Re: Dell Trinitron 17" flaky - worth repairing?


"Van Chocstraw" <vanchocstraw@xxxxxxxxxxxxx> wrote in message
news:T5aWe.595$gE7.354@xxxxxxxxxxx
> I've got a Dell Ultrascan 1000HS Model D1025TM that was manufactured in
> May of 1998. It's quite similar to the Sony CPD-200GS (17" Trinitron
> tube) without the audio. I'm the original owner and have had no problems
> with it for 7 years until last week. The picture was fine, no shaking, no
> blurriness, warm-up time around 20 sec., no dimness, no strange sounds,
> nothing. It was perfectly fine.
>
> All of a sudden last week I turned it on one day and after about 10
> minutes the screen went black. There was no change in the picture before
> this happened. At the same time the picture went black the green light on
> the power button also went out. It didn't change to amber, or start
> blinking. I did hear a relay click out, as is normal when you shut it
> off.
>
> About 3 or 4 seconds after going black, it seemed to go into its initial
> power-on startup sequence again. The degaussing relay kicked in, I heard
> the static hum, then the other realy clicked, the green light on the power
> button came on, the degaussing relay dropped out and it seemed to be
> warming up again. But instead of completing the startup sequence, after
> about 5 seconds the green light went out again and I heard the relay click
> out again. This cycle then repeats itself over and over. At power-on, 3
> relay clicks and the light comes on, then after a few seconds the green
> light goes out simultaneously with a relay click. Lather, rinse, repeat.
>
> If left off for an hour or so it will power on normally and display its
> usual crisp, clear picture. There are absolutely no defects in the
> picture. Brightness, contrast, changing screen resolutions on the PC
> (800x600, 1024x768, 640x480) all work normally and the picture is fine.
> But after it warms up, *click* and the light goes out and the
> startup-shutdown cycle starts again.
>
> I unplugged the video cable from the PC to see how the power-on self-test
> would go and it came up normally with the "No Video Signal" message and
> the color bars, so that test passed.
>
> I'm trying to decide what to do.

There are some *lethal* areas inside a monitor, especially the mains side
reservoir capacitor, and some *painful* areas, like the CRT anode and focus
supplies, which may result in severe involuntary muscle contractions causing
serious injury or further electroction.

If you are competent to go inside with the power on-

Arm yourself with a can of freeze spray and a hair dryer/heat gun with a
small nozzle. From cold, power up the monitor and see if carefully heating
any section of the circuitry narrows the fault down. When it shuts down, try
cooling each component in the area and try powering back on until you find a
thermally defective semiconductor or capacitor.

Failing that, personally I wouldn't recommend spending money on repairing a
7 year old 17" monitor, it just isn't worth it IMO.

Dave


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