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Discussion Starter #1
Greetings, electronics people!

I have a Chrysler Infinity IV radio, supplier code 26777. It features an analog 5-band graphic equalizer, internal CD player, detented rotary encoder volume control, and the balance/fader joystick has a slighty-wider-than-high rectangular faceplate.
As I understand, these units were made by Alpine.

Two things:

#1 - The VFD (Vacuum Fluorescent Display) on this radio is completely dark/blank. I heard this was a common problem with the Infinity IV radios, but I was unable to find an exact "likely cause". People on other sites and forums were saying "Just get an aftermarket radio", but that's not an option for me. I'd much prefer disassembling this radio, finding the fault, and soldering/desoldering the defective part or broken circuit board track or whatever. (Unless of course the VFD has developed a leak and lost its vacuum, or its internal heater/cathodes have burned out; in that case, I'll be looking for another Chrysler radio.)

#2 - I'd like to add an analog auxiliary line input to the radio. Unlike the older radios with potentiometer volume controls (which were almost always fed more-or-less at the de-facto standard -10dBV line level), this is a little more challenging. I need to find an analog stereo line level signal that I can intercept, pre-volume, pre-equalizer, pre-balance, and obviously pre-fader. Is anyone familiar with these radios who can possibly save me some "reverse-engineering" time with this? I already discovered the radio uses a pair of Mitsubishi M5227 chips for the analog EQ (one chip for left channel, the other for right channel), so I was going to start tracing back from their input. But tracing the high-density multi-layer circuit board is rather tedious, and even if the M5227 is the first processor on the audio signal chain, I'd rather tap into the radio's main boards (if possible) instead of the faceplate circuit board. So if someone already knows a good place to tap into the audio signal chain, receiving their wisdom would be wonderful. :)


And one final thought: The radio has a 2-pin connector (male socket) on the back, but no label as to what it is or what it does. Is this an external audio input? Because if so, that makes my work on this project much easier! :lol: (I know one of the 7-pin connectors on the back has a "MUTE" pin.)

Thanks.
 

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A 2 pin connector is most likely for steering wheel mounted controls.
 

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1 - usually an SMD resistor that has been too hot for too long and has de-soldered itself from the board. Look on the top PCB near the rear left of the unit - this will be a large SMD resistor, probably at the center of a discolored area on the board.

2 - good luck with that one. Haven't really seen anyone pull it off successfully. Schematics aren't available, so you'd be on your own there.

The two pin connector is a CCD bus interface for steering wheel control, diagnostics, and display dimming info for those vehicles that have a switch to brighten the vehicle displays when the headlights are on. Not related to the current display issue... these function fine without this connector plugged in.
 

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Discussion Starter #4
Thanks. I'll take another look at the Infinity IV boards soon.


Re. aux audio input, I did this twice:

...Once to an old GM radio, I'm guessing from the early 1970's, or maybe even late 1960's? (It had FM, but the thing was mono. It used a single power transistor to drive the speaker, and a giant choke to take advantage of its back-EMF for the reverse-polarity voltage swings.)

...And once again to an AM/FM stereo Chrysler radio yanked from my parents' old 1979 Dodge 024 Omni.

In both cases, the volume potentiometers were connected to the circuit board via fly-wires (no direct soldering), so adding the auxiliary input was as simple as desoldering these wires from the "top-end" of the potentiometers, and running my aux in wires to the potentiometers instead.
 

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If you are still looking for the dead display solution, I have had the same problem and found the answer on the internet. It is a surface mount resistor that needs to be re-soldered. I'm currently opening the same radio to repair a bad audio power amp. If you need more info on the surface mount resistor, I could take a close up photos of the resistor and post them.
 

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If anyone has made any progress in adding a AUX AUDIO INPUT to the Infinity IV made by Alpine, please post your information. I'm researching the design of the radio to see if this can be achived. The speaker connector has a mute input pin that is unused. Placing a 1K ohm resistor from this pin to ground will mute the audio. I think the audio multiplexer function is performed by the Alpine IC on the power amp board. I will start by probing the pins on this chip with my oscilloscope. It would be nice if someone had a pinout diagram for the Alpine IC.
 

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Hello all. I stumbled across this site while looking for repair info on my CD drive. I have figured out the Aux Jack solution for these radios. Contact me by my username at gmail for info and pictures as I don't know how often I will frequent this site.

Does anyone know how to repiar the CD drive? It will not accept CD's. There is a problem with the loader. When you power the radio on it will run for a few seconds then turn off. There seems to be in issue with the solenoid that engages the gear to move the loader tray.
 
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