I have two GDM-F500 monitors with one acting up.

When it's turned on it shows a very bright white image with retrace lines
that gradually lessen in brightness then the image instantly snaps to
normal(this takes about 4 minutes).But the black background of the desktop
isn't a true deep black like the good monitor, rather a lighter black or
brownish color.

Then it will hold this normal picture for as long as it's left on.
Tapping on the 'A' board(Video Amp/ RGB Out) will cause the image to go
bright white again.Tapping it again will knock it back to normal again. I
resoldered all solder joints on the large chips and all other components
except for the surface mount components.

Tapping on the tube neck has no effect nor on the 'G' board(flyback
transformer) on the left side or the 'D' board(Deflection) on the right
side.
A magnifier lens didn't reveal any obvious fractures but I shotgun
resoldered everything anyway.

Could a surface mount solder joint be bad and if so, how do I resolder them?
with a special iron tool? At what wattage?
Or could a circuit board trace be broken? And if so, how do I locate it and
fix.


Thanks
Jimmy

Could a surface mount solder joint be bad and if so, how do I resolder
them?
with a special iron tool? At what wattage?
Or could a circuit board trace be broken? And if so, how do I locate it
and
fix.


Yes, but it's more likely you missed a through-hole one. Try a can of freeze
spray with a straw attachment and see if you can narrow it down a bit, good
luck.

You need the proper soldering system for properly working with surface mount
devices. You can get away with using a very fine tip type soldering station
with a thermostat control, so that it can be adjusted to the proper
temperature for the right type of soldering jobs.

By your description you still did not find the cold solder connection. It is
possible that there is a cold connection with one of the surface mount
components. It is also possible that there is a break on the board.

To service these types of faults it takes a lot of experience and knowledge.
Many times, the tech would let the problem stay in its defective state, and
use the service manual, scope, and meter to troubleshoot the related
circuits to locate the fault. This may give a better chance to find the
fault, rather than knocking and pressing around on the board.

--

Jerry G.
======


"jimmy martin" wrote in message
...
I have two GDM-F500 monitors with one acting up.

When it's turned on it shows a very bright white image with retrace lines
that gradually lessen in brightness then the image instantly snaps to
normal(this takes about 4 minutes).But the black background of the desktop
isn't a true deep black like the good monitor, rather a lighter black or
brownish color.

Then it will hold this normal picture for as long as it's left on.
Tapping on the 'A' board(Video Amp/ RGB Out) will cause the image to go
bright white again.Tapping it again will knock it back to normal again. I
resoldered all solder joints on the large chips and all other components
except for the surface mount components.

Tapping on the tube neck has no effect nor on the 'G' board(flyback
transformer) on the left side or the 'D' board(Deflection) on the right
side.
A magnifier lens didn't reveal any obvious fractures but I shotgun
resoldered everything anyway.

Could a surface mount solder joint be bad and if so, how do I resolder them?
with a special iron tool? At what wattage?
Or could a circuit board trace be broken? And if so, how do I locate it and
fix.


Thanks
Jimmy