Monitor SONY G400 Brightness Spasm Problem

[CAW]

Monitor SONY G400 Brightness Spasm Problem.

The above monitor has been experiencing a spasmodic variation in
brightness for the last 6 months. The problem initially was only very
subtle but over the last few months it has got worse. The normal
brightness seems to be OK and can be adjusted with the control. When
the problem occurs the overall screen starts to become dull until I
rock the case back and the correct brightness returns. Some days this
never occurs - others it can get down to almost half brightness. The
geometry and purity of the screen does not vary with the fault and I
am sure it may be just a dry solder joint. I have the experience to be
able to repair the unit but because the monitor is crucial to my
business I do not want to be without it too long.
If someone can point me in the right direction as to where the fault
may be located it would be greatly appreciated.

CAW

 

[John Gill]

CAW:
It sounds like a bad solder connection.
Next time it happens, give the side a good swat with your
open hand. If it fixes the screen, open it up and look
for bad solder connection. Don't forget to also check
the circuit board on back of the picture tube.
John

 

[GPG]

Chck A1 voltage, filament voltage.