September 21, 2019, 12:53:18 am

MegaPixel LCD

Started by barcher174, December 27, 2014, 01:45:47 am

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pentium

Progress: slow.
I got dragged into helping someone buy two cars so I had to write most of the last two weeks off. When I did have the time I noticed that yes, the inverter and the A/D board do not both use 5v. The A/D uses 5v while it seems the inverter side wants 7v so that 2V difference is probably making the inverter upset. I gotta varify that is the voltage is correct but if the load is light enough I can just add a 7807 with a heatsink and we should be good.

-NeXT 68040 Cube with NS 3.3 and 64Mb ram

gtnicol

I've often thought of trying to find an LCD panel to replace the tube in the standard NeXT monitors. That might be another fund project.

nextchef

Quote from: "gtnicol"I've often thought of trying to find an LCD panel to replace the tube in the standard NeXT monitors. That might be another fund project.


Add a intel NUC or other small pc inside and run previous or another emulator on it to create something like the original iMac.

pentium

Further research found that yes you were right and the inverter wants 12v and the A/D board wants 5v. Okay that is something I can more easily work with because then the inverter ties in before the regulator and the A/D after. Once all but the video signal line was soldered in the inside looks like this:



The next issue was that I had lost inverter control. When the screen went to sleep the backlight remained on and the brightness controls no longer responded. Investigation found that NEC had crossed the wiring and on the way between boards a grey wire became a brown wire and vice versa. Swapping them around made the screen entirely functional. Once I confirm the screen doesn't do anything funny running on the bench I'll tack down the video line that will cause all three color signals to be tied together and plug it into a piece of black hardware.



I know that RCA jack is the microphone but does anyone know where the speaker plugs in?

-NeXT 68040 Cube with NS 3.3 and 64Mb ram

barcher174

The speaker hooks into the 2 pin header next to the MIC jack.

pentium

Should of guessed. Both traces from the header go into a nearby TDA7052 mono amplifier. Now to source a small but loud enough speaker to put inside.

-NeXT 68040 Cube with NS 3.3 and 64Mb ram

barcher174

I've found these to work pretty well:

https://www.amazon.com/gp/product/B00H8VXQ8M/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

They are thin and have an adhesive strip for easy mounting. I also use them in my modified sound boxes.

pentium

Should of expected it. While the monitor is displaying an image because the monitor SUPPOSEDLY can't do up to 1280x1024 the image is stuck partially off the screen and all the controls are locked out so manual geometry adjustment is not possible.




That being said we ARE at least getting an iamge and it's powering itself directly off a piece of black hardware. :D

So a 17" monitor is likely your minimum as it seems the majority of 15" displays max out at 1024z768 and end up doing the above when fed video.

-NeXT 68040 Cube with NS 3.3 and 64Mb ram

barcher174

I wonder if you could buy a new controller for the LCD? Although it could be cheaper just to get a different monitor.

pentium

It's going to be cheaper to get another NEC monitor. A 17" model should work however then being the weird perfectionist I am, I need to track down the right frame. Nothing with rounded edges. Flat surfaces. Square.
A Multisync 1760nx should work. It is designed to handle 1280x1024 @75hz.



Also, I am now aware that the brightness keys on a piece of black hardware actually fiddle with the signal intensity. It was never the computer fiddling with the brightness circuit within the monitor.

-NeXT 68040 Cube with NS 3.3 and 64Mb ram

barcher174

Yeah, I guess I never mentioned that. The brightness controls work with mine as well.