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Becker BE 3100 Auxiliary input

28K views 6 replies 5 participants last post by  raymond- 
#1 ·
You can skip all the explanation gibberish and Go straight for the first step I tried to make it as clear and organized as possible
One of the first things i attempted On the W210 is the aux conversion, because simply the radio sucks !
On the Daewoo Nubira and the Hyundai Santafe there were three pins labeled L-GND-R To remove and replace with the aux input, which made the job very easy, but this damned becker had nothing,

i decided -using the service manual- to solder the aux input on the Processor ic's Output(Pin 24 and pin 7), but the volume was too low


so i connected it directly to where the tape head connected , but the gain was really high ! and all i got was distortion (basically sounded like crap)
since the output voltage from the phone was higher than what the processing Ic is expecting (phone output is close to 1.5volts and the head's output is in millivolts ) so i decided to lower the input voltage using a simple voltage divider and this is how i did it

A-Getting the Becker out
(Make sure you have the headunit's code, though it can be acquired online using the units serial number)

A1-i used a two nail clipper instead of the special keys


the clippers file (or what ever its called) is inserted in the hole and pushed outside while pulling the tape outward ( i used only one and kept alternating between the holes

how the lock should be pushed inside using the file.


A2-After Pulling the headunit out, i removed the connectors and the antenna cable.



B-Disassembly and modification.
B1-The units model is be 3100 which was used to get the service manual.


B2- the top cover is pried from the back using a flathead.


B3-After removing the Four Torx 8 screws holding the cassette player, the player is pulled out.


B4-Cassette head's cable is removed using a soldering iron.



B5-Aux input cable is soldered instead of the heads output and pulled from the back and whole unit is reassembled .




B6- Two 50k seperate potentiometers for each channel and two 150k ohms resistors are used to make the voltage divider circuit(used this Circuit Simulator Applet for demo).



C-Assembly and testing
C1-Drilled a hole in the cubby for the aux 2.5 trs wire and connected the headunit.


C2-The phone is connected at lowest volume and the headunit at normal volume, and a cassette is inserted to fool the headunit that there's a cassette playing .

C3-The volume on the phone is raised slowly and the potentiometers are tweaked to reach a good level for playback.
C4- Headunit is put back in its place .

C5- Enjoy your favorite tunes.

Two additional things can be done here:
1-The pots can be hidden inside the headunit, for there is plenty of space for this
2-The resistance of the pots after tweaking can be measured and replaced with constant value resistors.
but i like to be able to tweak them any time i want so this is what i ended up with :y.
3- The eject can be desoldered so that nobody can remove the cassette after insertion
 
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#7 ·
The BenzWorld administrators have asked that we not assist with radio code security bypass for liability reasons. If you search online and the w210 STICKY there are others who have posted success in recovering the lost radio codes for their own radios.
 
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