First post, by Tronix
Hello, i have old terminal board (just a board and nothing else):
BULL S.A CARTE LA2.1 290 108-00A NEP-14T
I replace broken LED1 and LED2, traced the main power circuits and made a pinout of the blue connector J4:
So, I connect +5 and +12 to ATX power supply. Then i attach HSYNC, VSYNC and color components to MCE2VGA video coverter and started the board, it shows signs of life, but both LEDs are blinking and nothing is shown on the screen (gray rectangle). Once I touched something on the board and I managed to see an error message on the screen (Err. 4). I could not repeat this again for photo.
SCN2674BC4N40 CRT controller pin 16 /CCLK:
8088 pin 19 CLK:
I do not quite understand the purpose of the J7 (W1, W2, W3, W4) jumper block - he distributes the main clocks from crystal generators to both ASIC NEC logics ... Depending on some of its positions, the frequency of the HSYNC changes, maybe something else...
And W5 jumper around BOOT EPROM - without this jumper board does not init CRT controller, does't start blinking LED.
I dumped all *PROM from this board, they are all in the attached file.
So, any info wanted...