Main > Monitor/Video Forum
CRT (Makvision) image is a large bluish blob. Dead, or repairable?
Zebidee:
--- Quote from: jennifer on February 28, 2021, 01:31:56 pm ---Before you write that check you may want to consider a few things...The sockets are just as important as the machine you choose, without them it is useless, Most common for arcade tubes is it CR23 (difficult to find and spendy) best to spend more out of the gate with sockets (Imo). The Beltron (If you find one) doesn't get such a luxury, and at best you have to pin it with a universal...I have had many machines over the years and really like that BK for value/support. Beltron, with little support, Is probibally a better machine since it uses amps over voltage...as a result I have 5 of them, and one of those is even converted over to the CR sockets (project from hell)...Moral of this story is, A cheap bargain isn't really the goal when looking at rejuvenators since it becomes such a critical piece of equipment on your workbench if you mess around with tubes.
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Exactly what I've been thinking (or wanting to think, if that makes sense) for long time. Leading with the CR sockets issue :cheers:
Baldbull:
Success! Replaced the transistor I broke, powered up.. everything looks good.
Something minor I just noticed.. is that for the first minute or two, I get retrace lines at the top of the screen... they go completely away.
It is in the basement.. fairly cold, 55 degrees. is this a temperature issue, or something I should be concerned with?
Zebidee:
It is pretty normal for a CRT to take up to 15 minutes to properly warm up.
While you're in there, might be worth checking your electrolytic capacitors (the aluminium cans) if you haven't already done so. They get old over time. Visually inspect carefully, replace any that look like they are bulging or leaking, but be aware they can fail with nothing obvious to see.
Ideally you'd have an ESR meter to check electrolytic cap health in-circuit (no need to remove capacitor from PCB to test). This is what I'd recommend as you don't have to replace good caps needlessly and you can check cap health whenever you want. However, not everyone has an ESR meter. If the caps are all looking quite old and tired you might just order a "cap kit" for your monitor and replace the whole lot.
Baldbull:
--- Quote from: Zebidee on March 07, 2021, 07:06:36 pm ---It is pretty normal for a CRT to take up to 15 minutes to properly warm up.
While you're in there, might be worth checking your electrolytic capacitors (the aluminium cans) if you haven't already done so. They get old over time. Visually inspect carefully, replace any that look like they are bulging or leaking, but be aware they can fail with nothing obvious to see.
Ideally you'd have an ESR meter to check electrolytic cap health in-circuit (no need to remove capacitor from PCB to test). This is what I'd recommend as you don't have to replace good caps needlessly and you can check cap health whenever you want. However, not everyone has an ESR meter. If the caps are all looking quite old and tired you might just order a "cap kit" for your monitor and replace the whole lot.
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On the component-level, everything looks really good.
I do have a question... and I'm not sure if it is an easy one to answer, but I'm curious what contributes most to the longevity or lack thereof, of a CRT?
In its past life, it was "used" a few hours a day... but powered on all of the time, so.. 80-90% of the time it had no input signal... it just had the OSD "DISCONNECT" box bouncing around the screen with a black background.
Currently, it is powered OFF all but several hours a week, when it is used... so no idle powered time, it is either in use, or powered off. Wondering what is "best practice"?
Zebidee:
--- Quote from: Baldbull on March 09, 2021, 06:02:04 pm ---I do have a question... and I'm not sure if it is an easy one to answer, but I'm curious what contributes most to the longevity or lack thereof, of a CRT?
In its past life, it was "used" a few hours a day... but powered on all of the time, so.. 80-90% of the time it had no input signal... it just had the OSD "DISCONNECT" box bouncing around the screen with a black background.
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... I know of no good reason to do this.
I have a second hand Acer LCD monitor with a yellowish patch burnt-in to the middle of the display because previous owner left it turned on all the time, and by default it shows this "ACER" bobbling around in the middle of the screen. Yep, burnt-in LCD monitor, from default pic on screen, just in case you were wondering if that were possible.
Much easier to get burn-in with a CRT. Once there, impossible to fix.
--- Quote ---Currently, it is powered OFF all but several hours a week, when it is used... so no idle powered time, it is either in use, or powered off. Wondering what is "best practice"?
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Turn it on when you want to use it, turn it off when done :dunno