by Jeremy Schrag
Today, I'm looking at one of the most common head units to have ever been offered by Chrysler in Dodge and Plymouth cars. Found in many vehicles starting in the mid eighties, the above AM/FM cassette deck was most commonly used in cars whose owners didn't want to spring for either the Infinity audio system, or even the premium non-Infinity decks of the day. Indeed, several vehicles equipped with these economy cassette units didn't even get Infinity as an option.
Back in the day, when my parents' 1993 Caravan Infinity IV deck failed, this one took over as a loaner deck for a week while the dealer sent the CD player out for repairs. In other words, this was the deck you got when you wanted something from the factory with a cassette deck as cheaply as possible. Consequently, there are a lot of them out there. This particular one came out of an early Dynasty, and I'm going to show you how to service it.
As you are about to find out, this deck isn't that complicated to work on, but there are a few tricks here and there to be remembered.
On each side of the deck, there are two screws. These must be removed to pull the faceplate off. We'll get to that momentarily.
This is the top panel of the unit. While there are no screws up here to remember for later, there are several solder tabs we will need to keep in mind. More on those later.
First, take a look at the label of the unit. This fell off the deck as I was removing it from the donor vehicle. The part number is 5269414, while the supplier code of 7910 indicates Chrysler's Huntsville Electronics as the maker.
This is the bottom of the deck. The four screws you see here are for the cassette module. Remember those for later.
The back panel, with the usual black and gray connectors. Note the arrows - red indicates the screws holding the cassette tray to the deck, while blue arrows indicate the screws for the amplifier chip clip.
Most screws in this deck are Torx in T15 and T10 sizes, while a few are Phillips.
Let's remove the faceplate now. Take out the four T-15 screws on the sides of the deck. Remove the volume, tuning, balance, and fader knobs. They are friction fit, but may fight you a bit. Then, pry under the black plastic in the center of the top and bottom to release the catches. The faceplate should now pull away.
I've hinged the faceplate up on top of the deck to show you how it's held to the deck. As you can see, there is one friction fit connector (white) joining it to the rest of the circuitry.
A ground wire, held on with a single T-15 (shown with a red arrow), will need to be removed to completely detach the faceplate.
In order to do any work on the faceplate PCB (printed circuit board), several catches will need to be released. I've indicated them in yellow. Be careful with those, and have patience while releasing them. I find it easiest to start in the bottom right area of the picture, and work my way up and left. The ones on the sides in particular will fight you hard - you must gently pry on those with a screwdriver to release them, and if you apply too much pressure you will damage the PCB.
Note the red arrows. This deck uses a big power resistor that gets rather warm in operation. It's a good idea to re-solder both of these indicated solder pads while you're in here. Mine looks to be well soldered yet, but enough heat over enough time may cause these joints to let go.
A look at the PCB from the other side. Again, the power resistor is indicated in red. The discoloration on the PCB in this area gives you an indication of how much this area has been baked over the years.
I have also removed one of the microlamps and placed in the cassette hole for your inspection. These are the usual 3mm 12V grain of wheat bulbs used in most 80s and 90s Mopar decks. The button switches are self contained, and it should not be necessary to service them. In fact, you should not need to remove this entire PCB unless you are making board level repairs to the components you see here. The illumination microlamps can be replaced without going to this much trouble.
Now, we'll get even more into the unit. You can skip this step if all you want to do is work on the cassette deck. In order to do anything with the mainboard and daughterboard inside the unit, the two parts of the main case must be separated.
On the back panel, remove the two T-15 screws holding the cassette tray to the main unit. Then, if you are also looking to work on the mainboard, remove the T-10 screws holding the amp chip clip to the back panel.
Then, observe the above picture. Pull the thick outer shell in the direction of the red arrow. Then, hinge this piece away from the inner section, as indicated by the blue arrow. Once done, remove the outer shell by disengaging the pivots on either side.
I've shown one of the slots for the outer shell pivot points here in red. There's a matching one on the other side.
Now, on to the cassette tray removal. Remove the nuts arrowed in blue, then pull the cassette tray forward and out.
The cassette section is joined to the mainboard via the connector indicated in red. Disconnect it.
Before we get to the tape deck, let's work on the mainboard. It is secured via twist tabs (red arrows), solder pads, and the black and gray connectors on the back. There are two part numbers printed on the mainboard - one for cassette, one for no cassette. It is likely that the board is shared with one of Chrysler's tuner only decks.
Blue arrows indicate the catches for the black and gray connectors. What you need to do first is pull them right off the back panel. Then, de-solder the pads underneath... I'll show you those in a second. Finally, release the twist tabs so you can pull the two boards out.
Here, I've shown the black connector already removed to show you how those work. Don't worry, you cannot mix them up - they only go back onto the deck one way.
The red arrow indicates the amplifier chip. Mine is lacking any thermal grease - it's a good idea to put some on while you're here.
Here's the top panel again, without the tape that was on it. Red arrows indicate the solder tabs for the mainboard.
The mainboard and daughterboard have been removed. They are married to each other using a ribbon cable that has no connectors on it, so you cannot remove one without the other.
Look for and repair any cold solder joints you see. There aren't too many that I can see here, but there are one or two here and there. After decades in a vehicle, bad solder joints are almost inevitable.
This is the amp chip up close. It is a Philips brand unit, but uses a Chrysler part number. It should still be possible to find replacements, though it may be difficult.
Let's get into the cassette deck now. There's a trick to removing this.
First, you must detach the circuit board. Remove the screw arrowed in red. Then, slide the board in the direction of the blue arrow until the catches indicated in yellow release. Pull the board away from those catches... it is now free to come out with the rest of the module.
I've moved the board up and out of the way so you can see its mounting points a little better. While one might initially think these two brackets must be removed to remove the module, this is not the case. It's a good thing, too - the bracket mounting screws are nearly impossible to access without removing the board first.
Now, remove the four screws underneath that hold the mechanism to the tray, and lift the mechanism and board out as a unit.
From here, we can easily replace the cassette belt. There is no need to get any further into the mechanism than this - the belt is just right there as soon as the mechanism comes out.
Finally, we'll clean the capstans and tape head. I've indicated the capstans in red, here.
We're all done for today. Do you remember how to put this unit back together?
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