RGBS Output From Midway Arcade PCBs

[RGB32E]

I picked up a lot of arcade boards the other day and have noticed a similar issue regarding the RGB output on early 90s Midway boards.  The video output when connected to my Sony PVM-2030 is really dark with the following games: NBA Jam, Total Carnage, and Primal Rage. 

The cable I normally use to connect the RGBS output from the jamma harness has ~160 ohm resistors in series to reduce the video voltage level on the RGB lines (way too bright otherwise).  I built another cable without resistors, and the image did not appear to be much brighter, if at all.  I then tried connecting series capacitors on the RGB lines (220uf - negative end towards PVM) and the picture brightened significantly.  Can anyone explain with what is going on here?

[ken_cinder]

I can't say exactly why this is, but I CAN tell you that I haven't seen those Midway games in any less than a big ass cabinet with big bright monitor in the wild.
Maybe Midway decided to do this, based on the monitors they were pairing these boards with in cabinets they shipped out?

There is no standard within the Jamma standard, on video levels. The mfg will decide how highor low the output levels will be at default, and they could have chosen a lower level to avoid damage to sensitive displays or something?

btw, I'm pretty sure you can throw the service dips on these boards and adjust brightness. (My MAME cab PC is KO'ed right now, so I can't 100% this, but I recall as such)

[RGB32E]

While there are all sorts of picture settings for MAME and other emulators (e.g. Contrast, Brightness, Gamma), I've yet to encounter any picture settings of this sort.  While most games have a vertical flip dip switch, and a few that have sync polarity dips (e.g. Street Fighter The Movie), picture settings are left to the monitor, and not the PCB itself.

I think CRT monitors made for arcade handle RGB differently than the Sony PVM monitors.  Hence, I'm wondering if there's anything better to try than to filter RGB with 220uf caps.