Highline Mk3 display corrupted - with pictures

[jpdoc]

Having just successfully renovated the solenoid on my beloved connie 2.5 (with the much appreciated help of some of our fellow members) I thought I'd try and deal with my sat nav problems. I posted some months ago about the display on the mk3 getting dimmer and dimmer but hadn't really got much further when the solenoid packed in.

A bit of history - this is about the 4th sat nav disc unit I've had, the first being a mk2 (the car is 1999) and the rest being mk3. They all needed some renovation from the dreaded water damage (I've spent eons tracing leaks in the boot and it still gets a bit wet) and though they ran for some time they all eventually succumbed to the "red light stays on" power issue. When this happened I would pull the cd unit and run with the blocky simpler display you get without it (and no sat nav, of course). Up until now with the CD unit out the simpler graphics display returned to its normal brightness and was clean.

The current mk3 unit was working, albeit dim, but had a CD stuck in it. After fixing the solenoid and getting the car drivable again I got the CD out and reinistalled the drive. When I fired it up the screen, while still dim, was corrupted with various flickering horizontal lines (see pic).

As an aside, I have at various times tried to get into the service mode detailed here -

https://the75andztclub.co.uk/forum/s...hlight=service

but have never managed to get service mode to come up. Reeb's instructions say to select "set" on the menu screen, then press the left hand rotary button to access the set menu, then press and hold the button marked menu for 10 seconds. Problem is when I press "menu" it just goes back to the menu, as you'd expect. I've held the menu button down for ages with no change. So turning up brightness in the service menu was not an option.

So I pulled the unit (after letting the red light go off) and looked into getting another working one. Much to my surprise, however, I found that even with the unit pulled the simpler blocky graphics were now also corrupted with horizontal lines, and were now very dim as well.

I checked the video tuner module and it was dry with no obvious signs of water damage. I reseated all of the video modules connections. I disconnected the battery for a while. Still a corrupted dim display.

Just to be sure I reinstalled the CD unit. Still horizontal lines of corruption (albeit not quite so bad) and dim display. Uninstalled it, still dim and corrupt.

So I'm now very confused. Can anyone out there with experience with these units explain any of this? I'm not keen on splashing out for a new CD unit only to find that the display is still messed up because the problem is elsewhere.

And where could the problem be? I'm assuming the video tuner itself, but could it be the actual screen? I've previously assumed that the screen was ok because when I took out the CD unit it went back to normal brightness, but for no apparent reason this is no longer the case.

The attached images are - first pic is with the CD unit removed, next three with it installed. I've bumped up the brightness and contrast on the jpg files a bit so that the corruption would be move visible but all the screens are pretty dim.

All suggestions gratefully appreciated.