Project Help: CRT 4:3 circles photo gallery

I’m working on a write up about aspect ratios on newer square pixel displays and calling out to the community for help on one element I can’t do on my own. Putting together a gallery of photos of as many CRTs as possible displaying some ratio patterns in the 240p test suite. If interested and willing to contribute read the instructions below (and a massive thank you!)

If under the impression that your crummy CRT can’t possibly be useful here that couldn’t be further from the truth! Whether it is a cheap kmart special you’ve had for years or a fancy professional monitor everything helps. A range of CRTs will build a fuller gallery of what these displays actually looked like. If you are willing to help but don’t have a flashcart let me know and we can work out an alternate sample (ex. the moon from Chrono Trigger)

What you’ll need

  1. CRT
  2. Decent quality camera (if all you have is a phone camera that works!)
  3. One of the following consoles: NES, SNES, Genesis/MD, TG16/PCE
  4. Flashcart, or other nefarious means to load the test suite rom, for said console

Instructions
Load up the 240p test suite (links for all of those consoles available there) and choose Test Patterns > Linearity. Hitting the ‘A’ or equivalent button should bring up a grid. They look like this. I’ll need a photo of both patterns.

If you have a tripod set it up straight-on, with as little angle as possible, and as close as possible while also getting the full frame of the television visible so that any potential cropping or bordering due to overscan is fully visible. Ideally getting some of the bezel on all sides of the screen. Otherwise do your best freehanding it.

Something like this…

As opposed to this…

Post the photos in as high resolution as possible with the following information to help categorize it.

  1. Console used and region (NTSC/PAL)
  2. Region of the CRT (NTSC/PAL)
  3. Connection method: composite, component, SCART, etc…
  4. Size of the screen, manufacturer, and model
  5. Describe any special adjustments made such as adjusting for overscan, or any other considerations you feel may be applicable about your CRT.

And a massive amount of appreciation for anyone who contributes.

  1. NTSC SNES (1CHIP)
  2. All CRTs are North American pro monitors capable of both NTSC and PAL.
  3. Scart RGB (with Composite Sync) from SNES to Extron Crosspoint matrix switch to pro monitors. One exception: A13SU (4C) has a converter box between the switch and monitor to change the RGB signal to S-Video.

4A. JVC TM-H150CG (15")


4B. Sony BVM-20F1U (20")


4C. JVC TM-A13SU (13")


4D. JVC DT-V1710CG (17")


  1. I did some minor adjusting of the linearity and position of the pattern on each monitor. The A13SU monitor (4C) only has a horizontal position setting in the service menu; no vertical position or horizontal/vertical size settings as far as I’m aware. This is the reason for the corner circles cut off at top and bottom. It likely has pots on the inside for manual adjustments.
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The TV is a Brandt 55170 RH, its chassis is a Thomson TX807.
21 inches SECAM TV (can take both 50 and 60Hz syncs)

240p test suite on a Megadrive at 60Hz, RGB through Scart.

320x224

256x224

That’s with the screen calibrated to show the correct geometry. Because I can’t calibrate the horizontal amplitude on this TV, it means it leaves parts of the active area outside of it and hides important information on some machines (notably the CGA computer). So I set the screen with a little less vertical amplitude to get everything to show for a slightly crushed, but frankly not noticeable, picture.

320x224, then 256x224.

The upper left corner is a bit lower than the rest. It has been like that for years, I’ve never noticed before using patterns to calibrate the screen. I don’t know how to fix it, sadly.

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Very nice @khaz and @Mega thanks for the help!!