Soundsystem stop working at exact 13.0V

[M*I*B]

Hello dear people...

...first of all: please excuse my bad english...

I have a 540 Touring from 2000 (bfl). A 16/9 display is installed, a BM24 and a MK4 with current software (should be 30.2).
For some time now, the system has been stopping the sound while driving. The display can no longer be operated when it comes to CD (replacement) or radio functions. It can only be switched off, but not switched on again. Everything is fine at the stand.
At first I thought it was a loose contact and/or cold solder joints, so I treated all the connectors with K41. When that didn't help either, I disassembled the BM24 and the control panel and re-soldered all the soldering points (contact connections, power parts, wired components). Unfortunately that didn't work either.

So to summarize again:

1. Ignition key on garage or ignition
- Everything works perfectly normally all the time
2. Engine on
- After a short time the error image.
3. Engine off
- Everything's fine

Then I joined in and connected an adjustable power pack (homemade, 12-15V, 80A max) to the back of the battery and, starting with 12.4V, always increased it by 0.2V, tested it and increased it again by 0.2V and tested it.
It turned out that exactly at 13.0V, reproducible several times after switching off the radio, it could not be switched on again.

That's weird, isn't it?!

I suspect that a system somewhere has a defective voltage regulator or something similar, which then stops working.
And now you come into play.

Question 1:
Which device does the on/off switch of the control panel primarily affect?
Does it affect the amplifier and then all the other modules? Or something completely different?

Question 2:
Highly unlikely, but is anyone familiar with this error?


Greetz
Micha

[shogun]

Thread moved from E39 Common Problems and DIY Fixes to E39 forum, questions post in E39 forum

[crdiscoverer]

When you were measuring in 0.2V increments, did you simply look at the head unit switching off at 13V? Or did you hook a multimeter and you saw no power being delivered to the harness?

[M*I*B]

@ shogun:
Thx for moving to the correct area

@ Eric:
I use of course one of my Multimeter. My DIY power supply has a fairly accurate display and a 10-turn pot for setting, but I referred to the voltage that is present at the BM24 (PIN9 big). I used a "Metrix MTX 3290" yesterday, but only because I couldn't find my inexpensive Uni-T Since I am an electronics technician by profession, I also value good tools in this area.

This morning I had the inspiration on the toilet (yes, I often have good ideas there ) to supply the modules individually with the power supply one by one, i.e. always all the others on the board network below 13V and only one on the power supply. If then a module exceeds 13V and the error occur, I have catch the broken one (I think)
However, I am still missing the pin layout of the power amplifier (without DSP) and the control unit (head unit?) to well can going this way. The Navi can't be the one due it makes no different if present or not.

Greetz
Micha

EDIT say: Have find the Pinning of the PA here at BF...
EDIT also say: I am not able to find the pinning of the control panel / (head unit?), even in WDS-online. I guess I just don't know how the control panel is actually called there ...

By the way:
Does anyone know why the 16/9 unit still displays a 4/3 image despite the MK4 Navi being connected with software 30.2 (I mean)?
I hadn't installed an MK4 for years; something else was always more important. But in the course of the error I had now connected it and found that it didn't work. The colors and the display are completely different and the tags of the MP3-CD simulator are now displayed correctly, but not in full-screen format

[M*I*B]

Got him! The BM24 bitches. Do I have to get a new one... Or does anyone have a schematic of the BM24 or know where I can get one?
DirtFix: Two power diodes in series (or a bridge rectifier) to PIN5 = about 1.2V less. Works for now ...

[edjack]

Our Old Pal Dennis Cooper ( a major contributor on this site) will no doubt tell you that these units are 20 years old, and are subject to failures. You may have more failures.

He would recommend that you replace the system with a top quality Chinese unit, like the Dynavin. There are other non-OEM-appearing alternatives from major car audio vendors.

We are fortunate here in the USA that we have a national support person for this brand.

[crdiscoverer]

Given that Dennis is in the UK and the OP in Germany, he can definitely give him a hand.

For sure he won't recommend a Dynavin as a first option, lol. In fact, that's one of the last things he will suggest you do.

[M*I*B]

... at 1st thx all of you ...

And yes... Sometimes I think about installing a China hit there. But then it's no longer original, which I'm a bit reluctant to do. In addition, such a conversion is an expensive fun; Unfortunately I can't shit Teuros yet...
I have a lot of other stress at the moment, but if I find time afterwards, I'll start troubleshooting. Even if I can't find a circuit diagram by then, my ambition as an electronics engineer dictates that I at least try to find the defective component(s).
I am aware that electronics is gradually giving up after more than 20 years; it's just not a vacuum-tube system. But as long as I can hold a soldering iron and use a scope, I won't give up...

[BimmrMeUpSnotty]

The soldering joints on the circuit board start to crack at this age. Could be something simple like that, could be old capacitors bulging out and just need to be replaced. The way I see it, the OEM sound systems were a joke when they were new, I would just spend the money, rip the old junk out, install in a decent sound system, enjoy the drive.

[M*I*B]

Just an update and a question...
updated:
Found the fault semi. Was a SMD voltage regulator as expected, which supplies a part of the processors. Fortunately, the nominal 5V simply dropped to around 2V as the input voltage increased, so that there was no further damage. So the topic is over for the time being.
Annotation:
Of course, such old devices have problems with cold solder joints and contact corrosion due to the enormous fluctuations in temperature and humidity. Nevertheless, you should show me a current device/system that survives at least 5 of the now 22 years under the same conditions. Leaded solder already had its advantages over today's unleaded solder. That's why I still build all my own developments with leaded solder...


Question:
Irrespective of the above, the question arises as to which of the so-called China crackers comes close to the quality of the BMW system. Because the receiving system of the BM24 with diversity is certainly one of the best systems I know. A China cracker has to reach it first!
My demands are at least not below the BMW system. That means, on the one hand, it has to look as similar as possible to the original control panel, on the other hand, it should be able to be integrated into the existing system, including control via the bus (steering wheel buttons), muting on phone calls (original BMW phone with spiral wire) and other things.
And if it must be a "modern", then please with the option of using either a SIM card for mobile data for navigation purposes (Google), or data via BT Tethering with the existing SmartPhone. And of course the FM (UKW) receiver should at least come close to the BM24 in terms of quality...


Suggestions?
The Dynavin N7 Pro looks well, but is it that?

EDIT say:
What's about the D8-E39 Pro 160 GB ? Have anyone buy that and can report about it?