Sega Nomad RGB to VGA TFT LCD Mod...

Here's the display:
http://www.good-display.com/products_detail/&productId=277.html

I wired directly from the Sony CXA1645 to the LCD Board, but the screen says 'No Sync'
I've built a sync separator using the LM1881 chip with no positive results.

Here's my question - I'm thinking the VGA monitor simply doesn't accept a 15khz signal from the Nomad?
I'm planning on testing the board later today with my Dreamcast VGA box.

I'm still a novice at some of this, so I'm not sure which way to go next.
Anyone have suggestions / questions?

 

Well vga is 31khz

The screen does seem to accept cvbs (composite) so you could just that initially to test. It might not even look that bad on a tiny screen.

What's the part number of the main ic on the pcb? Maybe it's possible to switch it into 15khz rgb mode by changing a jumper (or lifting a pin). Post part number and can see if there's a a datasheet.

 

Here's you go: MST703-LF / A6MJA8ZB / 1246F
I found the datasheet as well: http://www.datasheet4u.com/datasheet/M/S/T/MST703_Master.pdf.html

Composite input looks pretty clean on this screen - hoping for RGB quality of course.
Let me know if anything stands out to you in the datasheet.

 

Where did you wire up csync?

 

Layout and background info:
I ran composite from the Nomad to pin 2 on the LM1881 and hsync / vsync separately out to the pins on the VGA board.
References:
http://www.mmmonkey.co.uk/composite-sync-stripper-lm1881/
http://www.gamesx.com/misctech/lm1881.htm
Pins 2 & 7 have a .1uf resistor between them. Pins 4 & 6 have a 680k ohm / .1uf resistors between them.

I took the same LM1881 and put it in a NUS-CPU-04 N64 for csync and the circuit is working fine with hsync out.

 

Followup: Got around to setting up the Dreamcast today and the VGA screen doesn't display an image with it either.
I saw it display 'Out Of Range' for a split second, so I'm under the impression that I'm dealing with a 15khz / 31khz issue.
Now I just have to see if the board can be altered to force it to go into 15khz mode...

 

Dreamcast outputs 31khz if it's in vga mode.

 

Further testing and results: No signal from the Dreamcast with a Naki VGA Box, which should have produced a picture at 31khz.
Hooked the MST703 board to an older HP netbook and I was able to get a signal at 640x480 at 60hz. 800x600 at 60hz was unreadable (see last photo in set).

I think the photos I've attached show enough about the screen resolution and detail level to know that the screen just may not look as great as I hoped it would.
The sonic footage is just me playing a youtube video (of RGB output to a framemeister), not actual gameplay.


It is likely that I won't be pursuing this mod any further as the results will be so close to a composite signal, that it won't be worth bothering with. Perhaps it'll look slightly better at 31khz, but I seriously doubt it.

 

Nice i need a lcd for my nomad. But want rgb lcd like the replacement game gear one.

 

I'm interested in this also, every replacement screen I've ever come across for the Nomad only accepts composite video, and as we all know, that looks like crap. Would be nice to find one with a controller board that accepts RGBs.

 

necro bump.

https://translate.google.com/transl...s://www.kadenken.com/shopdetail/000000000499/

enjoy!

 

Quite serendipitously (yes, it's not a real word), I came across that board earlier today and think I'll get hold of one to try out.