hifi (10 spkr) shared earth to front speakers - The Unofficial BMW M5 Messageboard (m5board.com)

1day · 30th June 2009, 12:50

my 34 m5 has a 10 speaker system in it (becker headunit, tuner, cd player, bmw / bluapunkt amp / crossover)

The front passenger dash and door pilar speakers have stopped working, footwell speaker is still working though.

- examined the footwell speaker and wiring, no obvious issues.
- took out both non working speakers, found that the pilar speaker positive connector housing (plastic) had collapsed, and the connector was (previously) soldered to the cone pickup (hair thin copper wire).

presume that as the two non working speakers share an earth (see attached wiring diagram), that the door pillar speaker being broken is causing the dashboard (mid range) to stop working as well.

i think this is the wiring diagram... but I'm not an electrician therefore don't understand wiring that much, and can't see where the "shared earth" connection actually is to check it?

any advise greatfully received, I have a mutli meter but don't really know what I'm looking for...

Konfused Pete · 30th June 2009, 13:46

In that diagram all three speakers per side share an earth. The join point, marked as connector x826 left and x827 right is a splice not a connector, meaning somewhere between the amp in the boot and the speakers in the front it is solder-joined.
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disconnecting one won't effect any of the others so try disconnecting only the pillar tweeter. other two should work.

If you have a multimeter, set it to AC voltage and jam the probes into the connectors which attach to the silent speakers and there should be a voltage. if you get nothing, you're getting no signal to that speaker. test the voltage on the one you know is working to get a feel for what you're looking for.

woods · 30th June 2009, 19:03

Try cleaning the connectors attached to the amplifier in the trunk... I just repaired the exact same problem and it was just a continuity problem at the connector. The connector had worked itself a little loose and there was a bit of corrosion causing the front left mid to cut in and out. Problems solved after a good cleaning.

Each speaker gets its own filtered signal from the amp unlike other cars.

1day · 1st July 2009, 20:49

been too hot to work in the car last couple of days - hoping to multi meter later :-)

1day · 2nd July 2009, 12:43

Quote:

Originally Posted by woods

Try cleaning the connectors attached to the amplifier in the trunk... I just repaired the exact same problem and it was just a continuity problem at the connector. The connector had worked itself a little loose and there was a bit of corrosion causing the front left mid to cut in and out. Problems solved after a good cleaning.

Each speaker gets its own filtered signal from the amp unlike other cars.

swapped the connectors from the tuner to the amp, ie connected the front outputs (tuner) to the rear inputs (amp) - sound comes through the back speakers - so presuming the connectors are ok.

back connectors to front speakers - still no sound from frotn left, so, speaker / wiring fault is in the front passenger area.

I think thats what the above test proves....?

1day · 2nd July 2009, 12:51

Quote:

Originally Posted by Konfused Pete

In that diagram all three speakers per side share an earth. The join point, marked as connector x826 left and x827 right is a splice not a connector, meaning somewhere between the amp in the boot and the speakers in the front it is solder-joined.
---------------------
disconnecting one won't effect any of the others so try disconnecting only the pillar tweeter. other two should work.

If you have a multimeter, set it to AC voltage and jam the probes into the connectors which attach to the silent speakers and there should be a voltage. if you get nothing, you're getting no signal to that speaker. test the voltage on the one you know is working to get a feel for what you're looking for.

disconnecting just the door tweeter didn't make any difference (and it was in that condition anyway, as the spade connector has seperated fromt the speaker pickup (ie it's broken - photo attached).

did the multimeter tests (before the sun made it too hot to work in the car).

here they are - still don't understand tbh.

V~ (200 setting)
left front door tweeter - 11.0
left front DASH tweeter - 00.2

Right front door tweeter (working) - 00.0
Right front DASH tweeter (working) - 00.0

V---... (20 setting)
left front door tweeter - 6.4
left front DASH tweeter - 0.06

Right front door tweeter (working) - 00.0
Right front DASH tweeter (working) - 00.0

Ω (200 setting)
left front door tweeter - 0
left front DASH tweeter - 0

Right front door tweeter (working) - 6.6
Right front DASH tweeter (working) - 4.5

any help interpreting these readings much appreaciated.

also - the colour codes on the wiring diagram are in German - these are the actual colours - do they tie up (I don't speak any German :-( )

left front door tweeter - yellow green (+) yellow brown (-)
left front DASH tweeter - yellow white (+) yellow brown (-)

Right front door tweeter (working) - blue green (+) blue brown (-)
Right front DASH tweeter (working) - blue white (+) blue brown (-)

thanks
Jamie

woods · 2nd July 2009, 21:49

Quote:

Originally Posted by 1day

swapped the connectors from the tuner to the amp, ie connected the front outputs (tuner) to the rear inputs (amp) - sound comes through the back speakers - so presuming the connectors are ok.

back connectors to front speakers - still no sound from frotn left, so, speaker / wiring fault is in the front passenger area.

I think thats what the above test proves....?

This only proves that there is no signal getting to the front speakers from the amp. The wiring from the head unit to the amp is OK. The problem could be anywhere between the amp and the speaker. Test if the wiring is OK by pulling off the connector at the amp and checking the continuity of the line to the speaker that's giving you trouble (using a proper ohm-meter and some *long* leads).

That said - I would try cleaning the contacts at the amp first.

kalevera · 2nd July 2009, 23:43

The hifi harness is segmented in such a way that there are splice connectors for the door tweeters (2 pin), an 8 pin connector for the dash speakers at the left front of the car (this is on LHD cars), and if memory serves a further connector for the RH woofer and door tweeter on the right side. The amplifiers do go bad, and that's the first thing I'd check. Beyond that, I'd inspect those splice connectors...