Acer 77e Black Screen Until Warmed-up
 

This 17 inch monitor turns on and has HV but the screen is completely black
for about 5 minutes. Gradually, it brigthens up but the images look out of
convergence [?] - blurred, colors off, unreadable.

After about 30 minutes the picture is superb. OSD works fine.

No matter how long the monitor then remains in standby, it comes back
perfectly.

I'm guessing maybe a failing capacitor in the SMPS and will test with freeze
spray.

Any better clues/hints/suggestions to limit my hunt would be apprecaited.

Thank you.


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Hi John,
Look for a capacitor in the filment supply of the CRT. You'll probably
find one bad causing almost no filament voltage when the monitor is cold
and as it (the cap) heats up, the filament voltage slowly increases to 6.3
volts or close. Find the filament terminals on the crt socket on the neck
pcb then trace the apropriate wire back to the main PCB and you should
find the right capacitor pretty easily.

Hi John,

I agree... Many monitors create the heater voltage in the SMPS instead of
the flyback. Check the low voltage caps in that area. If you have an
isolation transformer, you could check the heater voltage when cold and
watch it as the monitor warms up. When working on live equipment, follow
the safety guidelines in the repair faq (www.repairfaq.org). Be carefull!
Most of the time, the live area will be well marked on the board.

Kirk S.
"techdrive" wrote in message
lkaboutelectronicequipment.com...
Hi John,
Look for a capacitor in the filment supply of the CRT. You'll probably
find one bad causing almost no filament voltage when the monitor is cold
and as it (the cap) heats up, the filament voltage slowly increases to 6.3
volts or close. Find the filament terminals on the crt socket on the neck
pcb then trace the apropriate wire back to the main PCB and you should
find the right capacitor pretty easily.

On Sun, 31 Oct 2004 16:52:19 -0500, "techdrive"
wrote:

Hi John,
Look for a capacitor in the filment supply of the CRT. You'll probably
find one bad causing almost no filament voltage when the monitor is cold
and as it (the cap) heats up, the filament voltage slowly increases to 6.3
volts or close. Find the filament terminals on the crt socket on the neck
pcb then trace the apropriate wire back to the main PCB and you should
find the right capacitor pretty easily.

Or start at the SMPS and identify the 6.3 VDC source, and replace its
filter capacitor.

Tom

On Sat, 06 Nov 2004 22:41:57 GMT, "Kirk S."
wrote:

Hi John,

I agree... Many monitors create the heater voltage in the SMPS instead of
the flyback. Check the low voltage caps in that area. If you have an
isolation transformer, you could check the heater voltage when cold and
watch it as the monitor warms up. When working on live equipment, follow
the safety guidelines in the repair faq (www.repairfaq.org). Be carefull!
Most of the time, the live area will be well marked on the board.

Kirk S.

Right... I have never seen a PC monitor that derived its filament
voltage from the FBT.

Tom

"techdrive" wrote in message
alkaboutelectronicequipment.com...
Hi John,
Look for a capacitor in the filment supply of the CRT. You'll probably
find one bad causing almost no filament voltage when the monitor is cold
and as it (the cap) heats up, the filament voltage slowly increases to 6.3
volts or close. Find the filament terminals on the crt socket on the neck
pcb then trace the apropriate wire back to the main PCB and you should
find the right capacitor pretty easily.