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Troubleshooting CD Players

I have a Magnavox FD1000SL cd player that I bought at an estate sale. It powered up and played but some buttons didn’t work. Not sure which ones now. It played for a while but quit after awhile. The lights would all light and it would try to spin but just wouldn’t. I opened it up and checked the motor. It was fine, I then checked the voltage to the motor and there was essentially none. I decided to recap it. I recapped (electrolytics only) it. While in there I also checked all the diodes and all were good. After the recap I put the covers back on, powered up on DBT and it was good. I hooked it up to my receiver and powered up on main power and all lamps lit. Put in a cd and hit play. It played flawlessly and all functions worked. I played it for a couple of hours and shut it off. Now when I put the covers back on I didn’t screw them down. I think I made a mistake ( not being familiar with the machine…stupid me) and screwed the transport screws down. After putting in all the screws I played it again. It worked fine for almost a minute then started to screech and lost sound. Now here are here what I have.

Unit powers up and all lights are on
Disc spins really fast
No sound
Play button works
Next button doesn’t work
Stop button works
Pause button doesn’t work (I assume)
CM I assume doesn’t work
Select button doesn’t work
Cancel button doesn’t work
Store button doesn’t work
Repeat button works
Rewind and FWD buttons don’t work

Any help is appreciated
 
Dear all,

I hope this is the appropriate place to ask my question. For sentimental reasons, I recently bought a used Sony CDP-M79 player for my music studio. While it initially seemed to play fine during a short test, I discovered an issue (or perhaps 2) when I tried playing full-length CD's:

1) It occasionally skips, and skips only forward in time.
2) Also, it skips very easly upon vibrations (when I walk around, gently bump into the furnature it sits in). Not sure if both issues share the same root cause, or have multiple causes.

Attempt #1: Being fairly experienced with electronic repairs of electronic musical instruments (but not on CD players!) I opened it up. My first step was to clean the laser lense, which I did with some isopropyl alcohol and a Q-tip. After that I tested and a full CD now played without any skipping. Great! Closed the lid, and installed it in the studio. After a couple of days, I played another CD and the skipping was back....

Attempt #2: After this, my next step was to take a look at a possible need for lubrication. I learned online that the grease on the laser sled gears and oil on the rails can dry out over the years, and visually it indeed looked that way. So I cleaned the rails and gears from the old stuff as much as I could. Then I wondered what to apply, read discussions online about white lithium grease versus silicone grease, and decided to buy and apply some Griffon silicon grease to the gears, which was available in a nearby store. For the rails I used a silicone based oil. After testing, this seemed to have made the issue of skipping much worse! I thought I had perhaps applied to much, or that the grease may have been too thick in viscosity for this application, so I removed most of it, leaving only a little in place. This seemed to help somewhat, but definitely not enough.

Attempt #3: Next I took a closer look at the symptom: skipping forward! I played a CD while observing the laser sled movements, and discovered that even without audible skipping, it seems to regularly overshoot its optimal position. Sometimes it makes nice, small adjustments in forward direction, and sometimes a bigger one, followed by small movements backwards. I couldn't confirm weather this is also happening what skipping is audible, but I found it suspicious and started reading about sled motor issues. On this forum I read about how to measure sled motor voltage, and decided to do so. The PCB connector clearly labels the pin supplying voltage to the sled motor, so I hooked up my oscilloscope, checked it's voltage accuracy against a known reference, and then started measuring the sled motor voltage during CD playing. What I observed is that on the moments of overshooting, the voltage rises up to 1V, before the sled motor comes into action. Shortly after, the voltage becomes negative, partially reversing the motor to compensate for the overshoot. Smaller movements without clear signs of overshoot show much lower voltages. For reference: the sled motor is a Mabuchi RF-310T-11400. I did a quick check of the gears, to identify potential cracks, but couldn't find any.

My question is: how to proceed from here? Does the above indicate that the sled motor is worn/dirty? Or could it still be an issue with the gears or lubrication? How do I diagnose the root cause? Should I consider unmounting the sled motor and test it seperately (without load), but how will I know when it performs up to spec? And if the sled motor is the cause, is there any way to repair/clean it, or does it need replacement?

Also... do you think it will also fix the player's sensitivity to vibration? Or am I looking at two seperate issues here?

Any help is highly appreciated!

Rutger

Edit: after KingJT I made an edit to explain that on the sled rails I in fact used silicone oil instead of grease.
 
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@rutgerv I have found sewing machine oil to work much better for the rail lube.
And eyeglass cleaning solution for the lens.
If the lens is plastic the alcohol might damage it. I believe it would cause it to cloud up so if it didn’t do that hopefully no harm.
 
rutgerv said:
Dear all,

I hope this is the appropriate place to ask my question. For sentimental reasons, I recently bought a used Sony CDP-M79 player for my music studio. While it initially seemed to play fine during a short test, I discovered an issue (or perhaps 2) when I tried playing full-length CD's:

1) It occasionally skips, and skips only forward in time.
2) Also, it skips very easly upon vibrations (when I walk around, gently bump into the furnature it sits in). Not sure if both issues share the same root cause, or have multiple causes.

Attempt #1: Being fairly experienced with electronic repairs of electronic musical instruments (but not on CD players!) I opened it up. My first step was to clean the laser lense, which I did with some isopropyl alcohol and a Q-tip. After that I tested and a full CD now played without any skipping. Great! Closed the lid, and installed it in the studio. After a couple of days, I played another CD and the skipping was back....

Attempt #2: After this, my next step was to take a look at a possible need for lubrication. I learned online that the grease on the laser sled gears and rails can dry out over the years, and visually it indeed looked that way. So I cleaned the rails and gears from the old grease as much as I could. Then I wondered what to apply, read discussions online about white lithium grease versus silicone grease, and decided to buy and apply some Griffon silicon grease, which was available in a nearby store. After testing, this seemed to have made the issue of skipping much worse! I thought I had perhaps applied to much, or that the grease may have been too thick in viscosity for this application, so I removed most of it, leaving only a little in place. This seemed to help somewhat, but defintely not enough.

Attempt #3: Next I took a closer look at the symptom: skipping forward! I played a CD while observing the laser sled movements, and discovered that even without audible skipping, it seems to regularly overshoot its optimal position. Sometimes it makes nice, small adjustments in forward direction, and sometimes a bigger one, followed by small movements backwards. I couldn't confirm weather this is also happening what skipping is audible, but I found it suspicious and started reading about sled motor issues. On this forum I read about how to measure sled motor voltage, and decided to do so. The PCB connector clearly labels the pin supplying voltage to the sled motor, so I hooked up my oscilloscope, checked it's voltage accuracy against a known reference, and then started measuring the sled motor voltage during CD playing. What I observed is that on the moments of overshooting, the voltage rises up to 1V, before the sled motor comes into action. Shortly after, the voltage becomes negative, partially reversing the motor to compensate for the overshoot. Smaller movements without clear signs of overshoot show much lower voltages. For reference: the sled motor is a Mabuchi RF-310T-11400. I did a quick check of the gears, to identify potential cracks, but couldn't find any.

My question is: how to proceed from here? Does the above indicate that the sled motor is worn/dirty? Or could it still be an issue with the gears or lubrication? How do I diagnose the root cause? Should I consider unmounting the sled motor and test it seperately (without load), but how will I know when it performs up to spec? And if the sled motor is the cause, is there any way to repair/clean it, or does it need replacement?

Also... do you think it will also fix the player's sensitivity to vibration? Or am I looking at two seperate issues here?

Any help is highly appreciated!

Rutger
Click to expand...
You could carefully disassemble the motor and clean the commutator & brushes and oil the bushings.
 
Thanks for the replies!

@KingJT: in my original post I forgot to mention that I did not put silicone grease on the sled rails, but used silicone oil (much thinner) instead. Laser lense seems not to have suffered from the isopropyl, but will keep your suggestion in mind for next time cleaning.

@redk9258: I'm considering to disassemble the sled motor, but given the player's sensitivity to shock, I decided to first investigate other factors that might add to the skipping problems, before taking the effortful step of removing the sled motor.

Here's an update of my attempts to diagnose the shock sensitivity problem:
* hooked up my analog (20Mhz) scope to the RF test point to check the eye pattern (see picture attached). Scope was set to DC, with a vertical resolution of 0.5V per square. Based on my limited experience with CD players, I'd say the eye pattern looks clean, but it's peak-to-peak amplitude (approx 0.65Vpp) much lower than specified in the service manual (1.3Vpp, +/-0.3V). My interpretation of this is: the KSS150A laser in this player is getting old...

* observation: when I put the sled motor control voltage on scope, I could see a distinct voltage wiggle roughly coinciding with the CD's rotation frequency. I saw the same wiggle in the overall eye patterns (the whole patterns wobbling slightly up/down as a whole), and I could even physically observe this wiggle in the laser lense when playing. I presume it has to do with the CD tracks being slightly excentric and the laser position having to compensate for it to mainain tracking? Or does it point at something else?

Regards,

Rutger
 

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Nautiker said:
Just FYI to Dr. Audio's recommendation for Liberty Electronics, I've had good luck buying from Dalbani on eBay, in particular their Hitachi HOP-M3 lasers have been good - and readily available. If I need another, I may give Liberty a try...

Also, I have found this laser list to be another pretty good reference:
Click to expand...
A little bit of info goes a long way...

With the above links, I found the laser/DAC I need for my player and to me it's worth 30 bucks. I have a JVC XL-V333 I purchased new in 1989 (I was 18 LOL) that I am still using today. It is the most reliable piece of gear I've ever had, only needing belts for the tray and pick up in all this time. I bought another one cheap about 10 years ago to use in the garage that appears to need the DAC now. Think I'll give give it a shot, worst case I'll have experience in a new repair procedure.
 
rutgerv said:
* hooked up my analog (20Mhz) scope to the RF test point to check the eye pattern (see picture attached). Scope was set to DC, with a vertical resolution of 0.5V per square. Based on my limited experience with CD players, I'd say the eye pattern looks clean, but it's peak-to-peak amplitude (approx 0.65Vpp) much lower than specified in the service manual (1.3Vpp, +/-0.3V). My interpretation of this is: the KSS150A laser in this player is getting old...
Click to expand...
Is this with a real pressed CD or CD-R? CD-R will have a lower output. Try several pressed CDs.
 
If in need the Mabuchi RF-310T-11400 spindle motor can be found on ebay, they are cheap. They are used a lot by RC model builders.
I replace them rather than try to repair them. Usually the upper bushing gets worn and the spindle wobbles.

For reference they have a 22mm long spindle. When looking at ebay offers be careful to avoid the used ones, they are often sold used but not well stated that they are used.

Cheers,
James
 
@dr*audio Do you have any experience with a Mitsubishi DP-109? I have one that just reads ":" on the display, tray opens, the mechanism pushes the disc into position, but it doesn't spin at all. The laser mechanism is covered, so I can't see if it's engaging, but the whole piece looks a bit different than what I'm used to seeing, so I'm not sure of where the best place to start.
 
cma2032 said:
@dr*audio Do you have any experience with a Mitsubishi DP-109? I have one that just reads ":" on the display, tray opens, the mechanism pushes the disc into position, but it doesn't spin at all. The laser mechanism is covered, so I can't see if it's engaging, but the whole piece looks a bit different than what I'm used to seeing, so I'm not sure of where the best place to start.
Click to expand...
Look at the focus out with a scope. If you don't see a rising and falling waveform, it isn't doing Focus Search, which means it hasn't loaded the disc completely. If you see focus search and the CD doesn't spin, the pickup is shot.
 
Hi all,

a Rotel RCD-06 is driving me crazy with an intermittent strange fault.
sometimes it plays perfectly ok for 30mn, sometime after few minutes or seconds it shut's hitself totaly off or "freeze" (LCD stays on but no more sound no more move)
i looked for a power supply problem but still not catched this intermittent problem.
i'mstuck and begging for help please
 
phil916 said:
Hi all,

a Rotel RCD-06 is driving me crazy with an intermittent strange fault.
sometimes it plays perfectly ok for 30mn, sometime after few minutes or seconds it shut's hitself totaly off or "freeze" (LCD stays on but no more sound no more move)
i looked for a power supply problem but still not catched this intermittent problem.
i'mstuck and begging for help please
Click to expand...
Check the 5V supply with a scope. Look for ripple.
 
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i checked better there is 3x IS3050J (2 with heatsink 1 without)
and 2 x 15V -15V regulators

7915 input -23.2V output -14,91V (output seems tired...)
7815 input 22V output 15,05V
IS3050J:
U901 input 9,45V* output 4,995V
U931 input 9,42V* output 5,010V
U961 input 15,04V output 4,986V

*if ROTEL RCD-02 schematic applies should have 10,3Vdc from rectified filtered main transformer...and this is without CD turning once CD is turning voltage goes down to 8,3Vdc though outputs stay ok near 5V.schema rotel CDR-02.PNG


here is problem catched on video

Download

A file is available for download and streaming via UploadNow by following this link
uploadnow.io uploadnow.io
 
Also see if you can identify the reset line and look at it with a scope. Other things:
Look at the output of the IR receiver with a scope.
Tighten all screws on the pcb. They may be used to complete ground paths.
 
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