Blast City Colours Dark in 15K...but looks great in VGA?

[noisuf]

Got my Blast City delivered today and looks great!

However, the colours are dark (even with contrast and brightness turned up)...even tried tuning the red, green, blue pots out the back.

On VGA mode though, it looks brilliant...very vivid. Why would the colours and brightness be different between 15K and VGA?

[Dave_K.]

Depends on what monitor is in the cab (could have been replaced), but it sounds like you are using the wrong input. Most tri-syncs have different VGA and CGA (15khz) inputs for exactly his reason since the RGB input voltages are different. How is the monitor attached to the Jamma harness?

[noisuf]

Just checked the monitor. I'm actually surprised it's NOT a Nanao. It's a Toshiba A68KZN696X. But I did a bit of researching and it may be the same as the tri-sync Nanao because Toshiba manufatured these for Nanao?

The monitor chassis is the original though as I checked it against the Bass Fishing manual.

I have the DC connected through the VGA input on the monitor chassis.

The monitor is attached to jamma harness via 839-0894 terminal (schematic attached). All original PSU and boards look present.

Attached are example pics of the brightness difference between VGA and 15K. First two pics are Ikaruga via DC VGA Box. Third and fourth pics are Raiden DX 15K. On 15K, if the turn the brightness too high, the screen goes too white. But I can't get the contrast going where the colours are bright. The same brightness and contrast settings are used for the first four pics.

Fifth pic monitor tube sticker. 6th pic is a blast city schematic.

Thanks!

[noisuf]

Happy endings all round...found the reason why 31K was darker, I needed to remove the vga plug from the Dreamcast VGA box!