Since so many of these inexpensive players seem to have a high rate of failure, I thought it would be a good idea to have a thread dedicated to their repair.
I'll start with the player I'm currently repairing
. I bought a DCM-370 from a seller who openly disclosed that the player needed repair. When it arrived, it would play bits and pieces of audio throughout a disc, with a lot of long-distance skipping. After attempting to clean the lens, lubricate the gears, etc., etc., the problem didn't improve. Actually, the more I used it, the less it played until it eventually couldn't even read the TOC.
Knowing that most instances of these problems were solved either by replacing the laser or the sled / spindle motors, I elected to purchase a whole new assembly (pickup, mechanism, everything). When I put it in the player and tried it out, it wouldn't spin the CD. I figured the spindle motor on the new assembly was dead. To confirm it, I took the new laser and put it on the old assembly. Still no spin. I thought this was odd, so I put the old laser on the new assembly, and lo and behold, the disc spun! However, it made the same clicking noises it had when it was on the old assembly and failed to read the TOC.
Any suggestions?
I'll start with the player I'm currently repairing
. I bought a DCM-370 from a seller who openly disclosed that the player needed repair. When it arrived, it would play bits and pieces of audio throughout a disc, with a lot of long-distance skipping. After attempting to clean the lens, lubricate the gears, etc., etc., the problem didn't improve. Actually, the more I used it, the less it played until it eventually couldn't even read the TOC.Knowing that most instances of these problems were solved either by replacing the laser or the sled / spindle motors, I elected to purchase a whole new assembly (pickup, mechanism, everything). When I put it in the player and tried it out, it wouldn't spin the CD. I figured the spindle motor on the new assembly was dead. To confirm it, I took the new laser and put it on the old assembly. Still no spin. I thought this was odd, so I put the old laser on the new assembly, and lo and behold, the disc spun! However, it made the same clicking noises it had when it was on the old assembly and failed to read the TOC.
Any suggestions?
Now With Pictures! (56k death)
Larger images available upon request.
Here are a few pictures which show some of the stages of disassembly of the DCM-370:
Cover removed, circuit board on
Cover removed, circuit board off, flex cables removed
Circuit board close-up, note DACs
Back of carousel, full view inc. optical pickup
Back of carousel, optical pickup close-up
Back of carousel, optical pickup removed, flex cables removed
Optical pickup / mechanism by itself
Larger images available upon request.
Here are a few pictures which show some of the stages of disassembly of the DCM-370:
Cover removed, circuit board on
An externally hosted image should be here but it was not working when we last tested it.
Cover removed, circuit board off, flex cables removed
An externally hosted image should be here but it was not working when we last tested it.
Circuit board close-up, note DACs
An externally hosted image should be here but it was not working when we last tested it.
Back of carousel, full view inc. optical pickup
An externally hosted image should be here but it was not working when we last tested it.
Back of carousel, optical pickup close-up
An externally hosted image should be here but it was not working when we last tested it.
Back of carousel, optical pickup removed, flex cables removed
An externally hosted image should be here but it was not working when we last tested it.
Optical pickup / mechanism by itself
An externally hosted image should be here but it was not working when we last tested it.
Hi infinitesymph,
Isn't that a standard Sony Mechanism? The head looks like a KSS-240A or variant.
The only high rates of failure I've seen is when people use the Random (read DIE) button. That tends to tear up the spindle motor. If it's "knocking" the bearing in the spindle motor may be shot. Look at the gear track on the side of the head for bits of nylon that may come from the gear (small section). Also check that the CD isn't hitting the edge of the tray.
If you have a 'scope, watch the eye pattern.
-Chris
Isn't that a standard Sony Mechanism? The head looks like a KSS-240A or variant.
The only high rates of failure I've seen is when people use the Random (read DIE) button. That tends to tear up the spindle motor. If it's "knocking" the bearing in the spindle motor may be shot. Look at the gear track on the side of the head for bits of nylon that may come from the gear (small section). Also check that the CD isn't hitting the edge of the tray.
If you have a 'scope, watch the eye pattern.
-Chris
Laser Woes
anatech: Thanks for the reply!
You're right, it's a Sony KSS-213C laser which is quite common and has many cheap replacements. I opted to replace the whole mechanism (KSM-213CCM) instead of troubleshooting the Mabuchi motors individually.
The spindle motor dying was my initial thought, since I'd heard technicians say that the rate of laser failure is lower than what most people think. However, even with the replacement assembly, neither laser was able to read the TOC.
I tried all variations of lasers and assemblies:
1. new laser + new assembly = no spin
2. new laser + old assembly = no spin
3. old laser + new assembly = spin, but no read
4. old laser + old assembly = spin, but no read
So, in both cases, the spindle motor didn't spin the CD when the new laser was in place. Perhaps the new laser is DOA? To be safe, I'm shipping it back for a replacement.
Are there any tracking/focus adjustments on these lasers? I know there's a laser power adjustment near the entry point for the flex cable, but power doesn't seem to be the issue (and I've tried adjusting it with no noticeable results).
Another question: In the picture of the circuit board, near the bottom are what appear to be two adjustable potentiometers. The circular near the flex cable reads "PIO1" and the other looks like "TIO1." Any idea what these might adjust?
anatech: Thanks for the reply!
You're right, it's a Sony KSS-213C laser which is quite common and has many cheap replacements. I opted to replace the whole mechanism (KSM-213CCM) instead of troubleshooting the Mabuchi motors individually.
The spindle motor dying was my initial thought, since I'd heard technicians say that the rate of laser failure is lower than what most people think. However, even with the replacement assembly, neither laser was able to read the TOC.
I tried all variations of lasers and assemblies:
1. new laser + new assembly = no spin
2. new laser + old assembly = no spin
3. old laser + new assembly = spin, but no read
4. old laser + old assembly = spin, but no read
So, in both cases, the spindle motor didn't spin the CD when the new laser was in place. Perhaps the new laser is DOA? To be safe, I'm shipping it back for a replacement.
Are there any tracking/focus adjustments on these lasers? I know there's a laser power adjustment near the entry point for the flex cable, but power doesn't seem to be the issue (and I've tried adjusting it with no noticeable results).
Another question: In the picture of the circuit board, near the bottom are what appear to be two adjustable potentiometers. The circular near the flex cable reads "PIO1" and the other looks like "TIO1." Any idea what these might adjust?
Movie - DCM-370 Skipping
I recorded a brief movie of the problem in action a few days ago.
Link, video portion requires DivX codec
The background noise is an old computer humming, but one can clearly see and hear the pickup trying to track. Sorry about the poor lighting; my flashlight was almost dead. Maybe this will give a better idea of what the cause might be.
-Jameson
I recorded a brief movie of the problem in action a few days ago.
Link, video portion requires DivX codec
The background noise is an old computer humming, but one can clearly see and hear the pickup trying to track. Sorry about the poor lighting; my flashlight was almost dead. Maybe this will give a better idea of what the cause might be.
-Jameson
Hi Jameson,
That looks like the E-F balance is off. Touchy adjustment. The lighting was terrible!
Get the manual from Denon. They are not expensive. Do not touch the pots on the laser head. I do sometimes, but I have a lot of experience doing this. It is very easy to make things worse. I may touch up the E-F balance from time to time. Never the power.
Buy a new flex cable (white flat thing). It should not cost much.
Check the turntable height on the mech when you get it. They tend to slide downwards if they go anywhere. Your old mechanism is more suspect that the new one.
You really need an oscilloscope and test discs to troubleshoot properly, but Denon builds in a test program (Thank you Denon!!). You may get some clues trying this. It is intended to be used with a standard disc. CA1094 or similar if I recall correctly. Servicing CD players is normally enjoyable for me. I love squeezing that last bit of performance out of them.
-Chris
That looks like the E-F balance is off. Touchy adjustment. The lighting was terrible!
Get the manual from Denon. They are not expensive. Do not touch the pots on the laser head. I do sometimes, but I have a lot of experience doing this. It is very easy to make things worse. I may touch up the E-F balance from time to time. Never the power.
Buy a new flex cable (white flat thing). It should not cost much.
Check the turntable height on the mech when you get it. They tend to slide downwards if they go anywhere. Your old mechanism is more suspect that the new one.
You really need an oscilloscope and test discs to troubleshoot properly, but Denon builds in a test program (Thank you Denon!!). You may get some clues trying this. It is intended to be used with a standard disc. CA1094 or similar if I recall correctly. Servicing CD players is normally enjoyable for me. I love squeezing that last bit of performance out of them.
-Chris
D'oh
E-F balance, eh? That's bad news, considering this was meant to be a budget purchase .
The service manual seems to be about $25 from Denon, with $10 for the flex cable. Even then, I don't have an oscilloscope or test CDs. Keep in mind my initial investment in this player was $15! So far I'm at $50 (player + soldering equipment + new laser assembly), which isn't bad, but it's also true that a used DCM-370 in working condition goes for about $60-$70. I guess it might develop these same problems over time, though.
If I promise not to blame you when I screw up the CD player, will you tell me where the E-F balance adjustment is located?
I'd consider sending it in for service if it was a more robust or expensive player, but if I can't fix it myself, it probably won't get fixed.
-Jameson
E-F balance, eh? That's bad news, considering this was meant to be a budget purchase
.The service manual seems to be about $25 from Denon, with $10 for the flex cable. Even then, I don't have an oscilloscope or test CDs. Keep in mind my initial investment in this player was $15! So far I'm at $50 (player + soldering equipment + new laser assembly), which isn't bad, but it's also true that a used DCM-370 in working condition goes for about $60-$70. I guess it might develop these same problems over time, though.
If I promise not to blame you when I screw up the CD player, will you tell me where the E-F balance adjustment is located?
I'd consider sending it in for service if it was a more robust or expensive player, but if I can't fix it myself, it probably won't get fixed.
-Jameson
Hi Jameson,
Deep breath now.
The E-F Balance is on the head (on a 240 anyway). So it's either a defective head or it could possibly be the flex cable.
I do not have the manual for your machine or I'd instruct you more exactly. But you do need a 'scope and test disc to perform the adjustment. You need the manual to start the test mode (can't remember on this one) and step through the program.
The value of the machine is relative. It has a good mechanism for one, the were fairly problem free (up here) for two. That's your call. I'd be fixing it without thinking about it too much if it were mine. You do not have the troubleshooting skills or equipment to narrow down the problem without buying a little extra.
-Chris
Deep breath now.
The E-F Balance is on the head (on a 240 anyway). So it's either a defective head or it could possibly be the flex cable.
I do not have the manual for your machine or I'd instruct you more exactly. But you do need a 'scope and test disc to perform the adjustment. You need the manual to start the test mode (can't remember on this one) and step through the program.
The value of the machine is relative. It has a good mechanism for one, the were fairly problem free (up here) for two. That's your call. I'd be fixing it without thinking about it too much if it were mine. You do not have the troubleshooting skills or equipment to narrow down the problem without buying a little extra.
-Chris
KSS-213C and KSS-240A
I see you're a big advocate of replacing the flex cable from the pickup to the circuit board, so I went ahead and ordered the appropriate replacement (Denon part #: 9580024400). I'll wait to try anything new until the flex cable and the replacement assembly arrive.
Until then, I thought I'd ask about what the single potentiometer on the KSS-213C might be for, since the KSS-240A appears to have three.
Here are some pictures for comparison:
KSS-240A
KSS-213C
Is the single pot a simplified adjustment?
-Jameson
I see you're a big advocate of replacing the flex cable from the pickup to the circuit board, so I went ahead and ordered the appropriate replacement (Denon part #: 9580024400). I'll wait to try anything new until the flex cable and the replacement assembly arrive.
Until then, I thought I'd ask about what the single potentiometer on the KSS-213C might be for, since the KSS-240A appears to have three.
Here are some pictures for comparison:
KSS-240A
An externally hosted image should be here but it was not working when we last tested it.
KSS-213C
An externally hosted image should be here but it was not working when we last tested it.
Is the single pot a simplified adjustment?
-Jameson
Hi Jameson,
I honestly don't know what it's for. I would have to search around for that info. Could be laser power, which is historically mounted on the head. Focus offset and E-F Balance may be servo corrected in the new machines. This means there are no adjustments that you can make.
I see from the main board picture that this is the case.
-Chris
I honestly don't know what it's for. I would have to search around for that info. Could be laser power, which is historically mounted on the head. Focus offset and E-F Balance may be servo corrected in the new machines. This means there are no adjustments that you can make.
I see from the main board picture that this is the case.
-Chris
Circuit Board Pots?
Chris... Fast replies! Thanks again.
What about these pots on the circuit board? (with artistic addition)
-Jameson
Chris... Fast replies! Thanks again.
What about these pots on the circuit board? (with artistic addition
)An externally hosted image should be here but it was not working when we last tested it.
-Jameson
Did this thread die? I was reading it with curiousity as I have a DCM440 (I think that's the one) at home that has skipping issues. Namely it skips if I walk across the floor. It also has an issue that the drawer will no longer stay open. It opens, then immediately closes. I was hoping for some insight as to what to try with this to help it out! I still like it other than those two issues! (And I haven't even done anything to it yet!)
Hi Schaef,
I think Jameson is waiting for some parts.
The tray sounds like solder joints or dirty contacts on the limit switch. If it's an optocoupler, clean the dust out and look at the soldering on the board.
The skipping thing could be that it's in a bad location (floor is springy). You may also have a laser that is getting weak. Only tests on the bench will tell for sure.
-Chris
I think Jameson is waiting for some parts.
The tray sounds like solder joints or dirty contacts on the limit switch. If it's an optocoupler, clean the dust out and look at the soldering on the board.
The skipping thing could be that it's in a bad location (floor is springy). You may also have a laser that is getting weak. Only tests on the bench will tell for sure.
-Chris
anatech said:
Actually, its funny, I think the drawer thing is that the unit may be getting slightly twisted or something, because when I took it down to my bench to look at, it worked perfectly. At least once I opened the case, it wouldn't do it. Put it back together, put it back in the stereo rack, and it started up again. My current thought on solution is to eventually replace the stereo rack.
I'm figuring a weak laser, as even though the floor is slightly springy, its not THAT springy. What are the steps involved with testing the laser? I have a VMM, a scope, and access to engineers who would be willing to offer advice as well. I believe I need a test CD (where do I get one of these?) and the repair manual to do this, correct? Some pointers and suggestions would be most welcome!
Hi Schaef,
The manual is not expensive from Denon, just order it and follow the instructions. The test CD old number was CA-1094, they will have a sub. It's just a music CD that they test to make sure the parameters are in the ballpark. I always just used the test disc and didn't worry about it.
Your scope needs to be able to sweep at 0.5uS / Div to see the eye pattern properly. Vertical should be around 0.5V/Div, corrected for a X10 probe (50 mV / Div for a scope that does not adjust for a X10 probe automatically). Look for the RF (or EF) test point.
Check the case screws in case they are too long or in the wrong position. Hair and other debris can cause trouble as well.
-Chris
The manual is not expensive from Denon, just order it and follow the instructions. The test CD old number was CA-1094, they will have a sub. It's just a music CD that they test to make sure the parameters are in the ballpark. I always just used the test disc and didn't worry about it.
Your scope needs to be able to sweep at 0.5uS / Div to see the eye pattern properly. Vertical should be around 0.5V/Div, corrected for a X10 probe (50 mV / Div for a scope that does not adjust for a X10 probe automatically). Look for the RF (or EF) test point.
Check the case screws in case they are too long or in the wrong position. Hair and other debris can cause trouble as well.
-Chris
Desoldering ESD Protection Point
Welcome to the discussion, Schaef!
Guys,
A few days after I returned the optical mechanism, I received a call from the place that sold it to me. The guy asked if I'd remembered to desolder the protection point that joins two pins to prevent damage from static discharge during shipping.
Whoops! I hadn't, though I did look for the point since I'd read about other people replacing the laser. The (now possibly unnecessary) replacement arrived this afternoon and, after taking another look at it, I still can't find the ESD protection point.
Where is it normally located?
-Jameson
Welcome to the discussion, Schaef!
Guys,
A few days after I returned the optical mechanism, I received a call from the place that sold it to me. The guy asked if I'd remembered to desolder the protection point that joins two pins to prevent damage from static discharge during shipping.
Whoops! I hadn't, though I did look for the point since I'd read about other people replacing the laser. The (now possibly unnecessary) replacement arrived this afternoon and, after taking another look at it, I still can't find the ESD protection point.
Where is it normally located?
-Jameson
Schaef's Drawer Problem
Schaef,
A suggestion about your drawer problem... Since I've had the DCM-370 open for such a long time, I've encountered a few problems along the way that were purely the result of a deseated connector.
On my model, these two connectors on the right side are what connect to the drawer controls on the front panel.
A few odd things happened when I didn't plug them all the way in (especially with the frontmost connector):
1. The drawer closed as soon as it reached the open position.
2. The carousel wouldn't stop spinning.
3. The carousel made a jerky motion like it wanted to move but couldn't.
It couldn't hurt to try unplugging and replugging those, especially since it won't require removal of anything else to get to them.
-Jameson
Schaef,
A suggestion about your drawer problem... Since I've had the DCM-370 open for such a long time, I've encountered a few problems along the way that were purely the result of a deseated connector.
On my model, these two connectors on the right side are what connect to the drawer controls on the front panel.
An externally hosted image should be here but it was not working when we last tested it.
A few odd things happened when I didn't plug them all the way in (especially with the frontmost connector):
1. The drawer closed as soon as it reached the open position.
2. The carousel wouldn't stop spinning.
3. The carousel made a jerky motion like it wanted to move but couldn't.
It couldn't hurt to try unplugging and replugging those, especially since it won't require removal of anything else to get to them.
-Jameson
KSS-213C Head
Chris,
Here are pictures of the pickup itself...
Side with cable insert
Opposite side
I didn't notice until I took the picture, but that blob all the way on the left looks the most suspicious as there are no pins going through it. Is that the point to desolder?
-Jameson
Chris,
Here are pictures of the pickup itself...
Side with cable insert
An externally hosted image should be here but it was not working when we last tested it.
Opposite side
An externally hosted image should be here but it was not working when we last tested it.
I didn't notice until I took the picture, but that blob all the way on the left looks the most suspicious as there are no pins going through it. Is that the point to desolder?
-Jameson