Voltage unstable - causing speaker crackling

[cyne]

Hi all,

I just made a revelation today.. ahhaha.. I am seeing a relation with voltage dip and losing the right side speaker sound.

When car is running, voltage at 13.5V above Max is 13.7V. Eveything is ok. But when I move to a stop, nearly to a complete stop. Realised that my voltage will drop below 13V and then the speaker will crack and lose sound. And when my voltage goes back up to 13.5V everything is normal again (right after i completed my stop and idling)

Question... do I have a bad alternator or a bad battery ? My battery is tested ok with my home multimeter at 12.6V with everything off.

 

[aidilj]

bro cyne, this symptom points to the alternator. Similar to mine last time, battery is new, on the highway no problem, when slowing to a toll suddenly ASC light goes up. From then on it starts getting worse.

 

[cyne]

Touch wood, till now.. everything still works fine. Just the speaker cracklings. Could be other things ?

 

[jarance]

All speakers or just one speaker?

If one speaker or two speakers, check for the loose connection at the speaker.

 

[cyne]

Just the right hand side speakers. I was assuming that the speakers are all fibre optic cables. And the sound will come back after the car has been moving more than 30mins. And the first post symptoms will still continue.

Is just that currently, cold start, there will be no sound. After 20mins, the sound will crackle like it's waking up from its slumber. Maybe after 30-40mins, sound will completely return.

And when have a stop, the sound will go out for a second and come back up again...

 

[jarance]

According to BMW WDS, there is no fiber optic from the amplifier to the speakers. They are wired up with copper wires.

The front tweeter and mid range speakers are wired in series. That mean if the tweeter is not working, the mid range speaker will not work.

If the cracking sound is observed in the mid-range, it will also pick up by the tweeter. However, you will most probably cannot "hear" this as the cracking is more toward the low frequency range rather than the tweeter high frequency range.

 

[jarance]

When you are driving and cracking sound comes, stop the engine and see whether you still have the cracking sound.

This will eliminate the noise from the alternator.

 

[cyne]

Every time when I stop, the speaker(S) will lose sound. So I guess my amplifier is shot in this sense.

 

[cyne]

Ok, I think again, I just found the culprit. It's the ASK unit that's f***ed up. I've replaced the rear trunk amp with no luck. And found this link

http://www.diyparadise.net/cd_ask_repair_kit.html

Just for anyone that has this problem. Don't need to crack the head to find out...