Advice wanted: running crt filament w/extrnal power supply

[Chuck Chandler]

I bought a $5, 20"monitor, it was on again/ off again. then it was off
again/off again.
It's fairly new, and has about 10 parts/ square inch by the time the
filament heater gets to CB w/ flyback, and I have no schematic, so....
I tapped off the CB w/ flyback and cut the original traces and am running to
externally located bench PS, 6.00 volts, 0.4 amps, full floating, properly
grounded, works fine. I also tapped off the power switch w/ intentions of
installing a wall-wart power supply inside the plastic but outside the EMI
shielding.
I think that will be easier than finding the real problem, as the crt heater
is marked plus and minus and when the monitor was working it seemed to drop
to 5.3 volts when it went into energy saving mode. No bad solder joints on
board visible.
Any suggestions or warnings will be much appreciated.
Thanks,
Chuck Chandler
Blacksburg, VA.

 

[Arthur Jernberg]

I may work fine if you can locate a useable area to mount a filament
transformer within the existing case. Otherwise it would probably be better
to actually find and repair the actual cause.
"Chuck Chandler" <sixaxis@blacksburg.net> wrote in message
news:bfk3sl$99op$1@news3.infoave.net...

I bought a $5, 20"monitor, it was on again/ off again. then it was off
again/off again.
It's fairly new, and has about 10 parts/ square inch by the time the
filament heater gets to CB w/ flyback, and I have no schematic, so....
I tapped off the CB w/ flyback and cut the original traces and am running
to
externally located bench PS, 6.00 volts, 0.4 amps, full floating, properly
grounded, works fine. I also tapped off the power switch w/ intentions of
installing a wall-wart power supply inside the plastic but outside the EMI
shielding.
I think that will be easier than finding the real problem, as the crt
heater
is marked plus and minus and when the monitor was working it seemed to
drop
to 5.3 volts when it went into energy saving mode. No bad solder joints on
board visible.
Any suggestions or warnings will be much appreciated.
Thanks,
Chuck Chandler
Blacksburg, VA.

 

[Dave D]

"Chuck Chandler" <sixaxis@blacksburg.net> wrote in message
news:bfk3sl$99op$1@news3.infoave.net...

I bought a $5, 20"monitor, it was on again/ off again. then it was off
again/off again.
It's fairly new, and has about 10 parts/ square inch by the time the
filament heater gets to CB w/ flyback,

Sorry for being dense, but what do you mean?

Dave

 

[Mike Berger]

By usable area, he means one far enough away that the magnetic field from the
transformer doesn't affect the CRT image. That could be very difficult.

Arthur Jernberg wrote:

I may work fine if you can locate a useable area to mount a filament
transformer within the existing case. Otherwise it would probably be better
to actually find and repair the actual cause.