Polo screen gets bigger when bright.

[Witchboard]

When a dark image is on the screen it's fine, but when I bright image comes on where the screen is mostly white it seems to expand.  I figure a cap kit, but thought I would ask before diving into it.

[IntruderAlert]

I think my Polo does that too

[Witchboard]

Well... at least we know it's typical behavior. 

[IntruderAlert]

or maybe we both need cap kits

[Witchboard]

Yup.  It's not too annoying and I'm not sure I want to pull the chassis at the moment.  It would help to know if a cap kit would fix it, or if it's a tell tale sign that the flyback is on it's way out since that seems to be a typical problem with this monitor.

[AndyWarne]

This is caused by poor regulation of the B+ voltage in the monitor. The brighter screen takes more current which pulls down B+ and lower anode voltages on the CRT makes for a wider scan.
It might be a monitor design shortcoming. Possibly a cap kit might help though.
Andy

[IntruderAlert]

I'm just using the 1v output from the ArcadeVGA which is supposed to be enough for the Hantarex according to what I read on the Ultimarc site.

But could that be part of the problem?

[Witchboard]

Thanks Andy.

[IntruderAlert]

Well, I ordered a cap kit but I'm still wondering if the 1v signal is really enough for the Hantarex

[Witchboard]

I ignorant about signal strength, but mine is in use with a game PCB, not a MAME computer.  From this I would conclude that your signal strength is probably fine.