OEM Stereo notes (C33, C43, CD43, CD53)

Jan. ’17: I’ve acquired many OEM BMW stereo units recently – a CM5908, CM5903 (C33), a C43 and a CD43.

The CD43 was quite a challenge to unlock, had to get a specialist involved. It’s since gone to a new owner via eBay (Thanks!), so I’ll focus on the less loved cassette models.

The C33 won’t make any sound. The C43 powers up. I managed to clear the CODE WAIT message; I’ll get the actual code from my dealer later on. If you get a CODE WAIT, just leave the unit powered up for about two hours. It’ll eventually switch over to the CODE ____ display, ready for your anti-theft digits.

I’m also tempted to take the “amp” apart to see what makes it tick. Apparently the E24/E28/E30 “BMW Premium Sound” Blaupunkt amp is more of a passive crossover, along with a few capacitors slung on the Nokia speakers. Later cars have more speakers…but it seems many drivers care little for the quality of BMW’s sound systems. Next time I’m in the yard, I’ll be digging out a high-end unit from a more recent BMW to see what the next generation looked like. I’ll be looking for one of the Logic7 units, or the near-interchangeable HK system.

Feb. ’17: I found a near-complete Harman Kardon system whilst scrounging a local pick-n-pull yard this weekend! Pulled a partial HK system from an E46 (nine speaker). I got the amp, trunk bracket, both subwoofers, both tweeters, a few door speakers, wiring harness, antenna, loudness button, and the E46-style CD43. Lots of chopping to get at the harness…updates will follow once I get it all set up.

Of course, this will all have to wait until I get more units in stock. That nearly-perfect CM5908 at the top went off to New Zealand for a concours 325i M-Tech restoration. My last C43 is now sitting in a Z3 in Georgia. I’m jealous, always wanted a roadster…at least it’s being enjoyed! I also found a nice Alpine CM5908, but it was under-packed & mangled on the way here by USPS and now won’t make any sound. 🙁 I still have an E46 CD43 that I need to unlock (I need some iBus data and an IKE apparently).

Jul. ’18: I’ve picked up a scruffy CM5907 and another Alpine CM5908 “pyramid” in far nicer condition.

Aug ’18: The nice CM5908 sold to a Romanian via Canada along with all my “BMW Premium Sound” harnesses & amp. I guess it’ll be a while before I do any analysis of the Blaupunkt amp since I don’t have anything to analyze. So I’m down to three OEM units. The E46 CD43 is (apparently) a CD53. Who knew? It’s the earliest version, relatively unreliable and not aware of stuff like iPods and other external audio sources. The ratty CM5908 was successfully dismantled (by me) and found to have a few failed capacitors in the final stage. I’ll be attempting a repair if the unit doesn’t sell first. The CM5903 most likely also has failed outputs. Testing will continue!

The CM5908 is out of surgery…feast your eyes on this awesome bit of 80s technology! Can’t you almost hear the Scorpions playing? 😉

I also took apart one of the C33 units to check out the cassette transport. Ugh. The rubber drive belt is a sticky gooey memory. There is just an outline of where it once existed. What did they make that stuff from? It looks like it’s been abducted by aliens! I’m told that a VCR repair kit (seriously) might make it all OK again. I’ll see if I can get the thing back together until I find the right parts for restoration. The cassette mechanism is challenging. It’s surprisingly intricate and rather tricky to put back together again.

Bonus…here’s some unrelated links relevant to BMW stereo hacking: BimmerBoard E34 amp with stock Nokias here. RGB settings here at R3v (LCD – R 35 / G 10 / B 5; Keys – R 16 / G 12 / B 11). Recommended 5-channel amp there too. E34 amp overhaul notes here.