RGB csync waveforms don't correspond to what is displayed ??

[bigboss59]

Hello,

I might have an apparently damaged control board which drive a LCD assembly (attachment)
The LCD assembly is working alone with power and a composite NTSC signal.
This motherboard can't be buy anywhere or a whole used unit must be buy... (cost 3K as it's very rare)
I don't have any information on the control board.

(The board can send RGB with csync AND composite at the same time (superimpose))

I'm focussing on the RGB output

So I'm trying to check the RGB with Csync signal; it should be 480i from what I understand in the datasheet.

So I made a scart cable like this :
https://en.wikipedia.org/wiki/SCART
- pin 20 and 17 for Csync
- pin 5,7,9,11,13,15 for RGB
- pin 8 at 12V
- pin 16 at 1.8V (resistor divider using 12V and RGB grounds)
I didn't take the terminaison of 75ohms into account !
Problem SOLVED


I connect it to a scart TV that support 480i and I got a full white screen however according to the waveforms I don't think that's correct ?
If a full white picture was send I should have all channels to 0.7V during 50uS, right ?
Timing seems to be correct according to the datasheet.
The measurment was done when connecting to the TV

Don't hesitated to ask any details or give me some hints/advice.

Best regards