I have a Fatshark transformer which is a screen with a build in 5.8ghz video receiver and I want to change the receiver in it.
I know where to weld my voltage and ground wires but I just don't know where to connect my video signal wire.
If you look at the picture below, I'm sure it's one of the 9 pins in the red circle, since these are the only pins that connect the receiver to the screen.

Here is what I know about each pin : (starting from the left, see picture below)
1 : No voltage
2 : 2.8V when there is no signal coming. 0V when receiving a video signal from my drone.
3 : 3.2V
4 : No voltage
5 : 4.78V
6 : 0.66V when there is no signal coming. 2V when receiving a video signal from my drone.
7 : Something between 0.5V and 1V that drop down close to 0V as I hold the multimeter on it using pin 1 or 4 as a ground.
8 : 1.1V
9 : 0.4V when there is no signal coming. 0.1V when receiving a video signal from my drone.

How can I identify the video signal pin ?

Notes :
- Among the pins there is probably an audio signal, but my drone isn't equiped with a micro. There could be an RSSI signal too.
- I searched for diagram about SM1259R, but couldn't find that anywhere.
- I contacted Fatshark, but they couldn't answer my question.

 

You're better to search for the datasheets for the chips used to see what they do, then you start to meddle...

 

Hello, I found myself having the same issue as the one described on this post and I found the video pin in case anybody is wondering.

This is the board used in the Fatshark Transformer FPV goggles, I came into this need as for some reason, the AV-output port on my particular goggles were not working.

The board my model has is the SM1259R (V1.2) and this is the pinout I came up with starting from the left on the screenshot bellow:

1 : GND
2 : Not tested
3 : Not tested
4 : GND
5 : 4.78V
6 : Not tested
7 : Not tested
8 : Video pin
9 : Not tested

I hope that this reply helps more people figure this out!