I don't know what unit this CRT goes with, but I can offer a possible
suggestion.

Look on the high voltage transformer assembly, or on the HV
multiplier, or on one of the CRT drive circuit boards. Look for an
adjustment called CRT bias, or Screen, or G2. Mark the position of
the pot so that you can move it back. Try the adjustment.


Jerry G.


On Nov 24, 9:54*am, wrote:
A few months ago I located a "new old stock" Sony F500R CRT.
It was bought as a spare for a corporation but had never been used
since its manufacture date of November 1999.

When I first started using the set, the picture was absolutely perfect,
until my nephew decided to see what the "auto restoration" feature
was for on the monitor. *Zip, zap, the picture flung around and then
resettled back down. *No harm, or so I thought.

Ever since, when I power on the monitor, the brightness is overdriven
and I cannot get a pure black level. *If I set the brightness to zero it's
pretty close. *After about ten minutes the brightness decreases rather
rapidly, and I have to manually adjust it back upwards to achieve a
proper black level, and it stays fine until it's powered off again, and
I have to repeat the same cycle all over again.

My two questions are,

1. What is the likely cause of this problem? *Bad caps, or is there
an internal way to reset whatever the "auto restoration" function did?

2. If the likely problem is bad components, is anyone reading this in
the Bay Area of California, and would you like to make some money
repairing it for me? *I can't say money is no object but I'm willing to
pay several hundred in labor costs to get the monitor thoroughly
tested and repaired correctly.

Thanks.