My PC monitor (17 inch glass tube) is about 4 years old and has
been used heavily. I took the cover off to fix a loose connection
because the picture was sometimes jumping.
Inside the circuit board was quite dusty and rather sooty. The
CRT tube and anything neary was very sooty.
----> Is there any merit in cleaning (hoovering or gently wiping)
At the voltages that can be running around in the back of a crt,
cleaning out accumulated "crud" is a damn good idea, since, as you say,
some of it may well be (semi)conductive.
Even if it's inert, it'll have a negative impact 'cause it's acting as a
blanket, keeping components hotter than they would be if running in
"free air" conditions.
Just make sure you know where the high-voltage connector is, and how
to discharge it, these things can hold a lethal charge long after you
unplug them... IIRC you want to clean around the high-voltage power
supply, lead, and tube connector with isopropyl.
On Mon, 27 Mar 2006 19:03:04 -0500, William P.N. Smith
It doesn't need to be discharged if he leaves the damned connector
alone, aside from cleaning it off with air or a duster! It is best NOT
to discharge it. The connector is usually well sealed, and one
doesn't want to break that seal. Also, the flyback current limit
resistor can be damaged, though should be designed well enough to take
Unplugging the AC line cord is one thing, but there is no need to
unplug an anode wire that is not already leaking!
He can merely use a duster brush, and compressed air for the entire
job. The goal is to reduce leakage form corona and reduce heat from
dust blanketing. No need to douse the damned OLD thing with a
Probably true, but if it's as grubby inside as the OP indicated, he
might have some (cooking) grease fallout in there, and might want to
properly clean around the HV parts, using care not to zap himself...
Try the dust removal thing first.
A high voltage shock from a CRT will definitely get your attention but
"lethal?" Only if your reaction the the shock causes you to fall out the
window or come into contact with something that's REALLY potentially lethal:
the line cord.
That's not to say that you don't take precautions. Getting a shock when
working on electronics is proof you haven't been as careful as you should
I tried to post much the same point but it didn't appear. The most dangerous
area of a TV or monitor is the mains smoothing capacitor, which is indeed
potentially lethal. I have never heard of a fatality from the CRT anode, and
it shouldn't be particularly hazardous to a healthy heart. The biggest
danger from the CRT anode is, as you say, secondary injury caused by reflex
action from the shock.
I wouldn't use any solvent, some solvents will disolve the aquadag (graphite
coating) off the back of the tube and you don't want that dripping all over
the EHT circuits. Better just blow the loose dust out, and maybe give it a
light and careful brushing (with a plastic handled brush if you're afraid
of the EHT).
One minor worry with compressed air if it comes from a compressor (as
opposed to a compressed air can) is condensation in the air hose, the water
droplets can be forced under components where they take a while to dry out!
If the air line doesn't have a condensation filter - blast it out for a few
seconds before pointing it inside the equipment.
Thank you all for your advice.
All this now makes me think that my TV (which uses a 19 inch glass
tube) would also show an improved oicture if it too had the dust
cleaned out of it.
Is this correct? Or does a TV differ in some way from a PC monitor
when it comes to getting visible improvements from dusting?
Let's take a survey.... How many of the professional techs, engineers,
and scientists who read this group actually do periodic cleaning of inside
of their monitors and TVs?
If you're obsessive-compulsive and have nothing better to do, by all
means clean the insides of your CRT equipment. But it's probably more
likely that something will get messed accidentally, than any significant
improvement in either performance or life span.
The high voltage area of modern CRT equipment is generally enclosed and
or sealed with HV grease or adhesive. It's not like old all-tube-type
TVs where everything collected an inch of dust if you turned your back. :)
Yes, dust does collect. And yes in principle that may affect something
eventually. But if there are no symptoms, leave it alone. It's not
likely that a gradually degradation in performance is dust related.
My approach about these things is that "if it ain't broke, don't
fix it". :) Seriously, if you're in a dusty dirty shop floor, then
there may be some benefit. But if it's a home or office environment,
don't you have better things to worry about than to clean the insides
of your 34,153 electronic gadgets????
For the record, I do not clean inside electronic equipment unless there is
a reason to go inside. My TV is 26 years old and I've repaired it twice
over that span due to defective chokes (probably a parts problem from the
supplier at the time of manufacture). Other TVs in the house are all more
than 15 years old and except one set of cracked solder joints, havne't
needed repair since I acquired them. I generally keep computer monitors
for 8 or 10 years without problems.
Let the flame wars begin... NOW! ;-)
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Neither will show a better picture by cleaning them out, it's nonsense!
Cleaning the optics in a RPTV may cure image issues if dust has worked its
way onto the mirror etc, but a direct view monitor or TV will be unaffected.
Have you actually cleaned inside one of your monitors/TV in order to
see how noticeable (or not) the change in picture quality is?
It might be wrong to dismiss cleaning if you haven't seen the
benefits on your own CRTs. Once you have tried then you could say it
is or is not worth the effort.
I've cleaned a lot of them, but never for the sole
purpose of seeing if it affects picture quality.
It does not. But there is the possibility of
damaging something. If there is some other reason for
opening the monitor up, and if you are careful, you
might as well clean it while you are there.
Unless your monitor is in a "hostile" environment where
it can pick up a LOT of dust/lint/dirt/whatever, leave
the damn cover on it and clean the outside only. In a normal
residential setting, the best you can hope for is that you do
not damage the monitor/TV in the process.