Here is an instruction to add your own audio input to an Alpine CM1910 from an R170. I performed this upgrade to the MB stereo in my '01 SLK 230 over a year ago. The pictures were so annoyingly fuzzy I had not planned on publishing; however, was PM'd asking for details. I've not done enough posts to PM, so here it is for everyone. (yeah, i know, welcome a dozen or so new members and i can pm; i'll do that one day)
- This mod does require an empty cassette in place to keep the audio flowing.
- Find an old earbud cord and snipped off the ear ends.
- Salvaged a pair of 1000 ohm resistors from your spare parts bin.
- You will need a couple of screwdrivers and a fine tip soldering iron.
- Red markings in pictures note areas of interest.
1. Remove the metal top cover from stereo receiver head unit.
2. Remove cassette drive unit. Thread the new audio cord through any convenient opening. The circuit board on back end of cassette drive is where connection is made.
3. Picture is looking at the circuit board on the back of the cassette drive unit. Note the left 3 soldered pins starting a uniform row near the top of the board. These are left, right, and ground for the audio input connection.
4. Cable-tie the audio cable to a metal hole on the lower left corner for strain relief. Put a couple layers of electrical tape over the circuit board between the cable-tie and the 3 pins of interest. Solder a 1000 ohm resistor between the pin I marked "L" and one of the audio wires of the cable. Solder a 1000 ohm resistor between the pin I marked "R" and the other audio wire of the cable. Solder a wire from the pin I marked "G" to the shield wire (i.e. ground wire) of the audio cable. Carefully add some electrical tape to ensure no uninsulated wires touch anything.
5. Return the cassette drive unit into the stereo assembly using caution not to pinch the audio cable. Replace the metal cover.
6. Happy listening!