Hoping that I might get some help with my Luxman DZ-112 CD player which has trouble reading discs. When I first got it, I didn't think it sounded that special, but some op amp and capacitor upgrades in the audio section turned it into my favorite sounding CD player. Those PCM1701s DACs sound pretty nice, and I think that the Luxman's +/-12V analog rails contribute to a more open sound than my two Sonys, which both use 5V rails. Consequently, I'd like to get it working reliably.
I'm not sure if there is an electrical or mechanical problem, or if it just needs proper adjustment of the trimpots. The player was prone to skipping with a light tap when I got it. I've set the VCO and Focus Bias according to the service manual (so at least two of the trimpots should be set correctly), but have found no combination of trimpot settings that will make the player read discs reliably.
Chirpy DZ-112: https://youtu.be/h4uvFJ1E-cY
When playing a CD, it starts "chirping" away endlessly, without reading the TOC (as shown in the video). By sweeping the Tracking Error trimpot, I can usually "trick" it into reading the TOC and playing the disc. Once playing, it will usually keep going, even with CD-Rs. I can find a null "sweet spot" when adjusting Tracking Error which will usually allow the player to continue to read that particular CD, but the player will usually go back to endless "chirping" when a different disc is inserted. Perplexingly, there doesn't seem to be any combination of the three remaining trimpots (Tracking Error, Focus Gain, Tracking Gain) that will make it read and play a variety of CDs every time (without messing with the Tracking Error trimpot).
In the service manual, it says to adjust the Tracking Error trimpot so that there is 0V +/-10mV at TP5 (service manual says TP6, which is an error, corrected in the DZ-122 manual). However, I measure roughly 90mV at TP5, and am unable to get to 0V no matter how the other trimpots are adjusted. Not sure if this is a sign of a component failure or??? This player was made in 1989, so it is possible that some of the electrolytics might have failed, though I see no obvious signs. I replaced four of the 22µF caps in the servo section, but observed no change. Not sure where else to look.
Wondering if any of you have an idea what might be going on and what I might try next for a solution? Hoping that this "chirping" phenomenon might point to an obvious component or failure point.
Thanks!
I'm not sure if there is an electrical or mechanical problem, or if it just needs proper adjustment of the trimpots. The player was prone to skipping with a light tap when I got it. I've set the VCO and Focus Bias according to the service manual (so at least two of the trimpots should be set correctly), but have found no combination of trimpot settings that will make the player read discs reliably.
Chirpy DZ-112: https://youtu.be/h4uvFJ1E-cY
When playing a CD, it starts "chirping" away endlessly, without reading the TOC (as shown in the video). By sweeping the Tracking Error trimpot, I can usually "trick" it into reading the TOC and playing the disc. Once playing, it will usually keep going, even with CD-Rs. I can find a null "sweet spot" when adjusting Tracking Error which will usually allow the player to continue to read that particular CD, but the player will usually go back to endless "chirping" when a different disc is inserted. Perplexingly, there doesn't seem to be any combination of the three remaining trimpots (Tracking Error, Focus Gain, Tracking Gain) that will make it read and play a variety of CDs every time (without messing with the Tracking Error trimpot).
In the service manual, it says to adjust the Tracking Error trimpot so that there is 0V +/-10mV at TP5 (service manual says TP6, which is an error, corrected in the DZ-122 manual). However, I measure roughly 90mV at TP5, and am unable to get to 0V no matter how the other trimpots are adjusted. Not sure if this is a sign of a component failure or??? This player was made in 1989, so it is possible that some of the electrolytics might have failed, though I see no obvious signs. I replaced four of the 22µF caps in the servo section, but observed no change. Not sure where else to look.
Wondering if any of you have an idea what might be going on and what I might try next for a solution? Hoping that this "chirping" phenomenon might point to an obvious component or failure point.
Thanks!
Take a look to RF signal with an oscilloscope, take pictures.
Don't replace capacitors withous any reason. This is a bad habit, a dubious electronic procedure that wait miracle solution without seeking the real cause of the problem. Don't touch potentiometers. If you want touch or manipule potentiometers, take note of its value for to have the possibility of turn back and restore original values.
Edit: Check focus and tracking coil drive transistors. Maybe it have dry joints or a bad transistor. This transistors, eight transistors, are next cable connectors, in the video are at the center of the image.
Don't replace capacitors withous any reason. This is a bad habit, a dubious electronic procedure that wait miracle solution without seeking the real cause of the problem. Don't touch potentiometers. If you want touch or manipule potentiometers, take note of its value for to have the possibility of turn back and restore original values.
Edit: Check focus and tracking coil drive transistors. Maybe it have dry joints or a bad transistor. This transistors, eight transistors, are next cable connectors, in the video are at the center of the image.
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Thanks!
To clarify, in case this was missed, I am able to get the DZ-112 to play discs; however, I am unable to get it to read and play discs reliably. If I adjust the trimpots for a given disc and get it playing reasonably well, it will usually have trouble reading the TOC on the next CD and chirp endlessly. So, I'm thinking that there's another variable at play.
Normally I would leave the trimpots alone, but made adjustments because the player was not reading properly. Also, the four capacitors that were replaced were from parts of the servo circuit where I thought a bad capacitor might be the cause, which can now be ruled out for those particular parts.
Had the eye pattern on a friend's scope and it appeared much the same as his NAD 5300, though the NAD may have provided a sharper pattern. Next time I have the board out, I will look underneath and see if there are any cold solder joints near the transistors.
To clarify, in case this was missed, I am able to get the DZ-112 to play discs; however, I am unable to get it to read and play discs reliably. If I adjust the trimpots for a given disc and get it playing reasonably well, it will usually have trouble reading the TOC on the next CD and chirp endlessly. So, I'm thinking that there's another variable at play.
Normally I would leave the trimpots alone, but made adjustments because the player was not reading properly. Also, the four capacitors that were replaced were from parts of the servo circuit where I thought a bad capacitor might be the cause, which can now be ruled out for those particular parts.
Had the eye pattern on a friend's scope and it appeared much the same as his NAD 5300, though the NAD may have provided a sharper pattern. Next time I have the board out, I will look underneath and see if there are any cold solder joints near the transistors.
I
I have another Luxman DZ-112, but I've never have touch its adjustments, except step 6 in service manual, DA distortion adjust.
I've seen adjust procedure, and all are clear except points 4 and 5, where it's necesary an "jig". I don't know what is a jig, but i suppose that there only must be some resistance or capacitor. Maybe if you inject signal generator without the "jig", you can perform the adjust, I don't know.
My Luxman DZ-112 is a good cd player, but is not the best bad disc reader, it skips some tracks in scratched cd.
In my Luxman DZ-112 the open-close trolley switches have had bad contacts, I've solved with lubricant oil.
Luxman is a rare case of honestity, service manual says distortion is 0,008%. In one channel I adjusted it to 0,007% and the other to 0,008%. Other cd player manual characteristics are full of lies, with fantastic characteristics, and when you measure it, all are lies.
This CD Luxman is not the case.
Curiosely, this is my only CD player who says if a cd disc have pre-emphasis or not. It is not very usual.
I have another Luxman DZ-112, but I've never have touch its adjustments, except step 6 in service manual, DA distortion adjust.
I've seen adjust procedure, and all are clear except points 4 and 5, where it's necesary an "jig". I don't know what is a jig, but i suppose that there only must be some resistance or capacitor. Maybe if you inject signal generator without the "jig", you can perform the adjust, I don't know.
My Luxman DZ-112 is a good cd player, but is not the best bad disc reader, it skips some tracks in scratched cd.
In my Luxman DZ-112 the open-close trolley switches have had bad contacts, I've solved with lubricant oil.
Luxman is a rare case of honestity, service manual says distortion is 0,008%. In one channel I adjusted it to 0,007% and the other to 0,008%. Other cd player manual characteristics are full of lies, with fantastic characteristics, and when you measure it, all are lies.
This CD Luxman is not the case.
Curiosely, this is my only CD player who says if a cd disc have pre-emphasis or not. It is not very usual.
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Had a friend over and we used his frequency counter to set the VCO for 4.3214MHz at pin 70 of the CXD1135. I tried to get precisely 4.3218MHz, but it seemed to "lock-in" at one working frequency and not allow finer adjustment; i.e. either it stayed at 4.3214MHz or went way out and wouldn't read the disc... I'm thinking this is close enough, meaning the VCO adjustment can now be ruled out.
I also had a look at all of the solder joints underneath the eight driver transistors; couldn't see anything obvious, but the solder was a tad thin on some, so I touched them all up with fresh solder then inspected them with a magnifying glass and checked for shorts (none).
After a little bit of pot adjustment (Tracking Gain, Focus Gain, and Tracking Balance adjusted by ear so that the laser read as quietly and reliably as possible) I got the player reading a CD and it worked nicely for a while. However, it failed to read when another disc was inserted and started the chirping behavior again (which is the problem I've been having since getting the player: I can adjust the pots to read one disc, but then it will fail, either when powered off/on, or if a different disc is inserted).
Then I felt the eight transistors and noticed most of them were surprisingly hot whilst the transport chirps away and tries to read the disc, and also observed that these transistors run cool if playback is stopped. Is it normal for these transistors to run hot, or is that potentially a sign of a failure somewhere?
I'm not sure how to proceed from here. The VCO is set and I maximized the Focus Bias with a scope a while ago, so these should be able to be ruled out. That leaves either a problem with Tracking Gain, Focus Gain, and/or Tracking Balance, or perhaps a hardware issue.
Any further troubleshooting ideas would be much appreciated!
Thanks!
If your player has a lot of hours on it, there could be problems of a more mechanical nature.
Like a worn spindle motor or simply a dirty laser pick up assembly.
I'm sure you cleaned the lens, but some pickups can get dirt on the laser diode itself and/or the inner side of the lens, and these are next to impossible to clean and replacement is the only real fix.
To be honest I have not worked on your model, and this is just general advice that comes from working on hundreds of high mileage CD/DVD drives at a disc duplication facility. Good luck.
Like a worn spindle motor or simply a dirty laser pick up assembly.
I'm sure you cleaned the lens, but some pickups can get dirt on the laser diode itself and/or the inner side of the lens, and these are next to impossible to clean and replacement is the only real fix.
To be honest I have not worked on your model, and this is just general advice that comes from working on hundreds of high mileage CD/DVD drives at a disc duplication facility. Good luck.