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From: Paul on 29 Jan 2010 14:38
I.C. Koets wrote:
> My monitor (a DEC 21" CRT, older than dirt) has started to give sharp,
> static-discharge type audible ticks, which are accompanied by short
> distortions of picture and dimming. The picture distortion lasts for a
> refresh cycle, the dimming can take a few cycles to disappear.
>
> When I power off the screen, I hear a number of these ticks happening,
> one after the other, tapering off.
>
> Where do I begin to look for a solution? Google has not been much help.
>
> Thanks!

If you want a safe experiment to try, try changing the resolution
settings to the monitor.

I have a Trinitron, and it started arcing when the resolution was
set to 1280x1024 @ 75Hz. If I changed the resolution setting of the
video card to 1024x768 @ 60Hz, the arcing would stop. The monitor
compensates for the way it is run, and the operating voltage seems
to change as a function of the resolution and refresh rates
used. I even noticed the monitor ran cooler, with the lower
resolution setting.

You can try that as a workaround, until you can get another monitor.

A TV repair man would know how to fix that problem, but
the real problem for him, would be getting parts. Mine
needs a new flyback, but that ain't gonna happen. My
CRT languishes in the basement now, with an LCD to take
its place.

By me posting this link, this is not an invitation to go inside
the monitor. This is just so you know what a flyback is.
Really, they should stick a picture of a skull and crossbones
on the thing, so you'll stay away from it :-) The rubber
boot on the red wire, is to prevent corona.

http://en.wikipedia.org/wiki/Flyback_transformer

I've actually used one of those, to build my own high voltage
power supply. The most remarkable thing about that, is
I've never managed to give myself a shock :-) :-)
Talk about lucky...

Paul
From: philo on 29 Jan 2010 16:34
Kyle wrote:
> On Thu, 28 Jan 2010 21:01:30 -0600, philo <philo(a)privacy.net> wrote:
>
>> I.C. Koets wrote:
>>> My monitor (a DEC 21" CRT, older than dirt) has started to give sharp,
>>> static-discharge type audible ticks, which are accompanied by short
>>> distortions of picture and dimming. The picture distortion lasts for a
>>> refresh cycle, the dimming can take a few cycles to disappear.
>>>
>>> When I power off the screen, I hear a number of these ticks happening,
>>> one after the other, tapering off.
>>>
>>> Where do I begin to look for a solution? Google has not been much help.
>>>
>>> Thanks!
>>
>>
>> That's a hi-voltage breakdown
>>
>
> Exactly!!!! don't touch anything.. I hope he will not follow your
> suggestions, while I know you want to help... hi-voltage can kill!
>
> Bring the monitor to a qualified lab, if the reparation cost is too
> much, just buy a new one.
>
> New monitors are really cheap considering the models of years ago and
> you can have a quality replacement without spending too much.
>
> I suggest to just buy a new monitor...
>
> --
> http://shop-for-computer.com - Best Pc Deals, Refurbished Deals
>
> http://shop-for-clothes.com - Shoes, Handbags, Shirts, Coats
>
> http://shop-for-car.com - Huge Car Deals, Auto Parts



Now that everyone is getting LCD's those crt's are a dime a dozen

I can get all I want free...

so I rarely bother with fixing them...
From: larry moe 'n curly on 29 Jan 2010 18:15


I.C. Koets wrote:
>
> My monitor (a DEC 21" CRT, older than dirt) has started to give sharp,
> static-discharge type audible ticks, which are accompanied by short
> distortions of picture and dimming. The picture distortion lasts for a
> refresh cycle, the dimming can take a few cycles to disappear.
>
> When I power off the screen, I hear a number of these ticks happening,
> one after the other, tapering off.
>
> Where do I begin to look for a solution? Google has not been much help.

Try Googleing "monitor repair" because there's a lot of information
about this, including from the great electronics repair FAQ:

http://www.repairFAQ.org (especially read its safety
information!)

Also try Google Groups, namely sci.electronics.repair because there
are lots of smart technicians there, including the editor of the
electronics repair FAQ.

There are some monitor repair forums, including at:

http://www.BadCaps.net

Safety warnings:

#1: Don't work on the monitor unless you understand the hazards of
high voltage and how to deal with them.

#2: Unplug the AC power! You greatly improve the safety by leaving
the AC unplugged.

#3: Glass breakage may be more a hazard than electric shock. CRT
monitors have almost all their weight centered about 2" from the front
of the screen, meaning they can easily fall forward, so don't set the
monitor upright on a soft surface, like a bed. One person did that
and his monitor fell to the floor and broke the glass, but fortunately
the cabinet and the laminated safety shield on the front prevented any
violent implosion/explosion from shooting out shards. If you work on
the monitor, either place it on a hard, perfectly horizontal tabletop
with a pillow in front to catch the monitor if it falls forward, or
set the monitor face-down on some padding.

#4: Do not unplug the big suction cup on the side of the CRT because
that's a high voltage (30,000 volts) connection and retains high
voltage forever (and even if you discharge it, the charge comes
back). Actually the shock harzard from this isn't that bad, but when
people get shocked they often jerk their hand, either voluntarily or
involuntarily, and cut it up or hit the CRT and possibly break glass
(see implosion/explosion warning above).

#5: It's possible to get a shock of a few hundred volts from other
parts of the monitor, such as some big capacitors in the main power
supply and horizontal output section (also a power supply), but those
capacitors almost always discharge to zero in a few seconds. If they
don't, then the shock is probably more dangerous than the higher
voltage one from the CRT.

#6: There is NO radiation hazard, and anybody who says otherwise
either thinks your monitor was made before 1972 or is a complete
idiot.

The ticking sound may be from a short in a coil, such as the one
around the neck of the CRT, and maybe it can be fixed by coating it
with some oil-based varnish, after blowing it off with air or some
electronic parts cleaner (auto parts stores, electronic supplies,
Radio Shack -- get the stuff that does not leave an oily film, as
tuner cleaner often does). Let any parts cleaner dry for a couple of
hours, in a warm room, before varnishing. If the bad coil is the
flyback transformer (the chunk of plastic with the thick cable going
to that suction cup on the CRT), then you should probably junk the
monitor, unless you just happen to have an identical monitor (same
chassis; doesn't have to be same brand or model) with a completely
different and expensive defect with it.

Never overlook bad solder joints, which are often around heavy
components (like that flyback transformer), hot components (big
resistors, big transistors, or anything attached to a heatsink), and
connectors. Those joints may be bluish or dull from heat, have
hairline cracks (invisible except under magnification), or were bad
from the beginning because their wire leads were dirty (each joint may
look like a ball).

Look for burn marks and dark areas on the circuit board. Resistors
can turn brown or even crack open from heat. Electrolytic capacitors,
which are aluminum cylinders covered with plastic shrink wrap,
sometimes bulge or rupture on top or leak on top or bottom, but they
can go bad without showing any physical signs.

If you don't feel like repairing the monitor, at least try to give it
to somebody who'll give it a try because most repairs aren't that
difficult, and it would be a shame to waste something that may need
just a simple, cheap fix. Out of 12-15 junked CRT monitors I've found
on the sidewalk, I was able to repair all but one of them (a real
stinker -- literally like burning plastic), and I'm no expert.

From: larry moe 'n curly on 29 Jan 2010 18:17


Kyle wrote:
>
> Bring the monitor to a qualified lab, if the reparation cost is too
> much, just buy a new one.

Lab? The last person I heard call a monitor repair place a "lab" was
someone who thought monitors had to be repaired in clean rooms.

What did you really mean to say? ;)

From: larry moe 'n curly on 29 Jan 2010 18:25


John Corliss wrote:
>
> CRTs, especially old ones, should be recycled at this point. They're not
> worth trying to save when they go out.

The best way to recycle electronics is by repairing it and keeping it
in operation. Other recycling is a joke and dumps lots of hazardous
waste into the environment, contrary to what the recycling industry
would like us to believe otherwise. Most monitor repairs are simple
and cheap to people who know how to solder and operate a volt-ohm
meter.

> Working on a CRT, as others in this thread have warned you, can get you
> killed if you touch a high voltage capacitor for instance. Not only
> that, but if you actually succeed in turning on a CRT with it's cover
> off, you will be exposing yourself to dangerous radiation. Seriously.

You're right about the shock hazard but are completely wrong about the
radiation, unless you're referring to ancient color monitors
containing high voltage rectifiers consisting of vacuum tubes rather
than silicon diodes, and no way will the PLASTIC cover of a monitor
(usually the only cover there is) provide any protection against
radiation. Where did you get your gross misinformation about the
radiation, and why do you believe it?

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