Need help diagnosing CRT that powers on with no display

Started by Holering, August 24, 2013, 06:08:34 AM

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CRT monitor stopped showing display.   

Was working fine with PC until monitor went into standby mode (supposedly the monitor power off); monitor was in standby mode and I heard it make some very noticeable pop sounds about 5-10 seconds apart. 

The first couple times it went into standby mode, it took a couple minutes before it made even one pop sound and I thought it was just left over voltage escaping (though it was definately loud compared to usual crackling it makes when powering down so I was left wondering and kind of worried).  After the fourth time it went into suspend mode, it sat for a minute and started making pop sounds more often (each one was like 5-10 seconds apart more or less).  I immediately moved mouse to wake up monitor after feeling more uneasy this time and was left with a blank screen, though I could clearly hear the CRT power back on.  Restarted computer into bios and boot screen several times but still no display. 

Hooked up a different monitor to rule out a video card problem (I thought maybe the vga out stopped working since the CRT powered on) but this display works fine. 

After waiting an hour or so I tried the CRT again, but still nothing.  I'm clueless since I can clearly hear the CRT power up, and it makes the same static charge-up sound when a picture lights up on the screen (except it's completely dark, blank and seemingly off now); and it stays powered on.  There's no OSD (on screen display) anymore, which always came on when no connection was present; tried with vga cable unplugged.  It also displayed a degaussing message everytime I powered it on before it's current status. 

Since I'm not even getting low level display there's definately something wrong with a fuse or something shorted AFAIK.  Don't know which stage in a monitor causes the screen to actually light up with the display after everything else is ready.

Heard anode caps can go bad and leave a bad seal, allowing voltage to escape and cause popping sounds; also heard you can see sparks if it's dark enough.  I believe if this is the problem, it could've caused a short or hopefully just blown a fuse.  Can someone with experience confirm a leaky anode cap being capable of doing this when a CRT goes into standby mode?

I was suspecting some kind of voltage leak when I heard the pop sounds after standby mode so I suspected bad resistors, faulty ground (bad solder joints?) or bad shielding somewhere perhaps.  Don't understand what else could've allowed voltage to escape when CRT went into standby mode...

Also want to mention the horizontal width flickered really wide and out of place a few times when monitor was working.  It did stop flickering and it wasn't bad to begin with, and was able to run the CRT all day without it occuring again, before standby caused blank screen issue. 

While it did work, there was noticeable red becoming orange on lower left of screen and pink on lower right; this led me to think it needed degaussing.  Degauss did kick on with OSD message during power up, and I could do it through main menu, but everytime it only made a very faint click and very faint flicker after a 7-10 second wait, which is unlike most newer crt's that make a noticeable hum with a trembling screen that persists for anywhere from 7-10 seconds followed by a noticeable click.  I'm guessing the degaussing wasn't working?

Would be truly grateful for any help or ideas.

Kind regards,


Tried monitor again today but no luck.

I noticed, when switching resolutions the monitor makes the same static-charge up sound it used to when it worked (when a CRT display goes off and back on momentarily to switch resolutions, they always make the same static sound). I really don't understand what happened since it seems to be working properly with a blank screen.  Can hear it respond to resolution switches, pc power up and shutdown, and staticy sound changes proportionally like it should.

Don't know if this is normal but I don't feel any static on the screen either.


Sounds pretty fatal - I'd try a local TV repairman, hopefully it's just some old components that need replacing and no damage was done?


If you are getting the static startup sound, it means you are getting high voltage from the flyback transformer. Does adjusting the brightness up to the max produce any visible gray raster? Also is the heater working on the CRT? Turn the lights off and look at the neck of the tube, should be an orangy glow.