BMW Amp - Page 1
Forum section: electronics / general

author: gamozo
author_rank: Regular Contributor
timestamp: September 21, 2011, 08:58:52 pm
content: So... due to a major flaw in the BMW Z4 design, I ended up with about 3cm of water pooled in the compartment that holds the battery and the amp (leaks through the trunk). Obviously, this has royally messed up the amplifier. A few channels of audio have gone out, and I've taken the amp apart once (there was some slight charring on an IC, a few surface mount resistors and caps, and a transistor. I'm gonna poke around at it today with actual test equipment and see what I can find.I've never really done failure debugging like this before, so I'm looking for some tips (or guides somewhere) that would be helpful to read for debugging. All I could think of is taking individual components off, looking up the specs, and testing to see if they work as designed. Obviously caps and resistors I can probe to see if they're working properly.I'll get model numbers and pictures once I get home and take the amp apart again.-Brandon Falk

author: FenderBender
author_rank: Super Contributor
timestamp: September 22, 2011, 12:42:33 am
content: BMW won't help you out and either fix the problem or give you an amp?If there are a lot of smd chips etc., it might be harder to fix.

author: gamozo
author_rank: Regular Contributor
timestamp: September 22, 2011, 12:47:15 am
content: Nah, BMW won't help. This is an extremely common problem in Z4s, yet they've not resolved it, nor given any cheap deals on a fix. So I'm just gonna fix the amp (or get one from a junkyard for $100), and go from there. Nowhere have I seen people fix the actual leak, so I put a towel where it was leaking and that fixes the issue. If it gets bad, I'll put some drain holes in the compartment so the water can no longer pool... pictures will be edited onto this post in a few minutes.

author: NiHaoMike
author_rank: Super Contributor
timestamp: September 22, 2011, 01:07:29 am
content: Replace it with a generic unit.

author: gamozo
author_rank: Regular Contributor
timestamp: September 22, 2011, 01:19:00 am
content: I would replace it, or get a generic unit. But for a new unit, it's $600-$900, and about $100-$200 for a used one. Right now, I could care less about the audio, as I'm fine with a few speakers out. If I sell the car, then obviously I'll try to replace it. Until now, it's just a little hobby repair project, that could save me loads down the road.Pics (start at the case, then at the end it's focusing on the worst looking components):https://eesdb.org/bmwamp/

author: FenderBender
author_rank: Super Contributor
timestamp: September 22, 2011, 09:45:54 pm
content: I'd try cleaning it off with some PCB cleaning solution or some rubbing alcohol. I can't say that I even seen any charred looking chips. I do see a lot of water mineral deposits and dirt. Perhaps just those minerals are enough to short some of the smaller parts out. Maybe try it again after you clean it up.If you do see chips or components that are dead, replace them...obviously. I'd clean it off first, so you can distinguish what is good and what is bad.

author: gamozo
author_rank: Regular Contributor
timestamp: September 22, 2011, 10:49:57 pm
content: Yeh, I'll give cleaning it a shot. After that, it's time to test chips! That transistor (that I gave a closeup on) had so much buildup. If the buildup is conductive at all, I'm sure it would short there.

author: FenderBender
author_rank: Super Contributor
timestamp: September 23, 2011, 03:25:58 am
content: I had the same problem with a small SMPS that got flooded (while plugged in) when Irene came. Forgot to take it off the floor. Anyway, opened it up. Lot's of that residue...but it still failed to work properly even after I cleaned it off. It most likely killed the smaller chips that aren't as rugged. I tested the main MOSFET which I suspected had gone wrong, but it was in fine shape. I lost interest in trying to fix it, but I'm assuming it was a small SMD devices on the back of the board. Nothing else looked too wacked out.

author: Sionyn
author_rank: Frequent Contributor
timestamp: September 24, 2011, 01:41:06 pm
content: this reminds me of the boiler pcb with the 'engineer' wanting to replace it with a 200 quid replacement for one failed cap

author: dimlow
author_rank: Frequent Contributor
timestamp: September 24, 2011, 03:12:38 pm
content: Ditch the pose waggon, go out and buy a real car