Troubleshooting CD Players

[valentair]

Just move the laser back and forth, the posts are what it slides on. Captain Obvious says you're welcome.

Thank you! Folks, can you recommend an instruction video(s) on taking apart, cleaning and maintaining laser assemblies of CD players? There are many of them on YouTube, but people like me who lack experience in the field, may not be able to tell the good ones from bad ones and eventually follow wrong advice.

 

[Champ]

Hello Dr. Audio! I have come to you for some sound advice. I have not been able to find my particular issue here, but could have missed it.
I have a Sonic Frontiers CD1 with the left channel creating a wooshing noise heard mostly through the tweeter because of the higher frequency. The noise only happens when music is playing and is volume dependent, gets louder as the volume is increased/decreased. The music is playing flawlessly, with overlaying sound rushing or whooshing, only way I can describe it. Several months ago I did a clean and lube of the infamous Philips CDM12.4 tray/pickup as the grease was dried up. Has been working flawlessly since and this issue just happened out of nowhere. If you could please impart some of your wisdom here it would be much appreciated.

 

[dr*audio]

Hello Dr. Audio! I have come to you for some sound advice. I have not been able to find my particular issue here, but could have missed it.
I have a Sonic Frontiers CD1 with the left channel creating a wooshing noise heard mostly through the tweeter because of the higher frequency. The noise only happens when music is playing and is volume dependent, gets louder as the volume is increased/decreased. The music is playing flawlessly, with overlaying sound rushing or whooshing, only way I can describe it. Several months ago I did a clean and lube of the infamous Philips CDM12.4 tray/pickup as the grease was dried up. Has been working flawlessly since and this issue just happened out of nowhere. If you could please impart some of your wisdom here it would be much appreciated.

The sound you are describing sounds like bit errors, but if that were the case you'd have it on both channels. Since it's only one channel I would suspect the D-A converter for that channel.

 

[Champ]

The sound you are describing sounds like bit errors, but if that were the case you'd have it on both channels. Since it's only one channel I would suspect the D-A converter for that channel.

Thanks so much for your input!
That sound expensive and not a DIY fix. It's interesting to note that this player is HDCD. I almost never play HDCD's since I own about 5, but this issue started when I inserted a HDCD disk and played it. Could that have triggered something? I see there is a complete seperate HDCD chip in this player.

 

[dr*audio]

Thanks so much for your input!
That sound expensive and not a DIY fix. It's interesting to note that this player is HDCD. I almost never play HDCD's since I own about 5, but this issue started when I inserted a HDCD disk and played it. Could that have triggered something? I see there is a complete seperate HDCD chip in this player.

I think that is a coincidence.

 

[Pio1980]

I think that is a coincidence.

How's the switch-over done?

 

[Champ]

I think that is a coincidence.

Think so too.
One other thing, the issue is intermittent. Not on every track. I just fired it up and had the issue for several tracks and has now gone. If I shut down and come back in the morning it will be back.
If I did have to replace the DAC it's an UltraAnalogue D20400A chip. Going to be tough to replace.

 

[Champ]

How's the switch-over done?

Automatic.

 

[Pio1980]

Automatic.

Could the problem be there then?

 

[redk9258]

Could you try an external D/A converter?

 

[Champ]

Could the problem be there then?

Like the good Doctor indicated, it's probably a coincidence the failure happened when it did, but hey, I suppose it is possible. Problem with this whole player is that parts are getting very hard to get. It's also a big job to get to the underside of the board to do any repairs. One large board for all components. Above my pay grade It's too bad because this is a beautiful sounding player. The UltraAnalogue D20400A is magic and not available today either.

 

[Champ]

Could you try an external D/A converter?

Unfortunately there is no input on her.

 

[dogwan]

I post back on post #789 about my Nak CD-4.

Well, I finally got a new laser from Liberty and installed it. Followed grounding protocol as best I could. I.e., wrist strap to chassis, chassis grounded to house mains. Worked on a non-conductive mat. Grounded desoldering gun to remove solder blob on laser (after installed and plugged into unit).

Results are about the same as I posted in original post.
Getting a good strong laser light as viewed through cell phone lens.
Laser jumps once when drawer closed without CD.
Without CD the spindle motor will spin around 1-1.5 rotations before stopping.
With CD it will spin approx. 1/4 turn.

I didn't take voltage measurements this time at the motor.

I'm back to thinking it might be the spindle motor going bad?
Or, maybe the drive circuitry for the motor? Maybe a bad voltage regulator?

Here's the writing on the spindle motor...
16AUG9281
MDN-4RA3FTAS

I think I remember reading a while ago that these Matsushita motors were kinda flaky.

Looking for any ideas. Don't know why I am so invested in getting this old NAK running, but I am.

I know @JASnyder will be interested as he has the same machine with the same symptoms.

Here's some pics.

Laser out




New and old laser (new in front)


New laser installed




Laser through cell phone


Spindle motor

 

[dr*audio]

Think so too.
One other thing, the issue is intermittent. Not on every track. I just fired it up and had the issue for several tracks and has now gone. If I shut down and come back in the morning it will be back.
If I did have to replace the DAC it's an UltraAnalogue D20400A chip. Going to be tough to replace.

I just thought of another thing it could be, since you mentioned it's intermittent. See if it has a muting relay. If so, I bet it's dirty.

 

[dr*audio]

MDN-4RA3FTAS is a Matsushita motor and those are crap. You can replace it with a Mabuchi disc motor if you can find one.
You might have better luck replacing the entire mechanism, as it's a Sony part; KSM-210. I have seen some Sony mechs from different vendors. I think Liberty has them, too. They come with 2 motors and the laser so you get another laser, and they are usually around $25, so a bargain.
This one has the wrong laser on it, but if the plate is the same you could use it, or just remove the motors.
https://www.allelectronics.com/item/la-10/cd-laser-optics-and-mechanism-sony-ksm/kss213/1.html
I have heard that the China sourced Mabuchi motors are junk, so be wary of them.

I post back on post #789 about my Nak CD-4.

Well, I finally got a new laser from Liberty and installed it. Followed grounding protocol as best I could. I.e., wrist strap to chassis, chassis grounded to house mains. Worked on a non-conductive mat. Grounded desoldering gun to remove solder blob on laser (after installed and plugged into unit).

Results are about the same as I posted in original post.
Getting a good strong laser light as viewed through cell phone lens.
Laser jumps once when drawer closed without CD.
Without CD the spindle motor will spin around 1-1.5 rotations before stopping.
With CD it will spin approx. 1/4 turn.

I didn't take voltage measurements this time at the motor.

I'm back to thinking it might be the spindle motor going bad?
Or, maybe the drive circuitry for the motor? Maybe a bad voltage regulator?

Here's the writing on the spindle motor...
16AUG9281
MDN-4RA3FTAS

I think I remember reading a while ago that these Matsushita motors were kinda flaky.

Looking for any ideas. Don't know why I am so invested in getting this old NAK running, but I am.

I know @JASnyder will be interested as he has the same machine with the same symptoms.

Here's some pics.

Laser out
View attachment 2794343

View attachment 2794344

New and old laser (new in front)
View attachment 2794345

New laser installed
View attachment 2794346

View attachment 2794347

Laser through cell phone
View attachment 2794348

Spindle motor
View attachment 2794349

 

[Champ]

I just thought of another thing it could be, since you mentioned it's intermittent. See if it has a muting relay. If so, I bet it's dirty.

There are 3 relays on the board. Two of them are clearly for left and right channel as indicated on in the photo. One is also on the the board near the DAC. They are
Zettler AZ830-2C-24DSE. Of coarse, discontinued. Think I have found a replacement for them.

 

[cpt_paranoia]

Oh. It's got valves in it. I would be looking at valve seating, too. Pull them out, check for oxide on the pins, plug them back in. That alone may be enough to re-establish good connection.

 

[Champ]

Oh. It's got valves in it. I would be looking at valve seating, too. Pull them out, check for oxide on the pins, plug them back in. That alone may be enough to re-establish good connection.

First thing I did was to swap the tubes. Problem said in the left channel. I did, however, give the tube pins and socket a good clean, also RCA outs.

 

[cpt_paranoia]

Looking at the right hand green, 1u 250V film capacitor, I see what looks like soldering iron burn (bottom edge & bottom RH corner). Has someone already been in there?

 

[dr*audio]

There are 3 relays on the board. Two of them are clearly for left and right channel as indicated on in the photo. One is also on the the board near the DAC. They are
Zettler AZ830-2C-24DSE. Of coarse, discontinued. Think I have found a replacement for them. View attachment 2795440View attachment 2795441

Yeah, those little crappy relays get noisy all the time. You can clean them with a piece of paper soaked in Deoxit, running it through the contacts.