BMW KE 83ZBM Radio backlight repair

BMW KE 83ZBM Radio backlight repair -by www.bimmernav.com

This brief document describes the process that I took to fix the radio backlighting. Follow this process at your own risk, as my methods may not be the best or correct. BUT I will say it worked like a charm for me.

I used Radio Shack #7219 Micro Lamps 12V 60mA Part number 272-1092C $1.29 for 2 You need 3 bulbs total. Keep in mind, I measured 8 volts on the radio lights, although installed 12 volt bulbs. Keep this in mind, as my method could screw things up in your radio. It worked perfect for me, but keep this in mind when getting your parts.

First Step is to remove your Radio

I used a flat head screwdriver to open the side covers and 2mm allen key to turn the star screws that hold the radio in place.

Then remove the one screw on the top of the radio and carefully pry the top cover off to gain access to the PCBs.

The next step was to remove the faceplate. Firstly remove the volume button, then the two screws on either side of the faceplate. The faceplate will be attached to the very bottom PCB so just let it rest on your work bench. Do not pull it out

Next step is to remove the four phillips head screws that hold the tape mechanism to the bottom PCB. The tape mechanism is connected to the bottom PCB via a connector on the right side (see where wires run up on right... above picture). Pull straight up to disconnect connector. You should not have to use too much force. Notice that the rear left screw hole for the tape mechanism is mounted under the bottom PCB mount. Not sure why, but I put it back the same way.

Next lift the tape mechanism up and out. This requires some finesse as it is a tight fit. Under the tape mechanism is the ribbon connector for the front panel. disconnect the front panel and remove. You can put the tape mechanism back in, but don't screw it down, yet! If you have problems getting this completely out, try taking it out just far enough to disconnect the front panel ribbon connector and remove the LCD PCB first. With this out the tape mechanism comes out very easy.

Once the front panel is off, you need to remove the LCD PCB. There is only one screw that was covered up by the front panel. Remove this screw and pull upwards to disconnect the LCD PCB from the bottom PCB.

LCD PCB removed!

Here is the LCD PCB rear side. Mine looks like crap. OK, first thing is to remove the LCD from the LCD PCB. Take note of which way is up on the LCD. I would recommend using a sharpie pen to write "up" on the top side. Putting the LCD in upside down fits, but you have to do the whole process again unless you like standing on your head to drive.

There are 4 feet that hold the LCD down. Each of the feet have arrows next to them indicating the method to turn in order to affix them to the PCB. With a soldering iron, remove the solder from each of these feet. Then once ALL of the solder is gone, straighten the feet out so that they can be pushed thru the holes. I used needle nose pliers to straighten them out and then carefully pushed the feet thru the holes. You can also put a small screwdriver on the other side and pry the LCD out, by placing it directly next to where the feet come thru the PCB but you MUST be VERY careful or you will toast the LCD

Once removed you see the lights. Like the OBC, these lights are in series. Once one goes out the others will not function. Take note of how the lights are mounted around the deflector, as you will have to run the light wires thru the little maze. The above picture has my middle light pushed down. Yours should be up in the hole so that the light leads do not ground out on something. Remember the LCD panel is surrounded by metal and it would be very easy to ground this wire out on the panel.

Turn the PCB back over and desolder the deflector. The deflector is plastic and has two feet that some thru the PCB. I touched them with the soldering iron to soften the plastic and then pulled it it off. Next desolder the lights. Follow the lights traces from the front to back and make sure and desolder in the right places. My lights came thru where you see all of the melted crud above. (this picture was prior to cleaning it all up) I actually had to slightly tug on the wires while I was soldering to pull them out. It would be very helpful to have a third hand at this point.

Once the lights are removed, it is time to put in new ones solder them down. Be careful to use only small amounts of solder and not to jump any traces with run away solder.

The two side lights require only short leads while the middle requires longer leads routed thru the deflector panel maze. I did the two sides first then ran the center lights with very long leads, mounted the deflector, and soldered it into place by melting the plastic legs on the rear side of the PCB. After I had the deflector in place I was able to route the wires and solder the center light down. Once it is all done clean everything up ensuring that wires will not ground out, or solder does not short a trace.

I tested my lights, actually I did one at a time but you only need to do it once, prior to putting all of the pieces back together. Keep in mind that the display will read funny unless you mount the LCD feet back in place, turn the tabs and solder them down. I tested mine by plugging everything back together with most of the screws still out. Be really careful if you do this as you can short the radio very easily by grounding something out

Reinstall is reverse,

1) install the LCD PCB

2) put on the faceplate

3) Guide the ribbon cable into the connector with the tape mechanism out or partially in.

4) Then using a small screwdriver lock the ribbon connector into place. You will have to put the screwdriver in the small area near my thumb in the above picture.

5) Put in all the screws and plug it up, your display should look like new.

Martin