by Jeremy Schrag • This unit appears to have been used by Dodge, Jeep, Chrysler, and Plymouth
In 1993 or so, Chrysler began to offer a CD playing head unit as a premium option on its vehicles. I have already looked at this head unit, known to many as the Infinity IV. It was a very expensive option at the time, available only with the name brand Infinity speaker systems. It was so expensive, in fact, that many people still opted for cassette decks in their new Mopars.
It was decided that a newer cassette deck should be offered as an option as well, for just those people. I am looking under the hood of that very deck today - the Infinity III. This is one that tends to fail frequently, and is commonly asked about on the forums.
The biggest difference between this deck and the Infinity II is in the styling. The faceplate got a newer, more ergonomic look with more rounded equalizer knobs and buttons that could be identified easier by touch. They were available in the black version seen here, and black with silver highlights for cars like the Fifth Avenue. This particular deck came from a 1993 Intrepid, due to my need at the time for a deck to drive my Imperial home with.
The supplier code for this deck is 28046, indicating Mitsubishi as the OEM. I have heard reports about some of these coming from supplier 7910 as well, which would be Huntsville Electronics (now Siemens), but have never seen one in person.
A pleasant addition to the sticker is the actual pinout diagram for the two main connectors on the back. Also present is a Mitsubishi model number: RX-695B.
Note the two screws visible near the connectors at the top of this picture. Any servicing needing to be done on this unit will require the top to come off at the very least. Remove the two screws to do just that.
Each side has two brass colored screws holding the faceplate on. I have indicated them with red arrows. You will also notice that there are two metal tabs beneath the black plastic under the screws. Remember those - they must be unclipped to remove the faceplate circuit board assembly.
It is not necessary to remove the fader knob to remove the faceplate, but you must remove the volume and equalizer knobs. The former is friction fit, the latter are snap fit. Just pull them all straight off.
The back of the deck shows us an 8 pin DIN connector. This is the exact same connector present on the Infinity II, used for the same purpose - to connect the single CD slave player or a factory optional changer. The pinout is the same as the Infinity II unit, so if you would like to use it as an auxiliary input, it is possible. Consult my guide to the Infinity II for the details.
Note that the factory changer that plugs into this connector is not the more recent one which requires changer controls on the deck itself. The Infinity III cannot run that changer. The one that will work with this deck has a separate control module; and was a dealer option, rather than a factory one. Be careful - the newer changer will still plug into this jack, and you don't want to do that.
This is the bottom of the deck. Red arrows point to the cassette module mounting screws. Don't remove those yet, but remember where they are.
Down at the bottom of the picture, you see two of the six black catches which hold the faceplate in place. Two on top, two on the bottom, one on each side. With the four brass colored screws removed, you can unclip and remove the faceplate.
Here, I've indicated in red a pair of twist tabs. These are used to hold the circuit board to the metal carrier. If you merely wish to replace bulbs, all but one can be replaced without ever touching these tabs if you remove the board and metal carrier as a unit.
At any rate, the board and the carrier must both be removed to work on the faceplate PCB at all. This is because the PCB is joined to the mainboard by wires that can only be accessed with half the deck taken apart. One way or another, you're taking the metal front off this thing. Let me show you how to do that.
This is the top of the deck with the cover removed. Four screws indicated in red hold the tuner module in. Blue arrows indicate the two connectors you have to disconnect to remove the module. One is a ribbon cable - be careful with it. There is a blue piece of plastic on these cables at the very end that holds the contacts in proper alignment. If that blue plastic comes off, it gets infinitely harder to reconnect that cable, because you have to straighten each wire at the end of the cable, align each precisely with the connector slot it goes in, and gently insert the wire hoping that none of those delicate wires bends and shorts out on the one next door. Then, you have to ever so gently re-insert the blue plastic into the connector on the side of the cable it's supposed to be on to hold the wires in place.
Ask me how I know this. Dealing with that blue plastic strip once it falls off is a nightmare I don't wish on my worst enemy.
With the tuner out, I'll show you how to service this module before we go on to the faceplate stuff. Red arrows indicate twist tabs - release them all, then turn the module over.
Red arrows here indicate some of the solder points that hold the board to the metal tray. Heat up the iron, and desolder those. Now, you should be able to get at the solder joints.
And this is where I tell you about the most common failure mode in these decks - bad solder joints. These decks are often riddled with them after all these years, even if they still work properly. This one was no different. Go through the whole tuner board, and touch up every suspicious joint you find. I found a lot of them. Then, put the board back in the tray the way it was.
Now, we'll take the faceplate PCB assembly off. Disconnect all three connectors indicated in red. Watch the blue strip on that ribbon cable again. While that ribbon cable can be disconnected at either end, it is by far easiest to do it down at the mainboard, rather than at the faceplate PCB.
Another view of the bottom, so you can keep track of the screws. The red ones are for the cassette module. The blue ones, shown already removed, are for the faceplate PCB assembly.
You should be able to unclip those four metal tabs on either side now, and gently work the assembly free of the rest of the unit.
If you're having trouble getting this thing out, note the red arrow. It points to the nut holding on the volume potentiometer and its own little circuit board. That little circuit board sits normally down inside a notch in the unit's mainboard, and can keep you from pulling this whole assembly off the unit. If that happens to you, just loosen that nut a few turns - just enough to wiggle it clear of that notch in the mainboard. The faceplate PCB assembly shouldn't fight you much beyond that point.
Once you do get this apart, a quick look at the back should show you several holes through which you can replace the faceplate bulbs. These are the usual 80s and 90s 12V grain of wheat microlamps with blue light filters on the front, found in most Chrysler decks of this vintage.
Here, I've released the two twist tabs and removed the PCB from the metal assembly to give you a better look. Note the gray lamp holder down in the bottom left corner - this is the one lamp that cannot be removed with the board still on the metal housing. All the rest are easily accessible.
Now, we're going to get even further into the deck. The mainboard itself often suffers from bad solder joints, so we'll need to remove it. The red arrow points to a screw - remove it. The teal arrows point to the connectors that run to the rear panel connectors - unplug them and make note of which of them went where. Remove the two screws on each side of the black and gray connectors, and remove these connectors from the back panel entirely. Disconnect the connectors indicated in yellow - these run to the tape deck.
Finally, remove all screws you can see on the back panel and remove the back panel. Some of these screws are longer than others - they hold the amplifier chips against the back panel for cooling. Make note of where they go so you can put them back later.
With the back panel off, we can clearly see the four amplifier chips in this deck - Hitachi HA13121's. These are the very same parts used in the Infinity II.
You should now be able to remove the mainboard.
Pay special attention to the area circled in yellow. See the discoloration there? The board has gotten very hot here, due to those resistors. You will likely need to re-solder everything in this area.
Here's the underside of the mainboard. Not a lot to say here, except heat up the iron and go nuts. Touch up anything that looks suspicious, and pay special attention to the areas arrowed in red. The bottom right corner is where we saw all that heat damage - you will probably have to hold the iron on these joints a bit longer than normal to get them to take solder properly again.
Also take note of the microlamp in the bottom center of the picture. This mounts in the same way as all the faceplate bulbs, and is the same type. It is there to light up the cassette slot.
To access the cassette module, there is a plate we must remove.
To do this, remove the screws indicated in red on either side, then lift the plate out. Try to remember how it goes back in... I would suggest taking a picture so you can tell easily.
From here, we see that the cassette module is nearly identical to that used in the Infinity II. As such, it shares the same flaws. The red arrow points to the loading mechanism cutoff switch - when the arm presses on it, the deck knows it has been ejected. Slop in this mechanism can lead to the deck never pressing on this switch hard enough, leading to endless cycling. There is a small tab there at the red arrow you can bend out slightly to help with that.
Note that while this module looks the same as the Infinity II mechanism, I cannot guarantee it is the same. The connectors and wires are not the same, so there is no simple plug and play swap between the two decks.
Once you remove the four screws holding the module to the bottom plate (refer to my earlier pictures of the bottom), you can get at the belts to replace them. Like the Infinity II, this deck also uses reel sensors to identify operation. If these fail, the deck will endlessly cycle the auto reverse until you hit the eject button.
Red arrows here indicate the two capstans. Give them a good cleaning, along with the playback head and pinch rollers, with rubbing alcohol before you put the deck back together.
We're all done. Let's put it all back together and test it out:
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