Tech: 4900 blue screen?

[Guest]

Archived from groups: rec.games.video.arcade.collecting (More info?)

what would cause a total blue screen(like Qbert colored) on a k4900 without
anything hooked up? capkit was already done! is this normal problem for
4900?

every monitor should be totally black/blank(given brightness isn't too high)
without any video wires plugged in, correct?

blue drive pot broken? if so, where is the blue drive pot? i see the red
and green on neckboard but no blue. this is a totally solid blue screen!

Ken(my savior), where are ya? help!

TIA
Kelly

 

[Guest]

Archived from groups: rec.games.video.arcade.collecting (More info?)

Would that be the blue transistor on the neck board gone bad?
Just a guess.
-Tim

 

[Guest]

Archived from groups: rec.games.video.arcade.collecting (More info?)

ive had a blue screen before, it turned out to be a cracked
'neckboard'.

jon
http://www.arcade-classics.com

 

[Guest]

Archived from groups: rec.games.video.arcade.collecting (More info?)

There is no blue drive adjustment on the 4900.

VR401 is red drive
VR402 is green drive
VR403 is red cutoff
VR404 is green cutoff
VR405 is blue cutoff

If screen is solid blue (bright) then you could have a SHORTED/LEAKY
Q403 transistor.

Double check the black level control and/or the screen control is not
set too high.

 

[Guest]

Archived from groups: rec.games.video.arcade.collecting (More info?)

if that transistor failed, wouldn't that have no blue color at all though?


"mudmantim" <mudmantim@sbcglobal.net> wrote in message
news:1110194056.352228.85460@f14g2000cwb.googlegroups.com...
> Would that be the blue transistor on the neck board gone bad?
> Just a guess.
> -Tim
>

 

[Guest]

Archived from groups: rec.games.video.arcade.collecting (More info?)

Of course, a tube tester will reveal this most easily, which is why I bought
one. I have found that a rejuve will cure some heater shorts.


"matt" <gamefixer@gmail.com> wrote in message
news4SdncGY95T2H7HfRVn-vA@starstream.net...
> I'm not sure why no one is touching on what it probably is... A bad
> tube.... 4900's are notorious for this.