Neotec NT-500dx no horizontal adjustment

[AlexHorse]

I recently bought a Neotech NT-500dx and it would power on but it took a bit to get going and when did the picture looked great but the image would randomly flicker between looking normal and then shrinking to about 1/3 the width of the screen with a pin cushion issue. I decided to put a cap kit in as well as replacing the filter cap and reflowed the solder on any spot where something plugged into the board or any component attached to a heat sink. After I got the cap kit installed it powers up immediately and the picture still looks great but now the pincushion issue is constant. I have tried the on screen adustments and you can set the horizontal size adjustment from 0-100 with no change in anything (exact same thing if you try the pincushion adjustment as well) and I was wondering if anyone had any ideas of where I can start to try and get this thing working. This game has been one of those projects that's been fighting me the entire time.
Thanks!

[AlexHorse]

Anyone have any ideas?

[MKFan4Life]

Hi. I think this is one of the VGA models, right? I haven't worked on one of these, but I have worked on a couple of standard res and medium res Neotecs. My Gauntlet Legends has a medium res Neotec NT2701 I believe.

It had pincushion and horizontal adjustment issues in the past, and I think it always boiled down to a single bipolar (non-polarized) capacitor between 4-6uF value. (You could use anything in that range and it would work). It ran SUPER-HOT and would cook itself. The first one I tried was a Radio Shack 85 degree-rated cap that baked & changed color from medium purple to totally black when it went out!

Look on the huge heatsink by the flyback. Is there a small circuit board there? On mine, it had an adjustable pincushion pot on that small pcb. The remote board for my chassis has a printed denotation for a pincushion pot, but it is not populated from the factory. If that cap goes out, there is no pincushion adjustment and, if memory serves, zero horizontal width control. Simply replacing the cap with a BP in the range stated restored both to normal.

The last time I changed mine, I went with a much higher quality and higher temp-rated cap from Mouser. Even bought a few extras since it did that to me twice.

It may not even be on your chassis. I think your model has a remote board with the little buttons and all on it, right? Those chassis models have several ICs. A few are on the neckboard, and I'm not certain if one of those might control your pincushion on that model.

Good luck man!!