Re: Help: fading IIGS monitor

[jpoore@pro-palmtree.cts.com (James Poore)]

You have one or two possibilities with the monitor.  1) The pix tube is bad
and 2) The voltage regulator is not regulating. 3) ok 3 possibilities
The video output stage is losing voltage.  The first thing to do is to
check voltages on the pix tube.  Kr, Kg, and Kb (red, green, and blue
cathodes) should read somewhere between 125 and 175 volts. G1 should read 0
volts, G3 should read anywhere between 100 and 800 volts (dependant on
screen control setting).  If voltages are ok then the tube is bad.  If all
voltages are wrong (all too low or all too high) The voltage regulator is
bad.  If only the cathode voltages are off the video supply is at fault.
Most monitor problems start from failing capacitors.  The heat causes them
to go bad.  A monitor has an average life of 5 years and then the
capacitors start goin which can have a domino effect on more expensive
parts (like the flyback transformer).  I have worked on Video game monitors
for about 20 years and I normally do a complete capacitor replacement every
5 years which keeps the monitor from going bad and also keeps the picture
quality as good as it can be.

Jim


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