How picky are CRTs about the 'cleanliness' of the mains power?

Cleanliness referring to electrical noise from thing like ac motors in fridges, powerline ethernet, etc. Cleanliness is also referring to the squareness or 'sine-ess' of the ac waveform, when powering from UPSs.

Pickiness refers to the CRT (my case being a 1985 JVC TV set) acting abnormally in anyway, from minor picture/sound distortions to hardware damage (lowered power efficiency by itself isn't abnormal behavior for the purpose of this question), as a result of say, a square mains wave (from a UPS).

So are CRTs fine with the dirty power most home UPSs provide?

  • "(my case being a 1985 JVC TV set)" - so really you only care about whether your set is picky, right? Why would you be running it from a UPS? Have you tried it? May 19, 2020 at 9:15

1 Answer 1


That question is a bit broad. what parts of 'pickyness' are meant?

One needs to distinguish between the CRT as main powered device and the signal path. Also, if CRT sould refer to 'just' CRT or TV sets. Also, it depends quite alot on the technology used, as CRTs came in countless technological variations. From 12V DC feed all the way to 400 Hz AC.

As a device powert by mains voltage and frequency, they are rather robust. Well, or as robust as their power supply is. With old, transformer and rectifier based devices efficiency depends quite on a good sine, but they can as well cope with many distortions - back in the days, power was often only sine by name :)) On the other hand, more modern CRT with switching PS don't care much.

Now, the signal path is a different part, as it's here mainly about shielding and crosstalk. So again quite installation and model defined. Any signal powerful enough - and vacuumer motors can be quite strong sources - will interfere with the signal displayed. More so when using a TV and a modulated transmission.

Whatever the reason for your question is, a better answer will need more detailed information about device and setting.

  • I've edited the question, so take another look? I kept it vague on purpose, so the answer would be in general terms anyone reading the question could use for their situation. May 19, 2020 at 2:20
  • @AlexanderM CRT's have been used or over 80 years in almost countless variatios of electronics and principles - the only common thing is that some kind of tube is used to show the picture - as that's what the term says. Already the difference between TV and monitor is enormous. There are dozends of books with hundrets of pages explaining issues with TVs allone, Impossible to put that in a single question or answer. Drop the vagueness and ask detailed and exactly what your environmet and issue is. The only way to get a useful answer - for you and others.
    – Raffzahn
    May 19, 2020 at 3:05
  • 2
    No idea about square-wave UPS supplies, but back in the day I had a monochrome CRT monitor that had a rubbish display quality running at "high resolution" (i.e. 80 x 25 text!) It turned out the problem was the mains power supply. Some previous owner of my house had installed an extra power socket simply by drilling a hole through an internal wall and wiring it back-to-back with an existing socket, using a bit of poor quality cable and crappy electrical joints. Running it from a properly wired socket fixed the problem.
    – alephzero
    May 19, 2020 at 4:05

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