Turbo Sega - funny cars behavior :O

[vernimark]

yesterday I tested my TURBO. I just switched on the cab and I didn't try any troubleshooting at the moment so everything could be the cause of this.... this... strange behavior

https://www.youtube.com/watch?v=SikhA6IW5wg

actually this problem affects all the perspective calculation, not only the cars. You can see the trees and the buildings close to the cars are "longer"
 I don't have any experience on this board, only an easy fix. Do you have any idea?

[ataritoobin]

I believe there are pots somewhere on the PCBs that control the scale of the objects.  Perhaps it's something simple like one of those pots being dirty?

I couldn't find a manual online, but I'd refer to the manual/schematics.

Here's an adjustment sheet: http://www.arcade-museum.com/manuals-videogames/T/Turbo%20Adjustments.pdf
And the schematics: http://arcarc.xmission.com/PDF_Arcade_Manuals_and_Schematics/Turbo%20Schematics.pdf

[vernimark]

wow I can't believe scaling is controlled by pots.. I'll check saturday once I have access to the machine.
Really thank you!

[vernimark]

pots were ok, the same for the entire 3D circuit. I had some oxide on the power connector...

This oxide caused another problem, this time permanent. 2 cars glittered in the middle of the screen. This is a movie of the problem
https://www.youtube.com/watch?v=Zavb75Ls7po

Then I checked all EPROMS but all of them were ok. Removing Eprom by Erpom I understood that
EPR 1248 is dedicated to violet and green cars
EPR 1247 is dedicated to yellow and blue cars
this is a movie with the EPR1248 removed
http://youtu.be/MAIIqsHF9Us

swapping those Eproms, cars swapped positions too but the problem persisted on violet and green cars so I checked again the Eprom but the checksum was ok.

Anyway I burned again the EPR 1248 and the the game returned to play in the right way.