I am referring to the ibus RRs. which have the extra LEAR amp in the boot.

It has come to my attention, that when the battery dies, these amps stop working. I have received a lot of phone calls, where sound has stopped working completely, but the bm54 still working.

The first assumption is the BM54 at fault.

At first I didnt believe it was the BM54 unit, as when I received them, they worked as normal. After finally, getting my hands on a RR, I was able to find the cause. I think!

I will know for sure, once I have tested and repaired more BM54 units. It should be a lot more straight forward, now that I know what to look for.

I want to save people from having to try and source one of these rare LEAR amps!

BARIS, you come as an angel to me, from 7 months driving without sound, and I've tried everything, the radio module work as well, and I believe the problem was the dsp lear from the first time.
many people told me that the problem was the bm54,(also reading here) but I've always had and belief that my amp blew up.
Now, you confirm my hypothesis, so I hope I can solve.
think I have to change amplifier?thanks

First things first. There are a few tests you can do.

1. Use a multimeter to measure the voltage coming out of pin 13 of the bm54 connection. If its not 12v, then the Lear amp is not getting the signal to switch on.

2. Connect a 12v connection to pin 13 of the bm54. This is for test purposes only, so do not do this as a permanent solution.

If the voltage is low, then the bm54 is repairable.

This is one type of fault, I'm sure there is plenty of other faults out there.

Baris, I checked the output voltage (pin 13 bm54 to pin 8 DSP) and seems to be ok (12.7v) the radio module work correctly, also because I have no audio from either nav.
do you think the DSP? can be repaired?

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Ok, so the DSP is getting the correct power. Before putting the fault with the DSP, there is one more test to do in the bm54.

Pins 1-8 are speaker outputs, you should only have middle ones connected, which are pins 2,3,6,7. There should be 6 volts coming out of these. Alternatively, if you have some spare speakers, connect up the back of the bm54 connection and see if you get any sound.

Better off without DSP anyway sounds awful....

Thank you Baris , I will check now, bm54 speaker output, can I connect spare speaker into dsp connector?because I can't get the radio connector . alternatively can be fit Harman Kardon logic 7?

I tried to see if spare speaker can work connected to pin 4- 9+ and/ 5- 10+ on the DSP conector (X18773/26) but no result, AND no audio. I tried with dsp not connected),. I noticed that the radio time during the search does not find anything. in this case can be the radio module the problem.. I would know because just yesterday I took a dsp on ebay, and I would not be useless

I appear to have lost some of the channels, the sound is full of base and muffled, any chance of this being fixed by you baris?

Regards
Steve

Check the plugs that go in to the amp, the pins are most likely corroded due to water ingress or the amp circuitry is damaged

Hi Steve,

I suffer the same as you on occasions. Mine seems like a lose wire or something as it works fine for a while, drive over a couple of bumps and I get a crackle and then sometimes all the car speakers cut out - I;m left with just base from the boot area ( I think ). Turn the radio off using the push button and then straight back on again and it all comes back. sometimes for days and sometimes for minutes until I hit another bump (or a tight left turn funnily enough !)

Baris - Is this more likely to be the dsp amp.? Ash
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2016 SDV8 AB

Andrew, if you have no speaker output from the bm54 it very well must be the bm54. What do you mean by, you can't find radio stations? Can you search for radio and flick through the modes?

Comports, that sounds like a DSP fault, if you can still control radio stations. Check the pins on the connection.

Steve, I recently had someone come with the same symptom, and the fault was with the DSP. Had to replace the DSP in the end.

Update Baris

My sound went again tonight. I have full control of the radio stations still and everything else up front. I do hear the radio still but it seems only the low (bass) channels. They do still come from the car door speakers but very quiet and bass'y.

Does this suggest the DSP is on it;s way out, can it be repaired by you or is it a replacement I;m looking at.? Ash
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2016 SDV8 AB

Turn the DSP off - sounds better

I wonder if that will confirm the issue though. If i just turn off the DSP (via the screen options) and see if the radio/sound cuts out again. If not then it's deffo the DSP AMP that's goosed..? Ash
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2016 SDV8 AB