Unit was working fine until recently. Towards the end of a side audio will cut out, shortly followed by skipping and eventual frame repeating.. This happens on all disks that i try. including my copy of Jurassic park. Which worked great 2 days ago...any ideas?

From what I've read it sounds like multiple issues could fix it.

Could be a belt, could need new grease on the rails, could be a bad batch of discs that are warped, could be alignment needs to be adjusted, could be dirty laser,
and a few other things I can't remember.

But try with the easier ones first, if you start adjusting stuff and don't know what you are doing you could cause more damage than needed.

I'm no tech and you must do any and all repairs at your own risk.
Good luck.

I already replaced the belt. Which solved all the loading issues. I suppose that I'll pull her apart, clean and lube again. And see what happens..

Suppose that I should start looking for a service manual. I imagine that will be required if it needs alignment.

In order to do it properly you need a test disc and scope.
But you can do fine adjustments and take a risk to get it working.
Make sure your discs are flat before you start any adjusting, sometimes warped discs can cause these issues.

I have also noticed that crosstalk has gotten alot worse recently. Any idea where the tilt pot is located on this unit? I found the manual for a 503, but not a 502..

Sorry I don't, but they should be very close to the same player, the 502 should be the same layout as the 503.

They will be small and possibly white or even metal looking.
And from what I remember in my 3070 they will say tilt or have a small Tfocus? I believe.

Also I can't emphasize enough. Make sure you need to adjust before you start to adjust.
These players while sometimes can get off track they really don't just need to be adjusted like a record player or such.

If it was fine for a long time and just recently developed significant issues you should make absolutely sure there is nothing mechanically wrong with it before moving any pots.

Cleaned an lubed the rails with white lithium grease. Removed some caked grease from head assembly gears, replaced with fresh. We appear to be back in business.

Crosstalk is horrible though. I have tilt gain, b tilt gain, and tilt offset. I'm going to research some more before I touch anything. I did clearly mark the pot orientation on all the pots already in anticipation of future fiddling.

Probably not. The 502 was an Alpha Turn unit and the 503 was the first Epsilon Turn w/ the separate CD tray. Thus, they would have significant design differences.

You could look at a 501 and it will be close, the change from the 502 to the 503 was big.

well it happened again, but this time every time it skipped. the display noticeably dimmed...over and over.weird..

this is gonna be fun to figure out...

Sounds to me that you’ve been having a power supply issue all this time if the skipping coincides with dimming on the display.

I would examine the power supply board and starting looking for leaky and expanded capacitors (the tops will look like they are bulging out).

Is the behavior any different if playing the flip side of the inserted disc?

I have verified a problem with the alignment, the display dimming seems to just be a byproduct of the issue. although i have measured significant drift on the power supply caps . it will be fixed eventually.

I picked up a Pioneer Elite cld-95 yesterday and i cannot believe how great the picture is, and how bad this d502 was....my whole pile of "rotted" disks are playing fine on the 95.

i spent a long time trying to find a good copy of Jurassic park. turns out that i was the problem all along, the player was the issue. not the disks.....i now have 4 copys of jurassic park...all are wonderful on the 95

i cant believe i thought my D502 was working fine other than my intermittent mechanical issues...i guess thats what i get for being a newbie to working on solid-state equipment.

having a good laugh on my own behalf right now....lol