Becker Bavaria C professional RDS help

[Casss]

Sorry to bump up this old thread; however I am hoping some of the enthousiasts are able to help me out.

I currently own a 750IL originally equiped with the BMW Bavaria C Professional RDS. As far as I know this has also been used in E31.
To be more precise, the system has the following components;

- 'Bedienungsteil', or head unit specified as BE1801.
- 'Empfanger/verstarker', or receiver, mounted in the trunk. This one is also specified as BE 1801.
- Remote control, installed in rear middle armrest, specified as BE0946
- CD changer installed in trunk
- Amplifier installed in trunk

The (first) issue I am facing is related to switching on the radio.

After connecting the radio and the battery to the original wiring, the red alarm LED starts blinking.
After putting the ignition switch on accesory position, the LED stops blinking.
Pressing the Power button on the radio results 99% of the times in exactly nothing, 1% I see a split second an 'orange' flash. Not sure if it is the background ilumination or the displays.

If I try switching on the radio through the power button in the remote control, the display in the remote lights up and I can hear a couple seconds 'humming' from either the CD changer or the Receiver.
Then, after about 10 or 15 seconds, the light in the remote switches off again. No symbols are displayed in the remote control display.

So far I diagnosed;
- fuses in the radio, cd changer and receiver are working and replaced where needed. Two were broken.
- I had the headunit tested at a local electronics shop, where they stated that at least the Power button works as it should, however they are lacking documents/circuits to allow further diagnosis.

Does anybody have a pointer for me where to look to resolve this issue?

[Omega man 1969]

The Head unit and the tuner in the boot must both have power and the data cable plugged in, in order for the head unit to switch on. Confirm you have power to the tuner unit by testing the power input connector with a multimeter.

I have 2 spare working sets should you need one.

Sorry to bump up this old thread; however I am hoping some of the enthousiasts are able to help me out.

I currently own a 750IL originally equiped with the BMW Bavaria C Professional RDS. As far as I know this has also been used in E31.
To be more precise, the system has the following components;

- 'Bedienungsteil', or head unit specified as BE1801.
- 'Empfanger/verstarker', or receiver, mounted in the trunk. This one is also specified as BE 1801.
- Remote control, installed in rear middle armrest, specified as BE0946
- CD changer installed in trunk
- Amplifier installed in trunk

The (first) issue I am facing is related to switching on the radio.

After connecting the radio and the battery to the original wiring, the red alarm LED starts blinking.
After putting the ignition switch on accesory position, the LED stops blinking.
Pressing the Power button on the radio results 99% of the times in exactly nothing, 1% I see a split second an 'orange' flash. Not sure if it is the background ilumination or the displays.

If I try switching on the radio through the power button in the remote control, the display in the remote lights up and I can hear a couple seconds 'humming' from either the CD changer or the Receiver.
Then, after about 10 or 15 seconds, the light in the remote switches off again. No symbols are displayed in the remote control display.

So far I diagnosed;
- fuses in the radio, cd changer and receiver are working and replaced where needed. Two were broken.
- I had the headunit tested at a local electronics shop, where they stated that at least the Power button works as it should, however they are lacking documents/circuits to allow further diagnosis.

Does anybody have a pointer for me where to look to resolve this issue?

[Casss]

Thanks Omega man, I appreciate your effort to help!

This morning I tested the power to the tuner, it does get powered. I measured close to 12 volts on the power cable. As far as the data cable goes, I have two round connectors plugged in into the tuner. Those cannot be put in the wrong order, the can just be installed in one way. The connectors are in good condition, no oxidation is visible on the pins.

For what it’s worth; I had previously also experimented with connecting a BMW Bavaria C Business RDS radio, which also has the additional square connector on the back of the radio. That radio did switch on. (I couldn’t diagnose further as I don’t have the radio code).

Is there a way to test the signal that is supposed to be given from the tuner to the headunit? Or can I create a ‘substitute signal’ to test the head unit?

[Omega man 1969]

The head unit will turn on and display "code" if the tuner is unplugged. You may need to shine a torch at the display as likely the orange back light LED's have failed.

- - - Updated - - -

You can't "trick" the head unit into thinking the tuner is plugged in, the tuner has an EPROM with a security code that matches the head unit.

[Casss]

It does not display Code as far as I can tell, also with a torch shining at it in different angles, no letters or numbers can be seen in the display. Do you by chance have the service manual for the headunit? I though I purchased it, however it turned out to be the service manual for the tuner.

[Omega man 1969]

Yes I have the schematics for both somewhere. If you open up the head unit, look at where the power enters the PCB and check to see if power is present. I'll take a look for the Schematics.

[Casss]

🙏 thanks! I would also be interested to see the pin allocation for the front facia of the head unit.
If I know which pins power the backlight and provide ground I could further test it. I did measure the backlight LED’s, all tested good, except 1 I was not sure of if I recall correctly. However, one defective LED shouldn’t be an issue as I have seen pictures of radio’s working fine although not every part of the display was backlit.

[Omega man 1969]

On the large display you can one LED out and the others on. On the smaller display that displays "CODE" just 1 bad led will take the lot out.

[Casss]

Both displays remain 100% dark, so that makes me believe the problem is at a different level.

[Omega man 1969]

The head unit is fairly basic inside, can you remove the lid then undo the screw holding the main power connector in place, behind that is the power input components. The screw is located inside the back of the main connector. Lets see what's going on in there.

Actually, that section of the unit may be really tricky to get at, I think there is a voltage regulator behind that connector. I will check the schematics....if I can find them :-)

[Casss]

Great, lookiny forward to the schematics! You posted also a picture of the inside of the head-unit in this thread btw, message number #12

[Zerorynkar]

The head unit is fairly basic inside, can you remove the lid then undo the screw holding the main power connector in place, behind that is the power input components. The screw is located inside the back of the main connector. Lets see what's going on in there.

Actually, that section of the unit may be really tricky to get at, I think there is a voltage regulator behind that connector. I will check the schematics....if I can find them :-)

Hi i just installed this complete system in my e34 m5 restoring back to original have a few questions are you in the US by chance? If so can you call me 330-281-0078 or email me if you are out of state

[Ricibmw]

Hallo omega

i need help my 850 csi radio, becker be 1801 + hifi, if i switch on display ligt very low and if i give code , switch off and to after plug out and in battery not funkcion its so possible help with me for this radio ? Please give me message to my email tajzler1@gmail.com Thanks a lot richard

[niz93]

всем привет)

i have non work CDC BE982, it doesn't read CD's, but he is determined by his head and communicates, changes disks

photo_2024-01-02_17-30-57.jpg

I sniffed the communication protocol in different possible modes and got some results, you can study in more detail in the archive in particular "CDC to Head command"

I was able to communicate with my head by forcing the amplifier to be activated in CD mode, for this I used usb-rs485 and PComm Terminal Emulator

Screenshot 2024-01-02 171041.png

photo_2024-01-02_17-30-56.jpg
example:

1 send insert CD info


FC1032032C23FF2E0F LOAD или CD (all 10 CD insert) //transmits information about the number of discs in the store


2 press the button 1 (or another number) on head (head will show LOAD *number* or send LOAD command


FC1032072B010000000001F10F LOAD 1


3 send CD info command


FC1032072BB10000000001410F CD 1


after this the head will consider that it is working with СD 1, repeating steps 2 and 3 with other numbers you can change the disk numbers