Sony CDP-505 tracking adjustments, HELP!

[Duo]

I have a Sony CDP-C505, it works, but not all that well. A few CD's it will make ticking sounds on. It skips very very easily, even from vibrations from the speakers. I know that there are adjustments in the transport to improve tracking and current and all that. Does anybody know the specifics on my model? The transport has three seperate pots on it instead of the usual one...



Thanks in advance...


- Duo

[Duo]

Please, anybody???

[casouza]

I suggest that you buy a book on CD player repair and diagnosis.
First of all, clean the lens with a Lens cleaner CD (available at most computer stores).

To get you started, most transports have 3 trimpots that adjust tracking/skipping:
Laser focus
Laser tracking
Laser gain (don't touch this one)
What I usually do is make a test cd: cut 1mm wide strips of black adhesive tape and stick them to underside of CD, as 4 spokes.
Make sure that the spokes do not cover the TOC area (inner rim), or the test CD will not play at all.
Mark with a transparency fine point marker the position of all the trimpot wipers.
Play the test CD or a CD that is not scratched but skips.
Adjust the laser Tracking trimpot first to the left, until the CDP fails. Mark thet spot with a red dot. Return trimpot to original position.
Play CD and adjust trimpot to the right until CDP skips or stops. Mark that spot with a red dot.
Now position the trimpot wiper exactly between the 2 red dots.

Play the CD, if it still skips, adjust the laser focus trimpot following the same procedure.
You'll need a plastic screwdriver (used to align FM tuners).

If the Tracking and Focus adjustments don't fix it, your laser is near the end of its life. Turn the laser gain trimpot clockwise just enough to read the test disc and a few scratched Cds. Expect the laser to fail soon, this is just a temporary fix while you get a new laser unit (like biasing a weak tube).
I hope this helps.
BTW this may seem very non-scientific, but I swear I learned this technique with IBM, to adjust tracking of mainframe disk drives. Of course the test disk was different (but coincidentally we looked for a fish-eye pattern on the scope).
Good luck

[ashok]

Hi Carlos,
Thanks for your suggestions. I have a defective CD67 which might be fixable. Sometimes these kinds of solutions will be much faster than finding and looking into a service manual.
Thanks for reminding us of the simpler ' not so technical' solutions!
Cheers.

[fcel]

Carlos ... I like your suggestion!

[Duo]

Thankyou, those procedures are quite useful to me. Do you know which of the three in a sony transport are the tracking and focus?

I'll give the adjustments a try if I can figure out what pots are appropriate.


-- Duo

[ashok]

Duo, as a precaution note the position of all the three pots so that you can go back to the original position if you goofed.
Another method is to measure the resistance of the pot with a digital multimeter when the system is OFF. Measure it after at least 10 to 15 minutes after switch off so that all internal voltages drop to zero. Measure between slider and one end of the pot.
This makes it much easier to get back accurately to where you started. Note down all measurements with pot number "in a book". Preferably a book that will not get lost easily! Never on pieces of paper which always seem to disappear. As you will see in other posts on the forum , you are really lost if you can't get back to where you started.
Cheers.

[Duo]

Thanks for the pointer. Still... Can anyone tell me which pot is which? I don't want to mess with the laser current unless I need to .

[jean-paul]

If there is no text near the potentiometers you better buy a manual. I like the empirical method described above but measuring the pattern with a scope is a more precise method and the one Sony recommends itself.

[Duo]

I actually found that the markings for the pots were under a label. I simply had to remove it and found the markings were
TB, FB, and APC. I figure TB is tracking and FB is focus while APC would adjust the laser current...