Nav screen dim because of mk4 unit
 

Just replaced the mk4 nav unit with another, and the screen has become dim. Its like its faded, and sort of the contrast white balance has changed, as its hard to see the writing in some angles.

Its definately not the screen, as when i put another unit in, the screen is back to normal. Any suggestions anyone? Tried downgrade and upgrade already. Also tried a different drive, but i doubt that has anything to do with it.
I really didnt think the mk4 unit had much to say to screen regarding brightness/contrast/white balance.

Did you try going to the 'settings' and adjust the brightness? Might just be preset from the MK4 ???

Yeap, tried all that.

I've only ever seen this when the mk4 has a memory fault mate (you may find that it wont save the brightness setting either).

The way that the TV, mk4 and screen interact is a bit of a mystery, AFAIK it's,

The Mk4 is used as the primary display driver device and the screen uses the defaults of that unit (or custom setting of that unit (see the nav service menu)).

The TV is the secondary display device, and will only take over if the nav drive goes off line, once off line the TV acts as if it's primary, not sure if the TV has any user setting TBH.

The screen is just a dumb terminal, and has no user settings, so is controlled by the nav unit or TV module, there are some pots on the LCD controller panel (behind the LCD), that you can use to adjust things like contrast, brightness, Green, blue and red adjust as well as scroll settings, but this requires a LCD strip down (I've done it to repair a scrolling screen), its a bit tricky as you need to fiddle with each pot till you find the right one (while its working).

Its definately not the screen, as changing the mk4 with another one, fixes the problem. It happened when I thought it would be a good ideas to brush off the dust on the circuit board!

I did notice something yesterday, when I lowered the brightness to the lowest setting, it didn't make a difference, until the unit rebooted and it had made the screen so dark, I could just about find the settings to brighten it back up.

I have changed the lcd quite a few times, but never noticed any adjustments behind it, will look out for that. Don't think it will make a difference to this situation though :(

Indeed, it does sound like the mk4 mate.

Also check the brightness setting the the service menu mate.

The pots are behind the circuit panel mate, so the you need the lcd off and then you need to lift the circuit panel off the housing and they are on the back side.

Only if you leave the screen mated to that mk4.

Service menu, which one are you referring to, the one where you press info, as you turn ignition on?

Will also try the lcd method, as I do need to replace a screen, on one of my units.

press menu select set (or settings) then hold the menu button for 10 secs.

What do you mean "brush the dust off the curcuit board"? These are usually spotless inside.

What sort of dust (colour, appearance)?

What sort of brush did you use (synthetic, horse hair)?

Sounds to me like you either
- zapped the unit with ESD using a synthetic brush or
- there was water damaged in the unit and by abrasive means some connections went open.