I took apart the OBD (the in-dash LCD display) the other night to see if I could restore some lost pixels and thought I'd share some info that may be helpful for those of you DIY types out there.
When I ran the pixel test I noticed that there were no single pixel faults, but that there were entire columns of pixels out. The pixels that were lit were of fairly uniform brightness, and by touching the display lightly I could "turn on" the stuck columns, so I was encouraged.
I took the unit out according to the directions posted in the archives, and found that I had a Borg display. After getting the back off of the unit I found a pretty clean interior, with none of the dust problems that the other OEM design apparently has. I was hoping to see an obvious problem such as a loose connector, but no luck there. After poking around a bit I noticed that the main printed circuit board (PCB) was pretty "clean" (from a workmanship point of view), but that the solder joints at the connection of the flat cable to the PCB were badly corroded. Clearly the OEM used an acid core solder to assemble the cable to the PCB. Acid core solders are great timesavers when you have to solder to a surface that you don't want to take the time to clean properly, but over time (years) the remaining acid reacts with moisture in the air and destroys the joint. That had happenend here, and the corrosion was obvious.
The correct way to cure the problem is to disconnect the cable from the PCB, remove as much solder as you can with a wick, and then do a thorough cleaning of both the cable and the PCB. Most people don't have the equipment to do this, and those of you who do know what to do next. For those of you who don't have the equipment or patience to do a cleaning, simply re-solder the connection with a standard rosin core solder. This will restore the connection and should last many years. This process applies to both ends of the cable (the PCB end and the display end). I was missing about 30% of my pixels before, and re-soldering these connections restored all of them.
PS Just so you know, these displays are not active electroluminescent, but simpler (and less expensive) backlit LCD. The displays themselves therefore cannot "burn out" as some seem to think. All the power for the lighting of the display goes into the backlight incandescent bulbs, and the pixels simply act as addressable shutters for this light. Also, if for some reason you would prefer a white-on-black display, you can remove the color gel from between the bulbs and the display.
The cable shown in this photograph, is the cable which connects the front panel switches to the main PCB. Unless you are having a problem with switch response I would leave that cable alone. There is a similar flat ribbon cable which runs between the display PCB and the main PCB, and that's the one I was was referring to in my post. On my OBD, the solder joints at the cable/display PCB interface were done by machine and were in good shape. The solder joints at the other end of the cable, at the cable/main PCB interface, were hand-soldered and those were the ones I re-did.
BTW - in the Borg unit there are no "contacts" to clean. Everything is soldered in place. It's just that the soldering was badly done.
Scott
