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by Jeremy Schrag
Back in the early 1980s, cars began to suffer from what I like to call the "Knight Rider Effect." Buttons and digital displays appeared and reproduced like rabbits on the dashboards of most auto makers, and things quickly progressed to the point that cars even started to talk to us.
When the 80's really got going, Chrysler decided that to remain competitive, they should get as button happy as the other manufacturers. Their audio systems were the first place to show signs of this, and it wasn't long before electronic tuning showed up as part of the more expensive options available at the time. And then, in 1982, the infamous Quartz Lock decks appeared. Featuring both electronic tuning and auto reverse cassette decks, these were quite expensive decks in their day. And that posed a problem for buyers. What if the cost of the stereo was too high at the time of purchase for them? Many people back then couldn't see their way to spending hundreds on a cassette player, especially a fancy schmancy one with a digital tuner. But they could see themselves buying the car now, and buying a tape deck later.
Enter the "dealer option." Many dealers back then offered an expanded selection of head units intended to look good in the dashboards of Mopar vehicles. Commonly built by Audiovox, these were units that offered owners the fancy features they wanted without having to go further than the nearest dealer to get them.
It is one of these somewhat uncommon dealer option units I am looking at today - the Audiovox Quartz Lock Special Performance Series.
This particular deck came out of a salvage yard, found in the dashboard of a Caravelle. It bears some resemblance to the earliest official Quartz Lock decks in that there is a double row of four small buttons above the AM/FM button, but unlike those decks there is no "dis" button, short for distance. There is, however, a local button, used to tell the tuner to seek out only strong stations when using the seek and scan functions.
All other buttons are mostly self explanatory, except for the "pro" button. This one stands for "program" - it activates the auto reverse function on the tape deck.
Here's the top of the deck, and the closest thing to an Audiovox part number as we are going to find on the unit: 86-CP-DGC/S. Note that there are no screws holding the top on... it is actually quite easy to remove. I'll get into that later.
The left side.
And the right side. There are three screws holding the faceplate on... after pulling the knobs off the front controls, the faceplate is merely clipped on. With these three screws removed, both the faceplate and the top/back panel can be removed without further use of tools.
Here's the back of the unit. Unlike most newer Mopar decks, the black and gray connectors are attached to a harness that runs into the deck. The same approach is used for the antenna jack.
There is no ground bolt on this unit, either. Grounding is provided by a separate black wire coming out of the harness. You can see it here terminating in a blue butt connector.
I've pulled off the faceplate here. Red arrows indicate the screws that hold the faceplate PCB to the rest of the deck. You will have to remove these if you wish to do any work that requires removal of the mainboard.
A red arrow here shows you how to remove the top and back panel. Two tabs hold it in down where the wires come out of the deck - simply hinge it back like so and remove it.
Now is when things get really complicated. This deck requires a lot of de-soldering work to get inside it. Start by de-soldering the yellow indicated ground wire. Then, remove the screw indicated by the blue arrow, and let that little circuit board hang loose.
Then, see the red arrows. A metal tab on each side holds these wires in place. Bend them and move the wires to the side so you can work on removing the mainboard.
Things are going to get crazy from here on out. See the tan shield in the middle of the picture? This is soldered down, and should be removed to facilitate removal of the front panel PCB. De-solder the tabs indicated by cyan arrows to do this.
Blue arrows indicate screws that should be removed. Do so. Then, de-solder and bend the tabs indicated in red so that you can remove the mainboard. There are ground wires attached to two of these tabs - note where they go, because they will come off once you remove the solder from the tabs.
It gets really hairy from here. As you can see, I've circled a long row of solder joints in purple. To remove the faceplate PCB, which is necessary to remove the mainboard, every single one of these must be de-soldered. Take your time - patience is a virtue on a job like this. The display leads in the center are particularly trying - I found it easiest to lift upwards on them with a dental pick while touching the soldering iron to each joint to free them up.
There's a trick to re-soldering the 90 degree solder joints I'd like to tell you about now, before we go any further. With the mainboard facing the sky, you basically take your hot iron and aim it straight down at the circuit board. Touch it down on the mainboard trace you plan to solder perhaps a millimeter away from the faceplate PCB. Apply a generous bit of solder to the mainboard trace. Now, slide the iron slowly along the trace up to the faceplate board, and then drag the tip of the iron up along the faceplate PCB trace corresponding to the mainboard trace you're soldering to. This should leave a perfect 90 degree joint. Take care that you use an iron with a fine point - four of these traces are quite small.
I know, I know. Why didn't they just use wires and connectors, instead of these time consuming 90 degree solder joints? Beats me.
You should be able to remove the faceplate PCB now, and we can finally get the mainboard out. Loosen up the blue indicated nuts holding the volume and tuning pots in place, just far enough to pull the locking clips forward to release them. These potentiometers will slide up and out of those vertical slots along with the mainboard now.
Here's the mainboard. Tuner daughterboards on the left, amplifier daughterboard on the right. I aim to show you what's under that metal shield, so I might as well tell you how to remove this as well. De-solder the ground wire indicated in red.
Then, de-solder the tabs indicated in blue. These are the same tabs the tan colored upper shield solder to. The shield should pop off now.
The parts under the shield include the LC6502C microcomputer that controls the deck, an LB1290 chip used to drive the digital display, and the LM7000 tuner chip. Immediately to the left of the LM7000, you will see the crystal that gives rise to the name "Quartz Lock." Basically, a quartz crystal is used to lock in your desired stations.
The four tuner daughterboards up close. I won't get too far into this part of the deck.
But I will, however, remove the amplifier daughterboard. This is where you are most likely to find problems with solder joints in this deck. You do not have to remove the board to touch up all the joints, I have only done so to give you a better look at the whole assembly.
Most of these joints were found to be in rather poor shape, especially around the jumper wires that join the daughterboard to the mainboard.
Here, I've removed the heatsink and clips from the amplifier chips. If you do have the deck this far apart, it is wise to apply new thermal grease to the heatsink.
Two of these chips are used for amplification - they are NEC uPC1230H2 parts. If that sounds familiar, it could be because you just read my guide on repairing Chrysler/Infinity speaker amplifiers. This deck uses the very same amp chips those speakers do. They will do roughly 20 watts in total, or 10 watts per channel in dual channel use. This deck has two of these chips each driving two channels, so the whole deck is good for roughly 40 watts in total power output with 10% THD, 13.2 volts in. Not too bad for an early 80's deck, but this is not exactly the most powerful deck Chrysler used in the 80's. That honor goes to the Ultimate Sound based decks, including the Infinity II, which used four Hitachi 15W amp chips per unit.
It's time to have a look at the cassette deck in this beast. But first, have yourself a look at the big metal shelf with holes attached to the case on the right side of the picture. This is where the amplifier heatsink is - the idea is for the amplifier heatsink to meet this big metal piece and get even more heatsinking for the amp chips. This deck has no thermal grease applied to this area, but it is not a bad idea to put some there before you put the deck back together.
The cassette deck is held down with four screws. Remove them, and then remove the tape deck.
The business end of the tape deck. This is actually quite a simple mechanism for an auto reverse. The tape head, capstans, and pinch rollers are probably easier to access on this deck than any other Chrysler deck I've seen.
Blue arrows indicate the pinch rollers and capstans, red arrow shows you the playback head. Clean them all up real good with some isopropyl alcohol so the deck won't eat your tapes.
Underneath, a plate held on with four screws hides this view from you. Now, we will gain access to the tape belt. In another "what were they thinking" move, Audiovox has designed this deck so that you must remove that green flexible PCB in the center of the picture to get at the belt. This PCB houses a single switch up at the top and two reel sensors. Remove the screws indicated in red, and de-solder the row of joints indicated in blue.
You should be able to pop off that little PCB now and replace the belt.
All done? Go ahead and put the deck back together. Make sure you go over all circuit boards carefully, looking for bad solder joints, as you re-assemble the unit. This is one of those "don't want to do this twice" jobs, especially when you're dealing with the faceplate PCB solder joints.
You should now have a working deck. I... do not. Unfortunately, this particular deck is too far gone for me to bother fixing. I got it to show me the clock, and that's all it does other than light up the front panel illumination. No tuner, no cassette, no sound.
Next time I'll look at another Quartz Lock deck from a somewhat more recent vintage than this one - an actual factory original unit.
Chrysler 1904-2018 •
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