Blaupunkt "Hamburg" SQM 23 buttons not remembering + bulb burned out

Chris

There is definitely a memory circuit that should have 12v when the key is off to maintain your presets etc.

If I remember correctly Mercedes from that period have European style fuses and I can't remember what other things might be on that same circuit that would now be not working if the fuse were blown possible the cigarette lighter?

Are there any other electrical items not working in the car?

I would check the fuse box first I recommend using a meter not a test light but that's your call and if all fuses are good pulling the radio is the next step again the meter will come in handy here checking the plug on the back of the radio for power and ground connections.

If all that tests ok then the problem would be on the radio and fix or replace would be your two options at that point.

Good luck