Hi to All,
it's been a long time of experimenting for changing original EL560.400 of COM120B with TFT-LCD, but it was worth it!
Now, let's do it in turn:
I start with HS, VS, Clock and Data lines present at the connector J1 /Sheet 5 Video CNTR/.
First problem was that EL560.400 have 560x400 pixels, and TFTLCD with 4:3 format have 640x480 pixels.
So, I need some double port RAM with controller, and I found SSD1963 as appropriate IC to drive TFTLCD.
Second, I found out that Video CNTR of COM120B send 624 pixels/line /560 Video + 56 garbage /before video/ +
8 pixels Horizontal Sync /active 0/. 56 pixels Delay of HS solve that, with help of uController and some logic ICs.
Next, another problem. In modes, like Oscilloscope and Analyzer, also in text modes, where are also graphics
/Oscilloscope, analyzer, and bars showing parameters /Voltage, SINAD, Power, etc./ designer at IFR made a remarcable trick:
That is, he want to make grid and bars less brighter then rest of frame, and he solve that with sequentally switch
on and off pixels of, say grid in analyzer mode or other fields of interest, and that sequence walk p-frames on, then q-frames off,
and again, and again...
It seems like PWM, and thanks of persistence of phosphor, which is base of EL display, that persistence acts as a Low-pass filter,
and everithing is great for EL display.
Well at TFT-LCD there is different situation. TFT-LCD has minimum persistence /it is fast!/, and our eyes see grid blinked
at high rate, of course, but seen. After 5-10 minutes, eyes got tired.
At Sheet 11 Video CNTR, designer wrote EL Flat panel Display, 560x400, 4 Shades. And at Sheet 5, one would see that
"responsable" for that is U17 and /maybe/ U4.
So, I check signals that are inputs for U17 /named Red, Green, Blue and INT/. INT is of no interest at that moment.
RED signal containing good part of the frame - text, trace, bars without grid.
GREEN signal containing trace and bars.
BLUE signal containing grid.
So, I connect that signals as inputs to my design, and, voila! I am a lucky person!https://drive.google.com/file/d/1YX_sl1 ... sp=sharing
Now, I still have a job to make design fine /I think Red is not goos for the text, better Amber, and grid must be more lite/.
Making PCB and some mechanical jobs to make replacement of display easy.
If it is interested to that community, I will post /as finished/ Schematics, PCB, and mods of Video CNTR Board.