Continued problems with X797ES

[tubeboob]

I had my X707ES CD player serviced.

The laser output was tested and found to be working well within normal parameters.

The sled was cleaned and lubed and now the laser moves freely along its path with no obstructions.

Problem is now a little different than before.

Now when I put a CD into the machine a number of things may happen:

Sometimes it will play from beginning to end with no skips, no stops, just beautiful music.

Other times, it refuses to play at all.

It will always read the TOC. Then sometimes if I press play it will play the disc, and sometimes it will not.

Occasionally after reading the TOC the disc will spin backwards at a very high rate of speed. When this happens and I press play, it simply would not play. If it stops spinning backwards on its own and I press play, it will usually play the disc.

Other times the disc will stop spinning after reading the TOC. And if I press play, it will play properly.

When the disc is playing and I press stop, sometimes it will stop spinning, and other times it will spin backwards, sometimes fast and other times slowly.

When the disc is spinning very fast backwards and I press eject, the tray opens with the disc still spinning in the tray.

Other times, the tray opens with the disc not spinning.

Assuming that the laser is working properly, what other sources of these problems could there be?

The symptoms seem to be an electrical glitch, as I've never heard of a CD player spinning a CD violently backwards when "stop" is pressed.

I really love the sound of my ES piece, and I would love to get it working right.

Any tecchies out there?

Cheers

 

[ilimzn]

You may have a problem with an intermittent connector to the mechanism board, or indeed, a problem with the through-plating on the same board. The 'backwards spinning' ihappens when the player is trying to stop or slow down the disc but the servo circuits lose input from the laser, and are left 'hanging' with no feedbck that the disc has not only stopped but begun spinning backwards.
The mechanism board is controled by a microprocessor on board with the display and switches, fastened onto the inside of the front panel. There is a flat cable that leads to a connector in front of the AD board (behind the yop righthand part of the front panel) and it plugs into a mating connector with additional flat cable that goes to the mechanism (you can see all the conenctions to the mechanism by removing the bottom cover). If there is a bad contact here, the player 'hangs' and does all sorts of strange things when the disc is inserted, while at other times it will work just fine.
One thing to look at is the routing of the cables, that neither has been pinched somewhere. I have 3 of these CDPs (actually one 707 and two 779 which are in fact the same machine with insignifficant differences to some minor parts on the boards), and everyone has these cables routed differently!

 

[guiller]

You've got a good listing of common failures and tools for a good diagnostic here: http://www.lampizator.eu/LAMPIZATOR/TRANSPORT/laser/Laserology.html . Perhaps it can help you to identify the nature of the problem.

 

[dr*audio]

A couple things to look at. First make sure the rails for the sled were properly cleaned and lubricated. With the power off, tilt the unit front to back. The laser should slide quickly from front to back, all the way and not hang up anywhere. If not, clean the posts the laser slides on with isopropyl alcohol, then apply 2 drops of light weight machine oil to each rail. If the rails aren't cleaned the player can do funny things.
It is possible one of the adjustments, particularly the E-F Balance, can be off. You need an oscilloscope to adjust this.

 

[ilimzn]

IIRC the X779 uses a servo system with only one adjustment and I'm not sure it has the E-F balance, but this is from memory... the service manual is availabe at www.hifiengine.com...

 

[Jon_Logan]

It will have an E/F balance. It's used to tune the tracking E/F photo diodes balance relative to the main laser spot being centered on the track.

You said it can play through a whole disc fine. I'd wait a little bit on adjusting the trackig/EF balance for right now. Warren (Dr*Audio) raises a very valid point about the transport lubrication. If this is a linear motor sled (magnetically positioned and not gear driven), it's very important that the movement is very free and doesn't require much force at all to make it glide. Also, make sure that any rubber bumpers are clean and dry. The rubber can out gas and become sticky, "grabbing" the transport and preventing it's movement.

The linear motor transports from Sony, usually had an orangey flex connector (thin and flat) that connected the Base unit (optical block) to the servo board. Make sure that the flex doesn't touch the bottom panel as it travels from the center out to the far edge of the disc.

Since it does play sometimes. Close the drawer and watch the optical lens perform a focus search. It is hunting for the disc. The lens should pump up about 3 times
smoothly!! If there's any abnormal friction on the lens's voice coil bearing, you'll have unreliable reading.

 

[tubeboob]

Don't know why and I don't know how, but the player has been working perfectly now for about 5 days continuously.

Reads everything thrown at it.

Keeping my fingers crossed.

Thanks for all the input, will post if I need more advise.

Cheers

 

[Old_Tech]

Have you thought of running it on repeat for a day or so just to work in the lubricants? I think this may be what you are finding anyway.

Its great to see people chime in on these threads. There is a real need for that.