VOGONS


First post, by anetanel

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Hey guys.

I got a NEC JB-902ME-5 green monochrome monitor, with composite input. It turns on and the picture is quite bright, but it does not seem to "sync".
I hooked it to several outputs, including the Atari 800XL in the picture, but although I can see that the signal is getting through, the display is always fuzzy. I played with all the knobs and switches in the front and back, but nothing I did fixed the issue.
What could be the possible reason?

Also, I was not able to find any mention to this specific monitor on google...

Thanks 😀

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Reply 1 of 6, by 133MHz

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Which knobs are on the back? It looks like the horizontal oscillator frequency is off, requiring adjustment of the H.HOLD or H.FREQ control.

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Reply 3 of 6, by ATauenis

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Does something changing on H Hold knob adjusting? Also HIGH/75 Ohm switch might be useful, did you tried it? For devices with TV out the normal mode is 75 Ohm, not High (1k Ohm).

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Reply 4 of 6, by anetanel

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Well, apparently I was simply too gentle.
The H Hold knob gave some resistance so I thought it was turned all the way. Apparently it wasn't!
Gave it (fearfully..) some extra turns and the picture stabilized!
After a year and a half from testing this monitor for the first time, it finally came back to life 😀

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Reply 5 of 6, by 133MHz

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Nice! Glad you got it working, love these tiny green monitors 😀
On many of these 'TV-type' monochrome displays the horizontal hold control is actually a variable inductor (instead of a potentiometer) where a ferrite core is being slid in and out of a coil, hence the knob can be turned many times without hitting a mechanical stop.

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Reply 6 of 6, by anetanel

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The next step is to find some way to hook it up to my AT clone PC.
I got there a card with MDA output, and as far as I know the signals arn't compatible.
I was able to get both PAL and NTSC work on this display, so I figured I may try to hunt for a CGA card with composite output.