Hantarex H-amp problem

[subcriminal]

Hello

I'm trying to put the finishing touches to my MAME cabinet but I've hit an irritating snag at the last hurdle.  I'm hoping one of you learned gentlemen can shed some light before I lose any more hair!

I'm using an ArcadeVGA card together with a Hantarex MTC9000 monitor from an old Operation Wolf cabinet.  I've connected up a video amp and everything looks crystal clear with no colour distortion or other problems.  Except...

The image is too wide to fit on the monitor!  I can easily control the vertical height of the picture via the V-AMP pot on the remote adjustment board.  However the H-AMP does nothing except make the picture move up and down a little!  I've replaced the H-AMP pot with one of the same value from elsewhere on the remote board, but it's had no effect.

Does anyone have any ideas?  I don't think it's the caps as the picture quality is otherwise flawless.

Any thoughts or advice would be greatly appreciated!

Andy L.

[Ken Layton]

If the monitor has not been recently recapped then do it. Hantarex monitors are well known for eating capacitors. The picture may look alright but there may be a couple of caps gone bad and you don't know it.

[subcriminal]

Thanks, i'll get a cap kit ordered then.

I found this article whilst trying to sort the problem:

"In parallel with the horizontal output transistor (between the collector and emitter) there is a capacitor called the "retrace tuning capacitor." A typical value for this capacitor is between 5,000 picofarads and 10,000 picofarads at 1,500 volts. Note that's picofarads, not microfarads.

To alter the width of the raster, all you have to do is change the value of this capacitor. A ten percent change in capacitor value will produce a proportional change in the width of the picture. Larger values will make the picture wider: Smaller values will reduce the width."

I have tried adjusting the Horizontal width coil near the LOPT with very little effect! I'll get a cap kit and a selection of retrace tuning capacitors then. Cheers.