SONY CDP-7F Disc read issue

[Alfmonster]

Hi Everyone, Recently picked up a Sony CDP-7F cd player that I was told worked perfectly for 6 months but then suddenly just stopped reading the cd. I read through the very helpful Laserology post on AK as well the amazing megathread for Troubleshooting CD Players by @dr*audio . There was a thread on the boomboxery forum which had nearly identical problems to my own but the fixes that were talked about didn't seem to fix my issue.

The issue with the player is that when I put a cd into the top tray and close the lid, the cd spins for about 20 seconds but fails to read the TOC. I read through the above forums and did the trouble shooting tips to conclude that the laser is working and the a lens is focusing and bringing the laser back to it's home position.

The things I’ve done so far:

Started by cleaning the lens with 99% Iso alcohol. I saw the leaf switch and followed @dr*audio recommendation and cleaned the leaf switch with deoxit applied to a piece of cardstock (didn’t have any 600grit sandpaper) like I recently did a speaker switch and saw some gunk clean off.

I also cleaned and lubricated the plastic gears lightly with lithium grease and also lubricated the sled rails with a few drops of Super Lube. (Not sure if I need more lithium grease on the gears or exactly how much Super Lube to put on the sled rails so please feel free to let me know if I should add more.)

Although I did not completely take the switch apart, I followed the boomboxery forum thread on this cd player and cleaned the lid switch by working in a few drops of deoxit D5 into the lid switch and worked it in by moving the switch a bunch.

There is no video or picture of the laser turning on during the focusing procedure however when both lid switches were pressed, the laser light did turned on.

I unfortunately do not own a scope but any help with this would be greatly appreciated. Thank you.

This is a video of the cd spinning after the lid closes:

Video of Laser lens focusing after being moved out manually and returning to home position the second time the lid switch is pressed:

Video of Laser returning to home position from bottom of player after being moved out manually:

 

[dr*audio]

The fact that the disc spins means that it achieved focus lock. Since it can't read TOC but the sled moves vindicates the motors. I think you have a bad laser. It puts out enough to get focus lock but not enough to read the disc. Liberty Electronics on e-bay has good replacements for Sony lasers.

 

[PE9ZZ]

First place to start in any CD player is eyepattern. If the laser's phut there is no RF signal. See service manual page 17. If you replace the laser before checking RF signal you will have to adjust it anyway so best start with that first.

 

[Alfmonster]

@dr*audio @PE9ZZ Thank you so much for taking the time to reply with such helpful advice!

The fact that the disc spins means that it achieved focus lock. Since it can't read TOC but the sled moves vindicates the motors. I think you have a bad laser. It puts out enough to get focus lock but not enough to read the disc. Liberty Electronics on e-bay has good replacements for Sony lasers.

This is so good to know. I was looking up replacements for the kss-121a and it seems scarce and also expensive - before taking the plunge, is it possible that there might be an issue with power going to the laser? Would it be possible to check this power issue using a multimeter? I’m relatively new to working on electronics such as these cd players - but I guess I’m very keen to learn how to.

First place to start in any CD player is eyepattern. If the laser's phut there is no RF signal. See service manual page 17. If you replace the laser before checking RF signal you will have to adjust it anyway so best start with that first.

Just checked the service manual - thank you for linking. I unfortunately don’t have a scope but I’m thinking of picking one up. Is there one you might recommend that’s affordable and good for this and other equipment of similar age?

 

[PE9ZZ]

Any 10 MHz or more scope will do. I have a €400 two-channel Siglent DSO but that may be a bit overkill. Many analog scopes can be found on the cheap. Tektronix and Philips made excellent analog scopes. I would stay away from the cheapo USB scopes as they have a crap UI. I bought a €40 or so (don't remember) Hantek and the thing was next to useless.

 

[dr*audio]

The fact that it completes focus search vindicates the power supply, but I wouldn't trust anyone but Liberty Electronics for the laser. I've never seen a KSS121a available. I think you are out of luck. KSS-150, KSS-210, KSS-213, KSS-240 are all available.

 

[Alfmonster]

The fact that it completes focus search vindicates the power supply, but I wouldn't trust anyone but Liberty Electronics for the laser. I've never seen a KSS121a available. I think you are out of luck. KSS-150, KSS-210, KSS-213, KSS-240 are all available.

That’s such a bummer! Yeah I haven’t been able to find a lot of KSS121a’s available. I might have to table this in hopes that one day I get lucky and find one.

Any 10 MHz or more scope will do. I have a €400 two-channel Siglent DSO but that may be a bit overkill. Many analog scopes can be found on the cheap. Tektronix and Philips made excellent analog scopes. I would stay away from the cheapo USB scopes as they have a crap UI. I bought a €40 or so (don't remember) Hantek and the thing was next to useless.

I’m not very hopeful this will be able to be fixed but thanks for the scope recommendations. I might check with a local college to see if I can use one of their scopes to check the RF on the off chance that might be able to tell me more info and look into one of the Siglent’s for purchase in the future. I’ll post findings once I’m able to get the reading.

 

[PE9ZZ]

Using that scope will give you insight whether you need a new laser or just a quick tweak. The manual is leading. Since it gets focus there is hope.

 

[Alfmonster]

Using that scope will give you insight whether you need a new laser or just a quick tweak. The manual is leading. Since it gets focus there is hope.

That’s good to know - I won’t lose all hope in the machine just yet. I checked again last night and it confirmed that there is a light that goes on for the amount of time listed in the service manual as it’s focusing.

Would increasing the strength of attenuator shown on pg 17 of the service manual be worth a try? Even without a scope just to see if it works? Perhaps I could use my multimeter or something to mark the current position and go up or down incrementally.
And if so, would it increase strength by turning counterclockwise and decrease strength by turning clockwise?

Also, are we talking very small movements?

 

[redk9258]

Would increasing the strength of attenuator shown on pg 17 of the service manual be worth a try?

No. Do not touch it! It is set from the factory. Increasing current will likely kill the laser if it is good.

 

[Alfmonster]

Thanks for the warning. Thats good to know, I’ll leave it alone.

 

[dr*audio]

Get a scope and look at the rf waveform when the disc is spinning. If it's between 1V p-p and 1.5V p-p the laser is good and maybe the tracking loop isn't closing. Possibly the E-F Balance needs to be adjusted but you need a scope to do that. So don't touch ANY of the adjustments.