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by Jeremy Schrag
Not too long ago, a friend of mine who owns a car audio installation shop offered me the chance to show you something I'd have never been able to get my hands on otherwise. The end result of this conversation is the subject of my next two articles: the component audio system found in the 1991 Dodge Stealth and Mitsubishi GTO/3000GT.
Since the car was imported from Mitsubishi, it follows that the cassette and CD component system came out of the Mitsubishi factory as well. Since this wasn't your standard Chrysler product, the form factor of this component system also does not take on the familiar 1.5 DIN (which stands for Deutsches Institut für Normung) form factor. Instead, we have a pair of single DIN housings containing most parts of the system. In this respect, it is quite a lot like the component system we've already seen in the Eagle Premier system article, though newer and more complex thanks to the addition of the CD player.
Now, because of this CD player's presence, I will have to divide my disassembly efforts into two articles. This is because both components are quite complex and crammed full of electronics. We'll look at the upper unit today which handles the control, pre-amplification, tuner, and cassette duties. In the next article I'll show you the lower module which houses the CD player. The power amplifier is contained in yet another module that I don't have, and did not know existed until doing my research for this article.
In fact, the outboard power amplifier was only used in 1991 when it came to the Stealth. It may have been used in other models and configurations on the Mitsubishi side of things, however since this is a Mopar oriented website I will only be concentrating on the Dodge angle.
Our first stop in our tour of the upper module is this view of the top panel. There's not a lot interesting here save for three screws, which hold this top cover on. You will need Phillips #1 and #2 screwdrivers to work on this unit, though I found that my Torq-set #6 bit was slightly more grippy with many of these screws.
On the bottom cover, we find our label with all pertinent information. Of the screws seen here, the red arrowed ones hold the cover to the chassis, while the blue ones hold down the cassette module. Don't remove any of these yet... we'll be getting into this deck via the top cover.
Each side has but one screw we need pay attention to at this point. Arrowed in blue, they hold the faceplate on. The one indicated in yellow holds in a bracket that secures a daughterboard to the chassis. We'll get to that shortly.
On the back, with the bottom cover facing up, we see all six connectors for this unit as well as an insulated fuse holder for a 3 ampere fuse. Red arrows indicate the screws that hold the mainboard to the chassis, while blue screws hold the connector module to the chassis.
Unfortunately, I did not obtain any of the vehicle side harness connectors for these components, so I must infer the purposes of these connectors via some rather unhelpful wiring diagrams. The big white 10 pin connector is the amplifier output connector, while the six pin DIN connector on the far right is the amplifier input connector. The speakers do not directly connect to the amplifier module, rather all of its connections run through this module instead. We can call this the price of trying to cram too much functionality into too small a housing.
The five pin and nine pin black connectors to the right of the white connector are for speakers, power, and illumination. A round connector north-east of the fuse is for the usual Motorola antenna connector. Finally, the big square eight pin connector on the far left is for steering wheel remote control functionality.
Also listed in the wiring diagrams is an antenna interface cable which is apparently not present on my component set. Its purpose is to control the power antenna motor.
You will notice that there is a large cable coming out of the back of this unit as well on the left side. Terminating in an 8 pin DIN connector, this is the CD player interface cable.
Now that we've gotten all those connectors out of the way, we'll start taking things apart now. Remove the two screws holding the faceplate on, and remove the five equalizer slider knobs.
Keeping your thumb held lightly on the AM stereo button, pull the faceplate off. The AM stereo button is a creature unto itself, and is clipped onto the button switch behind it. If you don't do something to stop it, it will launch itself across the room when you attempt to remove the faceplate.
Note the positions of the foam padding behind the faceplate, just in case some of them fall off.
To remove the faceplate circuit board, one must now detach the friction fit ribbon cables arrowed in blue. Pull the top cover off to do that. Then, unscrew the red arrowed screws. From here, gently work the board up and out... there is a section of the board that runs back behind the LCD display. You will have to bend the board slightly to get it to clear that big white LCD housing. Be very gentle indeed... there is only so much force you can exert without snapping the board, and if that happens you have a whole other level of problems to worry about.
This is what the unit looks like with the board removed. Note the positioning of that black plastic insulator, in case it falls out. It must go back in properly.
I have also removed the shielded cover that goes over the equalizer sliders, to give you a better look at those. Make sure you clean those with contact cleaner, if they have been giving you static when you've tried to operate them.
The backside of the faceplate board. Note that while most components are surface mount, it is wise to go through and re-solder any bad joints you find. Being a vintage Mitsubishi product, bad solder joints aren't just likely but inevitable. I have not yet seen a Mitsubishi product of this age without them, after all this time.
Illumination bulbs are the usual 3mm 12 volt grain of wheat style bulbs, with yellow filters on them. On this part of the component system, they are all soldered directly to the board. Replace them all, if one has gone out, as the heat from your soldering iron will kill any marginally working ones there might be present.
Let's move on to the guts of this component, now. It's pretty jam-packed in there, isn't it? We're going to remove the cassette module next, but there are some other things to point out as well. Blue arrows indicate connectors for the daughterboards on either side of the unit. Red arrows indicate the brackets holding those boards in place... we have a black press-in bracket on the left and a metal screwed down bracket on the right.
Label all connectors so that you don't lose track of them. It's easy to do so in a deck this complicated.
Yellow arrows indicate the four cables that connect the cassette module to the rest of the deck. Before we can unplug those, we will have to turn the unit over and remove the four brass colored screws I arrowed in blue for you in my picture of the bottom cover. Holding the cassette module with your hand, carefully turn the unit over, unplug those four yellow arrowed cables as you gently lift the cassette module out, and then set it aside.
The cassette module. Does it look familiar? If not, it should... Mitsubishi was very fond of this mechanism in the late eighties and early nineties. Variants of it have been found in the Infinity II (both versions), the Infinity III, and even the Eagle Premier component system I mentioned earlier. It is a very troublesome mechanism, as I have mentioned before. Frequent issues include the tendency for the loading mechanism to develop slop in it, leading it to cycle constantly, erratic tape reversal behavior, and erratic 70uS detection.
The blue arrow indicates the arm where the loading mechanism presses on a switch. This switch is supposed to tell the deck that there's no cassette in the slot, but with the slop that can develop in the mechanism there is a little tab on this arm that may not be able to press on the switch far enough. I simply bend this tab so it's able to actuate the switch a little better.
The red arrow shows you the switch that enables 70uS detection, for metal and chromium dioxide (CrO2) cassettes. If the 70uS symbol keeps flashing on the display, clean this switch.
Make sure you clean both capstans, pinch rollers, and the tape playback head while you're at it. I use isopropyl alcohol on cotton swabs to do this. You may have to go through many of them, if the deck is especially dirty.
This is the other angle of the cassette module, so you can see the locations of the connectors. Unlike most of the Infinity decks I have had apart, this module is shielded and insulated behind the rear circuit board.
I've shown you how to swap the cassette belts on this transport mechanism before, but a reminder won't hurt. Disconnect the red arrowed ribbon cable - pull it straight up and out of the connector. Then, replace the belts.
Note the presence of the blue arrows - these indicate the reel sensors for the mechanism. If your deck is constantly auto-reversing, these have failed. They are not repairable and next to impossible to replace. If these have failed, it's time to look for a new module. I cannot promise that any of the other decks will be able to swap in, so it's best to try doing it only with an identical deck.
Now, we're going to pull those daughterboards out. Remove the brackets holding them in, then pull the modules straight up. The one on the left side of the deck will come right out. The one on the right has a ground wire that must be de-soldered first. I've indicated it in red.
Inspect both boards for bad solder joints and repair as needed.
Before we remove the bottom cover for access to the mainboard, there's a tiny little metal guard protecting the LCD connections from damage. It must be removed. Pry up on the clip arrowed in red, and pull it straight forward.
Now, remove the five screws holding the bottom cover on, then remove the bottom cover.
Repair any bad solder joints you find. As expected, I have found more than a few in this deck. I count more than fifty on this board alone.
Illumination for the LCD display is provided by grain of wheat bulbs in twist lock bases, indicated in yellow, much like you will find in nearly any early nineties Chrysler car stereo. This is a significant improvement on the Eagle Premier component set, which uses inline fuse style lamps impossible to source replacements for in 2013.
Again, these are 3mm lamps with yellow filters on them. To replace them, unwrap the leads from the twist lock bases and pull them out. You will need to re-use the bases, so don't let them wander off.
Our next step is to remove the connector module. Refer back to my image of the back panel and remove the blue arrowed screws. The module will come straight out the top.
Again, inspect the underside for bad solder joints.
Our very last image is of the mainboard from above. You may remove it, if you wish, by disengaging and de-soldering the twist tabs underneath, and de-soldering the red arrowed ground straps, but this is not necessary for 99% of the repairs you would ever need to do to this board. I have elected to not bother for this article, as only the AM stereo daughterboard, located in the top center, is not accessible from here.
That's all for the cassette, control, and pre-amp module of this highly sophisticated component system. Now, explore the CD module and see what makes it tick. One day I hope to uncover the amplifier module as well, but as the Stealth is a rare vehicle in the boneyards around these parts I am not getting my hopes up.
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