Samsung SyncMaster 931 BF CCFL voltage only stays up for few seconds at turn-on and then randomly for a few seconds at a time--any simple fixes ?

All screens on earth do that, if the PC desktop is dead, all do , it goes to ITS very own sleep mode. and black screen in 15 seconds. after PC dies, or is PC already dead, not connected or cable to PC is bad. or both ends connected wrong..
#2 cause is CCFL backlamp tubes dead.
2007 year made has those CCFL and most are dead now. or even only 5 years old they die.

to prove that , CCFL deal. dead
when monitor is cold, and no Power
power it on (its button) only, no PC needed
and push the menu button under 15 seconds
does the OSD menu pop up, if yes monitor is not dead.
or do this test any time that" 20 times dead "thing happens, do the OSD test first.

CCFL deathh symptoms.
dead tubes, all or 1/2 the screen
dim tubes
intermittent, and random dead
fails only warm or cold, only. thermal.
yellow tinged tubes, white = yellowish.
bad luck and any CCFL can fail, for lots of reasons. we
use a flash light pointed at the screen to see , OMG there is data there. the menu button does work , only CCFL are dead.

now the acid test gee test the monitor on a 2nd known good PC.
what can be more easy and best test.
if that simple test works, then the PC#1 is dead, we then fix it next.
the secret is he OSD is inside the monitors brain, no PC needed.

danny tell your story and do the tests first

see data? ????? PC good, or OSD is up for 15 seconds,?


free manual

https://www.manualslib.com/manual/145335/Samsung-Syncmaster-920nw.html?page=11#manual

If you look at the screen at a sharp angle and you see a faint Windows image then the problem is a back light fault. This fault can be caused by a faulty inverter board that supplies high voltage to the CCFL lamp OR the CCFL lamp is faulty. The CCFL lamp is a very small diameter fluro lamp/tube and just before they fail completely they product a pinkish light.
Replacement inverter and CCFL lamp are available from this WEB site.
www.lcdparts.net

problem with power supply circuit or inverter and ccfl lamps..

problem with ccfl lamps, inverter or power supply circuit.. needs servicing..

Hello,

The picture board on your monitor has been malfunctioning for quite the period but you did not notice it, since the screen goes blank, it means the picture board of your monitor has developed fault and will need to be replaced.

The best thing for you to do now is to take the monitor to a local repairer within your vicinity to help with the replacement of the picture board because the fault is not something you can fix yourself, in order not to complicate issues.

Take care.

The backlight power supply maybe failing.

Try to boot the system with safe mode and check whether you are getting display. if yes, need to download latest driver for display card. if No, then check the monitor cable was properly connected or monitor may faulty. Replace/repair the same will solve your problem.

Also check the DPI and resolution configured in display properties.

Revert back for more clarifications or assistance required.

1. Check that you did not accidently bridge any printed circuit tracks when you replaced the caps.
2. Make sure you put the caps in the correct way round. (they can only go one way).
3.It may be that another fault cuased the caps to go - if so you will need to find this fault - it may be difficult if you have no test equipment.
4. The 35v caps are OK as long as the values are the same.

It is either the Inverter board inside or the ccfl is faulty. Don't waste time, not worth to repair.

i have the same problem