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) this dirt?
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.
If you have a source of compressed air, it's a good idea to blow out all the dust (outdoors, of course). That way, you will get all the dirt in the nooks and crannies.
Beachcomber
I've always used a vaccum cleaner with the hose on the exhaust side with the crevice tool attached. I even restrict the air output with my hand or finger over the port to get more air velocity.
On Mon, 27 Mar 2006 15:07:34 -0800, Don Bruder Gave us:
Good response! Keep hands away though! Make sure to use a long handled feather duster as well as compressed air.
On Mon, 27 Mar 2006 19:03:04 -0500, William P.N. Smith Gave us:
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 it.
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 solvent!
On Tue, 28 Mar 2006 00:37:58 GMT, snipped-for-privacy@notreal.none (Beachcomber) Gave us:
Which is typically really all that is needed.
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 have been.
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.
Dave
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).
Chris
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.
On Fri, 31 Mar 2006 19:45:56 GMT, "I.F." Gave us:
Sound advice.
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! ;-)
--- sam | Sci.Electronics.Repair FAQ:
Nope.
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.
Dave
No war from me, I agree totally!
Dave
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.
Ed
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