Compaq FS740 (Canadian) PSU repair

[Brian]

Hi,

I have a FS740 17" monitor (2001 Canadian model) which won't turn on.
The LED changes to green when the power switch is pressed, but thats
as far as it gets - no display. I think that the HV turns on for a few
hundred milliseconds and then shuts down. Any suggestions as to what
components I should check (or help in getting a schematic diagram)
would be great. I have done a basic inspection for dry joints on the
PCB, and all looks ok.

Thanks,
Brian

 

[Brian]

Hi, a brief follow up to what I wrote about the Compaq FS740 17"
monitor:

1) The power LED goes to on/off and standby in the absence of a signal
from the PC as expected.
2) The CRT heater is functional.
3) The EHT SOUNDS like it is working (static).
4) Degaussing circuit works.
5) I have re-soldered nearly all points on the main PCB.

There is still no sign of anything on the display.... No flashes, no
glow, no on-screen display.... Help!

Brian.

 

[Jerry G.]

Compaq like the rest of the monitor manufactures will not supply any
schematics or parts to outside servicers.

The thing that I would do, is feed it a known signal and trace through
the signal path with a scope, to see where it is getting lost. Since you
have high voltage, the CRT is lit, and the power supply seems to be
working, I would assume that somewhere, the video signal processing is
failing somewhere.

If you have absolutely nothing, including no brightness, you may have a
failed picture tube, or not the proper bias or supply to the picture
tube. Check this out as well.

--

Jerry G.
======

Hi, a brief follow up to what I wrote about the Compaq FS740 17"
monitor:

1) The power LED goes to on/off and standby in the absence of a signal
from the PC as expected.
2) The CRT heater is functional.
3) The EHT SOUNDS like it is working (static).
4) Degaussing circuit works.
5) I have re-soldered nearly all points on the main PCB.

There is still no sign of anything on the display.... No flashes, no
glow, no on-screen display.... Help!

Brian.

[email protected] (Brian) wrote in message