Vynix wrote on 2023-04-29, 11:43:It depends. […]
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It depends.
If by breathing you mean the picture expanding when you show a bright image on the screen (this is generally called blooming) then it isn't fixable in any achievable way, as it stems from the electron guns (or cathodes in Trinitron/Diamondtron tubes) pulling so much power that the high voltage slightly drops, causing the image to expand slightly. Some CRT monitors had a dedicated HV regulator to counter this.
As for the other form of picture breathing, where the picture cyclically expands slightly and shrinks down without any audible ticking sounds (which would indicate a problem with the high voltage arcing somewhere), I unfortunately don't know much about this matter, I've heard that it could be caused by an unstable B+ voltage, but that, I cannot confirm nor infirm if this is the case.
Also HV arcing tends to be more sudden, with a ticking sound as the high voltage arcs to ground, like a sudden snap.
I mean the second form you described, the most commonly described as breathing, the picture's geometry expands and shrinks as the screen brightness changes, like for example switching from one scene or one level to another in a game, with the picture going to black before reappearing again, and inbetween you can clearly see the expanding and shrinking.
It appears to be something very often associated with Trinitron CRTs and Monitors, but like I said before most people just turn down the brightness and they're generally happy with the results, and let it be. While not containing an actual hardware service permanent solution, I found this interesting description in Reddit, it's a bit long but I find it interesting:
"This issue is easily fixed. Details below:
This is called “breathing”, and often incorrectly called “blooming”. It occurs when the cathode ray is losing its “stiffness” due to an excessive drop in ultor anode voltage. The excessive drop in voltage is occurring because the cathode ray current is too high.
Electrons enter the CRT through the cathodes, which emit electrons into the vacuum tube in a cloud known as a cathode ray. The electrons in the cathode ray are accelerated towards the screen by two positively charged anodes: the G2 anode and the ultor anode.
The ultor anode is connected to the phosphor screen, so that the electrons that impact the phosphor do not build up there, as that would cause the screen to become negatively charged, which would end up repelling the cathode ray.
Electrons from the cathode ray exit the CRT through the ultor anode. Gamers often call this the high voltage anode. It has a suction cup connector that is connected to the flyback transformer. At the start of every line of video, the flyback transformer literally pumps the excess electrons out of the CRT, through the suction cup connector.
When the cathode ray current is too high, too many electrons build up in the ultor anode, causing the positive charge of the anode to drop, that is, the voltage drops. When this happens, the electrons in the cathode ray move slower, causing the cathode ray to loose its “stiffness” and it bends too quickly as the line of video is drawn, causing it to expand further to the side than it is supposed to.
The fix for this is simple! You need to decrease the cathode ray current AND increase the stiffness of the cathode ray. First, lower contrast as much as possible until going any lower makes peak white start to look too grey. This decreases cathode ray current, and therefore decreases the amount of excess electrons that can build up at the ultor anode.
You can further decrease the cathode ray current by making the cathode ray thinner. The easiest way to do this is to lower the brightness as low as it can go, so that the picture is almost totally black. Then, to make the picture have the correct brightness, don’t use the brightness setting, but instead increase the G2 “screen” dial on the flyback transformer until the picture has the correct brightness. This makes the cathode ray sharper and thinner, which decreases cathode ray current, AND it does one more thing: it makes the cathode ray more stiff because the G2 setting determines the initial acceleration applied to the electrons".
I tried this at the time and it alleviated the problem to the point where it's perfectly acceptable, but I'd like a future proof solution even if it demands some work/service
