VGA->Arcade. (.7Vpp vs 5Vpp) Up the screen/cont/bright or build an amp? (Ken?)

[MonitorGuru]

As I eluded to in Oscar's review of the 25" chassis from Victor, I actually made my first attempt at interfacing a VGA card (running AdvanceMame) with an arcade monitor. (right now a Hantarex 900 13", but that doesn't matter).

Anyway, as most know, VGA cards output .7 volts pp for the signal and arcade monitors expect 5 volts pp.

I was able to get a quite satisfactory screen by upping the screen control on the flyback to just under where it starts showing retrace lines/fog, then adjusting the brightness and contrast to reduce bloom and provide good color balance. {side note: I found that the brightness actually changed color of yellow to orange, but I didn't do any other adjustments and this is on a crappy test bench monitor right now anyway}

So my question to Ken (the *REAL* monitor guru ) is to see what you think should be done...

Is it better to adjust everything on the chassis to accept the lower level of inputs, or would it be better to build an amplifier to bump the range from 0-.7v to 0-5v ? then feed that into the chassis?

The *only* real schematic I could find online was one at: http://www.mameworld.net/pc2jamma/hardware.html or this schematic below.



Is this a proper amp or is there a better circuit using some LMxxx chips instead?

Thanks!

[dabone]

uh,,, it has 6 transistors in that design.


Later,
dabone

[MonitorGuru]

Ooops, I was looking at a different schematic I found when I typed that.. DUH!  

Thanks

[Ken Layton]

Wells-Gardner states in most of their sales literature that their monitors can be optionally configured to accept .7 volt video levels. Contact the tech support dept.