tracking gain and focus gain are surprisingly uncritical---- do not alter these yet. PLL critical adjustment but is not related to the pickup -- don't touch.
Tweak the Focus offset pot while it is playing. Set it where the "white" noise from the pickup is minimum. See what that does and report back.
Non of these pots will do any damage if they are turned incorrectly.
Mark all the pots with a felt marker first, it's so easy to turn something by mistake.
Tracking gain and focus gain are surprisingly uncritical---- do not alter these yet. PLL critical adjustment but is not related to the pickup -- don't touch.
Tweak the Focus offset pot while it is playing. Set it where the "white" noise from the pickup is minimum. See what that does and report back.
Non of these pots will do any damage if they are turned incorrectly.
Hi Willem,
Sounds like a defective head. When you turned the gain down, it was reduced too far. Return the control to the original position. You need another KSS-210A head.
Whatever you do, do not turn any more controls. You absolutely do require a 'scope to set these machines up. There is even a program built into the machine to make things easier. Since your machine is a really nice one, did you consider getting the service manual for it?
There is a clamp arm modification, I wonder if that's been done? The original is a pressure clamp system, the revised type is a magnetic clamp system. The arm decouples from the "puck" that holds the CD down on the turntable. There are other mods, but the arm change is normally done at the same time. Last I heard, those parts have been discontinued.
The E-F balance control setting is critical. Do not touch it unless you know exactly what you are doing.
If the arm modification has been done, this is an excellent player and well worth keeping. I would find a good audio technician who has a good reputation set this machine up. Look for a Denon warranty shop.
-Chris
Sounds like a defective head. When you turned the gain down, it was reduced too far. Return the control to the original position. You need another KSS-210A head.
Whatever you do, do not turn any more controls. You absolutely do require a 'scope to set these machines up. There is even a program built into the machine to make things easier. Since your machine is a really nice one, did you consider getting the service manual for it?
There is a clamp arm modification, I wonder if that's been done? The original is a pressure clamp system, the revised type is a magnetic clamp system. The arm decouples from the "puck" that holds the CD down on the turntable. There are other mods, but the arm change is normally done at the same time. Last I heard, those parts have been discontinued.
The E-F balance control setting is critical. Do not touch it unless you know exactly what you are doing.
If the arm modification has been done, this is an excellent player and well worth keeping. I would find a good audio technician who has a good reputation set this machine up. Look for a Denon warranty shop.
-Chris
Hi Willos,
As Anatech mentioned a 'scope is the only sure way to see whats happening.
The focus offset ( or bias ) adjustment on it's own is do-able, the point of minimum noise from the pickup should coincide with the correct setting. I used to find this time and again -- I alway use a scope but setting by ear ( I can see Chris cringeing at that - sorry Chris ) was, with experience just as good. For that one adjustment only I must add.
You mention the problem of sticking half way through the disc. That points to a mechanical issue really, maybe some gunge in the teeth of the sled motor or the rack on the pickup.
I would recheck the setting on that pot, turn it up to the point where the noise is just becoming audible and then back it off a degree or two.
Is there an EF balance pot ?? You didn't mention it at first- some players don't have the adjustment anyway- but as Anatech says that adjustment is super critical and a scope is definitely required for that one.
The one pot not to turn is the one on the pickup, the laser power.
Why did you replace the pickup anyway -- was it for the sticking problem ?
As Anatech mentioned a 'scope is the only sure way to see whats happening.
The focus offset ( or bias ) adjustment on it's own is do-able, the point of minimum noise from the pickup should coincide with the correct setting. I used to find this time and again -- I alway use a scope but setting by ear ( I can see Chris cringeing at that - sorry Chris ) was, with experience just as good. For that one adjustment only I must add.
You mention the problem of sticking half way through the disc. That points to a mechanical issue really, maybe some gunge in the teeth of the sled motor or the rack on the pickup.
I would recheck the setting on that pot, turn it up to the point where the noise is just becoming audible and then back it off a degree or two.
Is there an EF balance pot ?? You didn't mention it at first- some players don't have the adjustment anyway- but as Anatech says that adjustment is super critical and a scope is definitely required for that one.
The one pot not to turn is the one on the pickup, the laser power.
Why did you replace the pickup anyway -- was it for the sticking problem ?
Thanks for your quick replies.
Alas, I do not own a scope. My brother has an old one. I'll ask if it 's still in working condition. I tried my old 10 MHz single channel parallel port version yesterday, but the sofware did not run on my current PC.
@keyinkr: Indeed, it occurs halfway every disk I tried. I'll inspect the mechanical things tonight.
@anatech: It's a brandnew original head and I have been very cautious about static electricity and took all precautions.
I did not mod the clamp (or anything else), it's still spring-loaded.
Do you happen to know where to lay hand on the service manual?
Can you tell me where the mods you are refering to have been documented?
@Mooly: I will treat the offset pot as you suggest. There is no EF-balance as far as I can see. I replaced the KSS because the player refused to read more and more CD's, especially the home-brew variety.
Sorry for all my questions. And, being just a humble Dutchman, for my english.
Thanks and greetings,
Willem
Alas, I do not own a scope. My brother has an old one. I'll ask if it 's still in working condition. I tried my old 10 MHz single channel parallel port version yesterday, but the sofware did not run on my current PC.
@keyinkr: Indeed, it occurs halfway every disk I tried. I'll inspect the mechanical things tonight.
@anatech: It's a brandnew original head and I have been very cautious about static electricity and took all precautions.
I did not mod the clamp (or anything else), it's still spring-loaded.
Do you happen to know where to lay hand on the service manual?
Can you tell me where the mods you are refering to have been documented?
@Mooly: I will treat the offset pot as you suggest. There is no EF-balance as far as I can see. I replaced the KSS because the player refused to read more and more CD's, especially the home-brew variety.
Sorry for all my questions. And, being just a humble Dutchman, for my english.
Thanks and greetings,
Willem
It really does sound mechanical to me. Sled motors can play up. If you can disconnect the gears and disconnect the motor electrically it can be worth putting a 9 volt battery across it briefly to "clean up" any contamination on the commutator.
Might prove something doing that. Still sounds more like it's sticking really.
If you can connect a DVM across the motor while it's playing if the sled sticks the voltage across the motor should suddenly start to rise when the sled sticks.
Might prove something doing that. Still sounds more like it's sticking really.
If you can connect a DVM across the motor while it's playing if the sled sticks the voltage across the motor should suddenly start to rise when the sled sticks.
Could be as simple as cleaning and a re-lube of the sled track. The old lubricant can get sticky and cause erratic behaviour.
There's some threads around here on lubricants for the sled and gears. I use a Tamiya switch lubricant, others use auto transmission fluid, brake rubber grease. You are supposed to use something like Molykote EM-30L grease that's normally sold by the kilo at a zillion $$$$.
Don't use any oils that will evaporate or silicon products.
There's some threads around here on lubricants for the sled and gears. I use a Tamiya switch lubricant, others use auto transmission fluid, brake rubber grease. You are supposed to use something like Molykote EM-30L grease that's normally sold by the kilo at a zillion $$$$.
Don't use any oils that will evaporate or silicon products.
Hi Mooly,
I can set focus and tracking offsets by ear too. Focus is louder, but I certainly can't recommend someone starting out do this. Remember, shortcuts are for people who know well how to perform a task. We also know what to watch out for.
KSS-210A servos use an E-F balance adjustment normally. If they put fixed resistors in there, it needs a trimmer control. That adjustment is too critical to leave unadjusted and differs from head to head. Remember, it's the balance between the E and F photo diodes. Compensates for mechanical misalignment and efficiency differences.
Hi Willem,
The old scope is okay for looking at the servos, but the RF or EFM pattern requires 0.5 uS / Div for horizontal and 0.5 V / Div for vertical.
I do agree that it sounds like a tooth broken from the rack gear. Commonly if the owner (you) plays home burned CD's, the mech may get run to the end and break a tooth off. It gets into the grease and can not be seen easily. Remove the drive gear from between the rack and motor drive. Then see if your head moves smoothly back and forth. Clean everything off and inspect the gears, you may also have one cracked from the center out. Relubricate with white lithium grease. As little as possible!
The reason I condemned your new head is simple. One servo was oscillating and that is not right. Always remember that new does not mean good. I've had a few bad heads over the years. To be sure, use the 'scope to find the minimum low and high frequency servo noise. If the head oscillates there, it's bad.
Hi Peter,
Denon stopped using Molykote for these applications. They had some problems with it. I just do what I'm told like a good little techy!
-Chris
I can set focus and tracking offsets by ear too. Focus is louder, but I certainly can't recommend someone starting out do this. Remember, shortcuts are for people who know well how to perform a task. We also know what to watch out for.
KSS-210A servos use an E-F balance adjustment normally. If they put fixed resistors in there, it needs a trimmer control. That adjustment is too critical to leave unadjusted and differs from head to head. Remember, it's the balance between the E and F photo diodes. Compensates for mechanical misalignment and efficiency differences.
Hi Willem,
The old scope is okay for looking at the servos, but the RF or EFM pattern requires 0.5 uS / Div for horizontal and 0.5 V / Div for vertical.
I do agree that it sounds like a tooth broken from the rack gear. Commonly if the owner (you) plays home burned CD's, the mech may get run to the end and break a tooth off. It gets into the grease and can not be seen easily. Remove the drive gear from between the rack and motor drive. Then see if your head moves smoothly back and forth. Clean everything off and inspect the gears, you may also have one cracked from the center out. Relubricate with white lithium grease. As little as possible!
The reason I condemned your new head is simple. One servo was oscillating and that is not right. Always remember that new does not mean good. I've had a few bad heads over the years. To be sure, use the 'scope to find the minimum low and high frequency servo noise. If the head oscillates there, it's bad.
Hi Peter,
Denon stopped using Molykote for these applications. They had some problems with it. I just do what I'm told like a good little techy!
-Chris
Thanks to all of you!
Yesterday I degreased, cleaned and regreased the mechanics, using a very light white teflon grease I use for guitar tuners (I found no broken gear teeth. I ran the motor on a 9V battery as Mooly suggested. The head appeared to move smoothly. Again I took precautions as to static electricity.
After reassembling the Denon it was unwilling to play any disk. Wen I inserted a disk the head danced, the disk was spun for a while and the laser unit made the familiar search sounds. No track numbers appeared in the display and after a while the motor stopped, so I think the zero-track was not found.
So I think I have to buy another KSS210A, or do I? Perhaps it is wiser to buy a new player, like the DCD500??
Willem
Yesterday I degreased, cleaned and regreased the mechanics, using a very light white teflon grease I use for guitar tuners (I found no broken gear teeth. I ran the motor on a 9V battery as Mooly suggested. The head appeared to move smoothly. Again I took precautions as to static electricity.
After reassembling the Denon it was unwilling to play any disk. Wen I inserted a disk the head danced, the disk was spun for a while and the laser unit made the familiar search sounds. No track numbers appeared in the display and after a while the motor stopped, so I think the zero-track was not found.
So I think I have to buy another KSS210A, or do I? Perhaps it is wiser to buy a new player, like the DCD500??
Willem
You did disconnect the motor ( unsolder at least one wire or remove the plug to the PCB ). Not forgotten to reconnect ? It doesn't really sound like a duff pickup to me.
If you move the pickup away from the disc center ( turn the motor by hand ) with the power off and then switch on does the pickup correctly position itself ?
The fact that the disc spins ( does it spin at what appears to be a normal speed -- not a million miles an hour ) suggests that the laser has focused on the disc surface. Does it spin for a while or does it just give a kick.
If you have grease on your fingers you haven't accidently touched the lens have you, that's easily done
Hi Mooly,
When I tried the player tonight it recognized the disk and played it, though squealingly, for about 20 seconds, but then it hung. Pity, I could not repeat this little succes. I inspected the lense and, allthough it did not appear greasy, I cleaned it with a cotton swab and 93% alcohol. I inspected the return of the sled after moving the motor by hand. Smoothly!
I found a German firm, selling ten (!) of these laserunits for € 29, about 22 pounds. Don't you think I should buy a carton and try a new laserunit as Chris suggests?
Thank you for your kind advise.
Willem
When I tried the player tonight it recognized the disk and played it, though squealingly, for about 20 seconds, but then it hung. Pity, I could not repeat this little succes. I inspected the lense and, allthough it did not appear greasy, I cleaned it with a cotton swab and 93% alcohol. I inspected the return of the sled after moving the motor by hand. Smoothly!
I found a German firm, selling ten (!) of these laserunits for € 29, about 22 pounds. Don't you think I should buy a carton and try a new laserunit as Chris suggests?
Thank you for your kind advise.
Willem
There is nothing lost I suppose.
Make sure they are 210 A's. These pickups were fitted in huge numbers in audio systems of all makes and the price of a genuine Sony part was around £45 a few years ago. Then they started appearing as "unbranded" parts at very low price -- but they were OK, we fitted literally 100's, it was easier and cheaper to replace a suspect one than risk the job bouncing.
Take it slowly, and did you move any other pot's ? Did you mark them all like I suggested so they could be put back ?
As ever, a check with a 'scope would take a lot of the guesswork out of all this.
Make sure they are 210 A's. These pickups were fitted in huge numbers in audio systems of all makes and the price of a genuine Sony part was around £45 a few years ago. Then they started appearing as "unbranded" parts at very low price -- but they were OK, we fitted literally 100's, it was easier and cheaper to replace a suspect one than risk the job bouncing.
Take it slowly, and did you move any other pot's ? Did you mark them all like I suggested so they could be put back ?
As ever, a check with a 'scope would take a lot of the guesswork out of all this.
Hi rabbitz,
No problem. I still have a container with the Denon Molykote I had to buy. Little used due to the command to not use the stuff. I have other assorted goo from Denon and other manufacturers I use. One of the best things I found was a thick silicone lubricant. It works wonders with pressure clamps as it damps out a lot of vibration.
Hi Willem,
There is a shorting pad on these heads. Just so you know. You should have had to remove the short on your new head before it would work. If you didn't, the head was used.
Hi Mooly,
I would want to make sure I had a Sony part here. There are Chinese factories making just about everything. If the quality is good, then great. I'm still unsure about these parts. I'd say that 22 Euro is too cheap for 10 heads, just to agree with you on this.
-Chris
No problem. I still have a container with the Denon Molykote I had to buy. Little used due to the command to not use the stuff. I have other assorted goo from Denon and other manufacturers I use. One of the best things I found was a thick silicone lubricant. It works wonders with pressure clamps as it damps out a lot of vibration.
Hi Willem,
There is a shorting pad on these heads. Just so you know. You should have had to remove the short on your new head before it would work. If you didn't, the head was used.
Hi Mooly,
I would want to make sure I had a Sony part here. There are Chinese factories making just about everything. If the quality is good, then great. I'm still unsure about these parts. I'd say that 22 Euro is too cheap for 10 heads, just to agree with you on this.
-Chris
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