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We had a bunch of these monitors back in the day, don’t remember any of them dying early. I was always afraid of taking apart CRTs thanks to those transformers in them. People used to overclock monitors back in the day to increase the refresh frequency.
Earlier quoted context omitted.
I've always wondered why modern multimeters don't have a "discharge" option. I.e., you select the discharge mode, put the probes on a capacitor, and watch the voltage go down, while an internal current limiter makes sure that it happens at a safe rate.
The probes aren’t big enough. That’s why it’s often a big screwdriver and jump lead to earth. The better option is the Fluke 80K 40. https://www.fluke.com/en-us/product/accessories/probes/fluke...
Nice job and write-up. As the author says CRTs are dangerous. Even when they're off they can still carry insanely high voltages. The flyback transformer is one of the more dangerous components of them. I'm great at electronics repair and I tend to avoid them. Luckily these days that's easy :) If you don't know what you're doing, you shouldn't attempt it. Just get a more technical friend to do it. If you do know what…
I've always wondered why modern multimeters don't have a "discharge" option. I.e., you select the discharge mode, put the probes on a capacitor, and watch the voltage go down, while an internal current limiter makes sure that it happens at a safe rate.
Nice job and write-up. As the author says CRTs are dangerous. Even when they're off they can still carry insanely high voltages. The flyback transformer is one of the more dangerous components of them. I'm great at electronics repair and I tend to avoid them. Luckily these days that's easy :) If you don't know what you're doing, you shouldn't attempt it. Just get a more technical friend to do it. If you do know what…
I've always wondered why modern multimeters don't have a "discharge" option. I.e., you select the discharge mode, put the probes on a capacitor, and watch the voltage go down, while an internal current limiter makes sure that it happens at a safe rate.
But this only works up to the voltage the multimeter is rated for (i.e. usually 300 or 600 V). If you wanted to make it safe to put 30 kV across the multimeter, it'd have to be designed with sufficient insulation etc. for that.
Hire a professional.
To fix a quarter-century-old monitor that was nothing special when it was new.
Why? I mean, I wouldn't bother fixing the thing anyway, but hiring somebody is going to cost you more than a much better brand new monitor.
I called around to various TV repair shops and was generally told they couldn't do it, or that it'd be prohibitively expensive. Finally, an electronics surplus store in my area referred me to a gentleman of the old-school AV hippy variety who knew how to repair all sorts of old equipment. He was able to construct a tool to ground the machine while working on it and we did the repair successfully together. It was an adventure!
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Even with the externalities accounted for, if you must use a monitor, it might be better to buy a new one than repair the old one. The replacement parts have a footprint, and a newer monitor might use so much less power in operation that it’s more efficient to make and use it than to continue to use the older CRT. I really wish there were an easy way to work out if this was where the ‘efficiency crossover happens in…
It'll depend on your usage pattern and local cost of electricity-- if you're running that device that uses 10W more power 24/7, that works out to 87.6 kWh of additional power usage over the course of a year, or about $15 at the current average cost of electricity in the US ($0.17/kWh as of June 2023). If that's a monitor, you'd have to run it for a pretty long time before your break-even point on purchase cost alone…
Earlier quoted context omitted.
The probes aren’t big enough. That’s why it’s often a big screwdriver and jump lead to earth. The better option is the Fluke 80K 40. https://www.fluke.com/en-us/product/accessories/probes/fluke...
Not big enough in what way? A normal probe should be able to handle the distancing and the small current fine. Maybe it would lack insulation but I wouldn't use the word "big" for level of insulation.
Here's a recent Twitter video showing what happens when you combine a flyback transformer and faulty insulation: https://twitter.com/zh1nu/status/1673487720780529664
(Irrespective of the answer to this, there is no chance at all that I would ever mess with crt circuitry. But I am curious.)