Need Help! No blue in WG D9200 monitor

[SuperNole]

I recently bought a sega naomi cab.  I took the World series baseball out and put in MvC2 now there is no blue showing.  Every other color is fine.  I disconnected the mobo and put it in another cab and everything was fine so its not the game or mobo.  I turned on the sega cab without a game connected and the No Signal shows a red block, then a green block and when the blue one should come up a black one shows instead.  Does anyone have a solution?  Thanks in advance.

[grantspain]

have you tried a different vga cable

[SuperNole]

have you tried a different vga cable

Tried 2 different VGA cables and got the same results.

[grantspain]

if thats a digital monitor then check the osd to see if some how the blue has been set to minimum,this would happen with pentranic digital from time to time

[Ken Layton]

If it's an early 9200 production then you are entitled to a free complete neckboard assembly from Wells-Gardner. Early production runs has a poor design neckboard causing color driver transistor failure. Telephone Wells-Gardner tech support in McCook, Illinois and talk to a tech. He can tell you how to determine what neckboard you have and if you qualify for the freebie.

Of course though this model regardless of when it was made is very trouble plagued. I'm sure you read the Wells-Gardner sticky thread didn't you?

[qrz]

with a static (non moving) pic , take a AC voltage measurement from the collector of the blue output xistor to ground.
if u have an AC voltage here , ( which should also be close to that of the red and green) it may be a weak gun ( crt)
if no AC , there is likely an issue in the blue processing  . check xistor(s) cap(s) from the input all the way to the crt pcb.

high esr on coupling caps will cause problems !


note : DC collector voltages are generally 100-200V  no signal

qrz