Bringing this thread back because I have a Commodore 1084S monitor that I took out of our attic because my interest in computers has resparked and I'd like to see if it still works.
I know some stuff about CRT displays and the hazards associated with them in regards to high voltage that can still be present long after the monitor has been switched off and unplugged. Well in my case, the monitor has been sitting without power for over 20 years so I doubt that there's still any voltage left inside. My main concern is that the electronics have sat unpowered for so long that they may no longer work.
Here's a photo of the monitor.
Yes it's tied up with Telstra Rope. I did this so I could lower it from the attic in a (mostly) safe and controlled manner without shattering the picture tube or falling off the ladder and having a computer monitor hit me a few seconds later.
Back to the monitor now.
I know how violent a CRT implosion can be. I've seen videos on YouTube that showcase how violent a CRT can be if it implodes. I also know that the flyback transformer and it's circuitry are where the high voltage that everyone warns everyone about is located and that discharging the capacitors and removing the suction cup from the tube is the first thing you should do after unscrewing the casing.
Lastly, whenever I'm working on something and feel that what I'm trying to do is outside my confidence level, I won't do it until I feel confident enough to do so or I have someone else who can do the work for me.
Hopefully I can get it working. My ultimate goal is to acquire a C128 system to use with the monitor as it was a very common combination for it's time.
Many of the warnings about implosion of picture tubes are a relic of the very early days of large (for then) CRT tubes, mainly WW2 military PPI RADAR displays, where the glass thickness was very much less than later tubes, partly for Wartime austerity reasons, but also because it was difficult enough to obtain sufficient brightness, even without the optical losses of heavy glass construction or heavy safety faceplates.
With the rapid development of domestic TV receivers, real world practicality demanded much more rugged tube construction, whilst, fortunately, coinciding with much more sensitive phosphors & more convenient methods of producing EHT.
For a number of years, these were combined with separate glass faceplates, then, coincident with the replacement of 17" & 21" tubes with 19" & 23" types, bonded faces were fitted.
The latter development was in the very early 1960s.
Later, "prestressed" designs were used, which concentrated any implosive forces away from the screen, into the very much smaller neck area, where the amount of glass available to possibly cause damage is much less.
After a general, but not close, association with CRTs for years, I changed jobs & became, as one of my duties, in charge of "Monitor Maintenance" at a TV Studio.
During my 10 years there, I worked inside many monitors & changed a large number of picture tubes.
The dead CRTs were taken out the back of the building & chucked (from a safe distance) into a large metal dumpster.
Mostly, the necks were broken on impact, with a gentle sigh, & that was that.
Some survived such treatment, so for those, we had a long length of metal "star picket" which we used to crack the necks, with the same gentle sigh resulting.
As the Commodore Monitor was a mid-late 1980s product, its CRT would have had all of the later developments included, as well as being a quite small tube to begin with.
As to EHT, if it is working, you have little reason to mess with it.
The manufacturers provide quite good insulation, so inadvertently touching it is most unlikely.
What you might encounter is the several hundred volts of horizontal or vertical signals on the deflection yoke, which can give you
a nasty surprise but are not a serious danger.
What really are the BIG "bities" are those places which are fed from the Mains, like the power transformer primary, if one is used, or more probably the SMPS (note; these also have nice big electrolytic caps charged to rectified Mains), & lastly, the thermistor in line with the degaussing coil.
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