Electronics > Beginners
Cleaning a CRT oscilloscope
vk6zgo:
--- Quote from: spec on November 21, 2018, 06:09:46 am ---
--- Quote from: james_s on November 20, 2018, 11:54:54 pm ---These days the CRT is one of the only parts I'm interested in from junk TVs, they're no longer made anymore and it will soon become very hard to keep the classic arcade games and vintage TVs going. B&W tubes are already getting difficult to find, the 23" tubes used in some of the early Atari games are pure unobtanium.
--- End quote ---
I didn't know that!. At one time you could get reasonably priced re-gunned CRTs of all types from a number of sources.
Are arcade games a hobby or a job?
--- End quote ---
With the disappearance of CRT using TV sets, the "bread & butter" work for these necessarily specialised
companies has disappeared, so that they had the choices of increasing their prices radically for the few remaining users of CRT based equipment, finding something else to do, or worst case, close.
spec:
--- Quote from: james_s on November 20, 2018, 11:54:54 pm ---Safety glasses?
Yes, not for injuries from "implosion", but if you are using compressed air, you might kick up something nasty & get it into your eyes.
--- End quote ---
Not sure what you are saying here and why.
I made no mention of imploding CRTs in my post.
You question the use of safety glasses and then say they protect your eyes from dust :-//
Just for the record, I now advise wearing safety glasses for pretty much any operation, from mowing the lawn, to electronics, to motorbike/car maintenance. And the reason is that your eyes are very delicate and easily damaged. I have had serious eye damage from doing the simplest things. While mowing the lawn a small splinter of wood flew off the cutter and entered my eye. And once while messing with a valve scope I got some very fine acidic dust in my eye that was as painful as hell for about a day.
And other people have got solder splashes in their eyes, one of the wiremen at work had a major incident with solder in is eye.
Just the other day a neighbor got a steel splinter in his eye while sawing a piece of iron by hand.
All of these injuries could have been avoided by simply wearing a pair of £1.50UK safety glasses.
But in my younger days I would have laughed if someone suggested wearing safety glasses, in fact safety anything :)
james_s:
--- Quote from: spec on November 21, 2018, 06:09:46 am ---I didn't know that!. At one time you could get reasonably priced re-gunned CRTs of all types from a number of sources.
Are arcade games a hobby or a job?
--- End quote ---
It's just a hobby for me (and most others) although there are a few people who restore and sell stuff as a job. Hawkeye was the last CRT rebuilder in the USA and they shut down several years ago when the owner retired. As far as I know, RACS in France was the last rebuilder in the world and they also shut down a few years later. The equipment from Hawkeye as well as a few items from RACS are now in possession of the Early Television Foundation museum in Ohio where they have been working to get it set up and some volunteers have been learning the art of CRT rebuilding. I haven't checked the status of all that recently but given the very small volume and the fact that electron guns are going to have to be either NOS or painstakingly crafted by hand, getting a tube rebuilt is going to be very expensive and only cost effective for valuable antique sets.
I forgot to mention there's another tube that is virtually impossible to find, the 19VLUP22 which is an oddball inline color tube with a 100 degree deflection angle and an unusual neck pinout, it was used in most of the Atari and all of the Sega color vector games. A complete monitor typically goes for at least $500 and the supply of replacement tubes dried up ~15 years ago. No other display technology can match the dynamic range of a vector scanned CRT, especially the B&W tubes. Modern flat panel displays look very out of place in the classic games too, it's like seeing a modern MP3 player in the dash of a 1950s car, it just looks weird and wrong.
nibo:
Hi all,
Sorry for the late reply. Lots of great information posted, I definitely didn't expect this much detail! Many thanks!
--- Quote from: spec on November 19, 2018, 08:52:42 pm ---Sounds like an interesting project- I am a bit of a scope addict and have messed with all kinds of scopes over the years. What model scope do you have? Any chance of a picture?
--- End quote ---
I'm afraid its nothing special, just a very basic Philips PM3208 (https://www.radiomuseum.org/r/philips_oscilloscope_pm_320800.html). Released in 1989 according to the linked page, so it's just about to turn 30 after all. Unfortunately, I'm not able to take any pictures of the instrument at the moment, since I'm away from my "lab" for a few days. I'll have to get back to you on that.
Your guide seems to be amazing! To tell you the truth, I don't yet feel comfortable doing the kind of work you describe :), so I'll definitely have to store the info and wait for my skills to build up. However, a question I have is that, unless I missed it, there's no mention of discharging the CRT or the electrolytic capacitors before doing any work. Is that because you think it is obvious, or because after leaving the scope unplugged for a day there won't be any dangerous charge left? (vk6zgo also mentions that in his message). If there's a need for discharging them, could please describe how you would do that?
Lot's of great info on CRTs in the replies also! So just looking at them won't kill you after all.
--- Quote from: TERRA Operative on November 20, 2018, 07:12:49 am ---Just be careful you don't clean off any markings on the knobs.
I know from experience that the black numbers on the dials on my Tektronics 2253 scope are soluble in iso-alcohol..... |O
--- End quote ---
Oops, too late for that for me :) Thankfully, the faceplate has survived my clumsy attacks with IPA!
Thanks again to everyone who took the time to answer.
vk6zgo:
--- Quote from: spec on November 21, 2018, 06:31:54 am ---
--- Quote from: james_s on November 20, 2018, 11:54:54 pm ---Safety glasses?
Yes, not for injuries from "implosion", but if you are using compressed air, you might kick up something nasty & get it into your eyes.
--- End quote ---
Not sure what you are saying here and why.
I made no mention of imploding CRTs in my post.
You question the use of safety glasses and then say they protect your eyes from dust :-//
--- End quote ---
Indeed, I said,""Safety glasses?
Yes, not for injuries from "implosion", but if you are using compressed air, you might kick up something nasty & get it into your eyes."
I was not "having a go" at you, it was more that the OP had specifically mentioned imploding, so I meant to point out that was not the reason you referred to them.
Sorry, it was clumsily phrased.
--- Quote ---
Just for the record, I now advise wearing safety glasses for pretty much any operation, from mowing the lawn, to electronics, to motorbike/car maintenance. And the reason is that your eyes are very delicate and easily damaged. I have had serious eye damage from doing the simplest things. While mowing the lawn a small splinter of wood flew off the cutter and entered my eye. And once while messing with a valve scope I got some very fine acidic dust in my eye that was as painful as hell for about a day.
And other people have got solder splashes in their eyes, one of the wiremen at work had a major incident with solder in is eye.
Just the other day a neighbor got a steel splinter in his eye while sawing a piece of iron by hand.
All of these injuries could have been avoided by simply wearing a pair of £1.50UK safety glasses.
But in my younger days I would have laughed if someone suggested wearing safety glasses, in fact safety anything :)
--- End quote ---
My then work became very much into safety glasses at one time, but the problem with the cheap glasses supplied was that their optical qualities were appalling, making soldering a lot of small connections incredibly tiring.
After a quite short time, they became scratched beyond usability, so had to be replaced.
They also soiled easily, so work fitted a glasses cleaning station with a fixed spraycan of glasses cleaner facing outward at eye level!
The cleaning solution was some sort of pungent smelling "devils brew".
We techs could see the obvious possibilities, so moved the cleaning station to chest height.
In later years, I began to need reading glasses, so normally wore them, instead.
I have found that, in situations where I am using power tools & the like, where more formal protection is necessary, that a full face visor is more comfortable, & it allows me to use my prescription glasses as well, if needed, without the possibility of damage to them.
I hate real goggles with a passion, but, of course, must wear welding goggles for oxy-acetylene work.
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