LCD operation / general polariser question

[MegatronUK]

I think I've succeeded in powering on a widescreen panel from a Pioneer sat nav system I own, minus the head unit and with the aid of an engineering manual. It's been a bit difficult becuase not all the voltages are marked on the engineering diagram and it's awkward to operate the lcd seperate from the head unit (lots of flat ribbon cables):

The backlight powers up when I connect +12v and ground to what I've figured out is the correct locations on the control board:


I think I've also got the correct locations for the +5v and ground lines for the general video circuitry and logic, because when I connect them up the screen immediately goes black (not the light grey colour of a lcd panel with no power to it):


Am I correct to assume that the LCD encoder on the board must be working correctly in order to activate the polariser in the panel?

[MegatronUK]

Can anyone help me with the following diagram?



I'm trying to get an RGB+CSync signal to display, but nothing appears on the screen - it just stays black. The input signals are connected to ANR, ANG, ANB and CVIDEO (it's labelled CVIDEO on the pcb, but CSYNC on the diagram) - at the moment I have nothing connected to the RGBSEL line, and it currently showing a reading of +5v.

Can someone with a little electronics knowledge tell me whether RGBSEL should be low or high in order to select the analogue RGB inputs?

[Mario]

Try both. It can't hurt, right? And try putting composite into CVIDEO, see if that works. Have you looked up datasheets for any of the video chips?

[Basement_Modder]

I'm not sure I understand the question.

[marshallh]

You will probably have to do some trickery with the angle/tilt sensor spots, the screen is probably set up so that it shuts off once it's closed. The next step is to study the original wiring and found out what switches are pressed when it's held open.

[MegatronUK]

Thanks. I'll have a look at that today and also see if there's any reference in the engineering manual about what the title and angle sensors should be when open.

[MegatronUK]

I've looked all over the control board for the lcd and searched the eletrical diagrams in the manual, but I can't find any link between the angle/open-close sensors and the inputs to the lcd control board.

What's weird is that there seems to be power to all of the ic's, the regulators are showing the four voltages they're supposed to: +5v, +12v, +18v and -15v, and even the traces after the lcd encoder show the r,g,b lines are at various levels - so it's got to be running.
I've also realised that when I hook up the +5v the backlight is actually switching off, not being polarised like I previously thought.

I'll probably not spend much more time on this as I don't seem to be getting any further forward. I just wonder if the headunit uses the I2C bus to start up the lcd encoder or something.

[MegatronUK]

There's got to be some sort more logic that needs to be bypassed to get an image to display - I've figured out that if I apply +5v to the 'DIM' solder pad (dimmer line to the DC-AC convetor for the CCFL) the backlight comes on, without +5v applied that line is only around +0.3v, and I'm guessing its that which switches the backlight off when +5v is applied to the controller board and all the ic's spring into life (without any ic's, the +12v to the DC-AC convertor powers the backlight on without any problems).

So, backlight on when the logic is running. Still no picture being shown though.

More work to do.