I was just repairing a BM6000 display and remembered someone asking for a guide on repairing the LED-Displays in the Beosystem 6000/8000 components some time ago.
And so here it is (should be very similiar - if not identical - to the displays used in the Beocenter 7000 series):
First step:
Desolder the display from the circuit board (self-explanatory, isn't it? So no pictures here). Before you do so, make a sketch to remember which digits are not working.
Step 2:
Remove the white and red plastic parts on the back of the display using a knife or something similar.
Step 3:
Now you should be able to remove the red plastic cover and the newly revealed white plastics. What is left now is the bare circuit board.
Step 4:
Now you can see why these displays fail that often. The thing in the middle of the black spot is the LED itself. And then (barely visible) there is this thin wire running to the contact left of it. This wire is not soldered, it is just pressed (maybe also glued?) on the board. So with time it just loosens and thats when the digit stops working.
Step 5:
So all in all it should be a simple fix - sadly it isn't. Theoretically it should be enough just to add one tip of solder to every of the wire contacts. The difficult part: Don't leave the solder iron there for too long! About one second should be enough - otherwise you can damage the LED. In my case this worked for most of the missing digits - sadly not for all. Two of them were completely missing the wire - no idea if it was my fault or if it already was like this...
If there were no missing wires on yours - reassemble it and test. If some digits are still not working: Remove the plastics (but leave the display soldered on) and try to solder with the display switched on. You can immediately see if it worked and sort out the usual bad contact problems.
The following steps are optional and only required if you couldn't fix all the digits with the steps described above.
Step 6:
Order some red SMD-LEDs. You can get them very cheap in online shops. I ordered mine here.
Step 7:
Scrape off the old LED (the black spot).
Step 8:
When you unpack the new LEDs (beware - they are really, really small) you will see a marking on the back - usually a small triangle. The vertex of the triangle must point to where the black spot was. Well, and now you just have to solder them on. Pretty easy, isn't it?
I hope this will someday help someone repairing this BM/BC.