Hello!

It is possible that even though the PIN is not missing, it is still possible that one of the cables is broken. For example, the synchronous PIN cable. You will most likely have to open the monitor casing, even if you are only replacing the VGA cable. If the problem is more serious, you may need a classic TV repairman, which is becoming increasingly rare.
By the way, I found this forum post because I am completely stumped by this monitor modell. There is very little information about it. It is only recommended by industrial parts supply sites mostly in Aviation Industry, so it is very non-consumer information sources, and among the videos of a vintage PC builder influencer. In addition to the rarity of the monitor, it caught my eye because of its extraordinary features. I did not know about such a completely real flat CRT in 1992. Can I ask where this flea market was. in which city / countrey? Although it is unlikely that another one will pop up. It would be nice to hunt it down. If you are not far from me and you do not want to keep it despite its uniqueness, we can somehow talk about a purchase.
Best regards,

Best regards,
György
Hungary

stichas wrote on 2024-10-18, 12:53:

It states that it is a VGA monitor but it is constantly out of sync.

Yeah, I can confirm that the picture looks like the horizontal sync is not working. If this monitor is a fixed frequency VGA monitor, it's quite likely that the capture range of the horizontal oscillator is quite small. Standard VGA is at 31.5kHz, and it's perfectly valid for a VGA monitor to not sync if the frequency is below 31.0kHz or above 32.0kHz. The monitor likely has a control for the basic tuning of the horizontal oscillator (sometimes called "H FREQ" or "H HOLD") inside the monitor, which might be de-tuned. Furthermore, if you open the monitor, you should check continuity from the HSYNC pin (pin 13, the center pin of the bottom row) of the video connector you took the photo of to the HSYNC input of the monitor electronics.

ecchphoto wrote on 2025-05-09, 07:15:

I did not know about such a completely real flat CRT in 1992.

Yes, this is in fact quite special. It's Zenith's proprietary "Flat Tension Mask" (FTM) technology. If you are interested, this name might help to get you started on Google to find more information. While competing shadow mask designs used the dome shape of the mask to stabilize it against thermal expansion which would warp the mask and cause funny colors, Zenith managed to apply that much tension to the mask that it kept being stretched (although with less force) even if it got warm. The pre-tensioning outweighted the thermal expansion of the mask.

I had one of these flat Zeniths back in the day, but not this model. It produced a very pleasant image, but it was also one of my first experiences of a monitor failure. Of course this could be because I bought it used at a computer show, there's no telling how many hours it had when I got it

Difficult to repair due to house part numbers and yes, was high failure rate. Even back in the day, seen 1 or 2 and they were new back then. I was working at university that bought Zenith stuff.

Some of them had that fan to cool the internals.

Cheers,

mkarcher wrote on 2025-05-09, 16:36:

ecchphoto wrote on 2025-05-09, 07:15:

I did not know about such a completely real flat CRT in 1992.

Yes, this is in fact quite special. It's Zenith's proprietary "Flat Tension Mask" (FTM) technology. If you are interested, this name might help to get you started on Google to find more information. While competing shadow mask designs used the dome shape of the mask to stabilize it against thermal expansion which would warp the mask and cause funny colors, Zenith managed to apply that much tension to the mask that it kept being stretched (although with less force) even if it got warm. The pre-tensioning outweighted the thermal expansion of the mask.

Thanks the infos! I already met the FTM technology. I found the article about reveal of that technology, etc.
https://books.google.hu/books/content?id=Frbt … Gf9bjimQ&w=1280