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Factory Quartz Lock Stereos of the 1980s

by Jeremy Schrag

In my last article, I had a look at a mid 80's Audiovox build Quartz Lock head unit; intended to be a dealer option for Mopar vehicles. At the end of that article, I promised that I would dig into another Quartz Lock model, this time a factory original unit. The time has come.

The unit I'm going to write about today is by no means the only Quartz Lock model you could get as a factory option. There were quite a few different units over the years that came in both black and silver faces. However, today's example is probably the best of the whole lot in terms of audio fidelity. It is a more recent model that came from a 1986 vehicle.

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One of the main ways this unit is different from some of the other Quartz Lock models is that there is no local or distant search button on the face. There are six radio preset buttons, but no set button. Since operating instructions for this deck are somewhat hard to come by lately, I'll give you a few tips on the less obvious operating modes of this deck. To set the clock, hold any preset button until the letter "P" shows in the display. Then, press the volume knob, and use the tuning knob to set hours. Press the volume knob again to set minutes. Press it a third time to exit clock setting mode.

Storing a radio preset is actually quite easy. Simply tune your desired station, and then press and hold the preset button you want to store it in. This is the same method used to this day by many aftermarket decks to store presets. On this deck, you can store six presets each for AM and FM, a little bit of a step backward from some other Quartz Lock models that have a set button, and allow for more than one station per button to be programmed.

Dolby noise reduction, common on some of these decks, has been removed in favor of National Semiconductor's more generic in operation "DNR," or Dynamic Noise Reduction. The difference between the two is, Dolby's system requires the source to be encoded. DNR does not, and will work on FM broadcasts as well as cassettes. Back in the 80's, neither system was really ideal for an automotive environment, where thanks to road and wind noise; enabling the noise reduction usually resulted in most of your treble going away.

Speaking of treble, there is another difference in this deck compared to some others in the Quartz Lock name... this model actually has separate bass and treble controls around the volume knob, instead of a single "tone" control. There are therefore three parts to this potentiometer - the volume knob in front, the knurled bass knob in the middle, and the thin treble ring at the very back.

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As I usually do, I'll show you how to take this unit apart. This model is quite a bit easier to deal with than the Audiovox dealer option, so this will go a lot easier for you. I've labeled the relevant screws above: A - faceplate mounting screws. B - cassette plate mounting screws. All front panel knobs are friction fit and will have to come off to remove the face. The balance knob only needs to be removed if you are replacing a burned out illumination bulb.

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There are some more labeled things to tell you about here: A - top panel screw. This is the only screw that holds the top panel on. With it removed, you can just pull it up and off.

B indicates two more of the cassette tray mounting screws. There are four in total. C is the ground strap bolt, which will also have to come out to access the cassette assembly.

Red arrows indicate the four rivets that hold the two amplifier chips to the rear heatsink. They will have to be drilled out if those parts need to be replaced.

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Here's the other side before we get any further. As was the case before, the A screws are for the faceplate and the B screw is the final cassette tray screw. These all require a 1/4" nut driver or socket to remove.


The top panel from above shows us a rather Swiss cheese looking view. There is an insulator below this panel that must be replaced as it came out - with all the holes lining up with those in the top panel.

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The bottom panel. All screws visible, indicated in red, are for mounting the cassette mechanism to the cassette tray.

In the middle of the bottom panel is some glue residue from where the part number sticker used to be. I do not recall the part number, but I do know that this deck came from supplier 7910, or Huntsville Electronics (now Siemens).


Let's start taking things apart. After removing the knobs and the four faceplate screws, pull it gently away from the deck. As you can see here, there is a connector to undo. There is no latch on this connector... just pull it right off.

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It's time I showed you how to service the button switches and illumination bulbs on this unit. You will need to remove both circuit boards. A blue arrow indicates the board for the eject and noise reduction buttons. This will be glued in, and probably not very well after all these years. The green arrow indicates the illumination bulb socket for the buttons on that side. It is empty in this picture.

Red arrows indicate the four catches that hold the main button board in. Release them and work the board up and out.

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On the left is the main button board. You will notice a button switch is missing - I've used this deck as a source of parts for the digital cluster in a 1988 New Yorker. Yes, the button switches are exactly the same.

In the upper left are two more bulb sockets. All three illumination bulbs are #74. These should still be rather easy to find at your local parts store, as they are pretty widely used.

Cleaning the button switches is possible, but a little difficult. Usually, after all this time, the rubber contacts in these have all gone hard and broken to the point that they no longer have any spring to them. Every button switch in this deck has gone soft and spongy due to these broken contacts.

Now, the plunger assembly is merely snapped into the main body of the switch. Take your needle nose pliers and gently work the plunger up and out.

Here is an extreme close-up of one of the button switches. As you can see, the black contact has a little piece sticking up in the middle. This is the part that's supposed to provide the springing action. It's canted to the side here, indicating that it is broken. These will usually still work as such, but may need cleaning.

In this picture, the black contact is actually oriented with the wrong side up. When installed in the switch, the broken springy part faces down. The contact itself is the circular rim. To clean these, all you really need is a pencil eraser... just lightly scrub around that rim. The contacts inside the main housing will need to be done too. The easiest way to do that, I find, is to cut a small piece of pencil eraser, stick it on the end of a flat bladed jeweler's screwdriver, and then gently scrub the metal contacts inside the housing. The housing is too small to let the end of a pencil in there, otherwise.

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Now we will turn our attention to the main body of the unit. Remove the screw holding the top panel on, and remove the top panel.

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Here's the insulator - make note of where the holes go.

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With the insulator removed, we can now access the tuner board in this deck. At this time, if all you want to do is touch up the solder joints in here, you can stop right here and get it all done without taking either this board or the mainboard out. Indeed, the mainboard cannot even be removed without drilling out the rivets holding in the amp chips. Fortunately, the mainboard does not need removing either to access its solder joints.

If you do need to remove the tuner board to replace parts on either the mainboard or tuner board, you may do so by removing the screw indicated in blue. Then, de-solder and unbend the tabs indicated in red.

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The tuner board will come out like so: lift up and pull forward. Note the connector arrowed in red - you will probably find yourself having to push gently on this to get it to line up again when you go to put the deck back together.

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Here's the tuner board.

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Now, a look at the mainboard. The red arrows indicate the amp chips, labeled as Toshiba 3341's. Here, you can also access the potentiometers to clean them.

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Removing the cassette tray is very easy. Just remove the four screws and ground strap bolt I showed you earlier, lift up at the back, and pull it off. As you do, be gentle - there is a connector to the mainboard you will need to unplug.

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That connector is indicated in red, here. Unplug that, and you can set the cassette tray aside.

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There is another insulator to deal with if you need to do any soldering on the mainboard. It is held in using a plastic press fit pin arrowed in red. Pull it out, and pull the insulator out.

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While this deck has some differences with other Quartz Lock decks, the cassette deck is not among those differences. Most of these decks used this very mechanism, apparently sourced from Mitsubishi. I will remove the three mounting screws and show you how to get at the tape belt.

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Replacing the belt is incredibly easy on this mechanism. All you do is remove the three screws arrowed in red, pull the retaining plate off, and you can replace the belt. Be careful not to turn this over after you remove that plate - it is all that is holding the capstan reels in place, and they will sometimes try to fall out.

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The mechanism with the plate removed, showing you how to route your new belt if you got in there and found it broken.

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As is the case with all auto reverse decks, this one has dual capstans to clean. The arrow points to one. The other one is actually easier to get at from up top than from here, while the tape head is buried way back in there. Use cotton swabs moistened with rubbing alcohol to clean the capstans, head, and pinch rollers.

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Here's a look at the top, with a red arrow pointing at the rear capstan and pinch roller. It's very easy to clean from this angle.

So ends my article on this particular Quartz Lock deck. Most of them are quite similar in how they are put together, so this article should be of assistance to the majority of you who need to get one of these apart. Next time, I'll look at the Infinity I deck and tell you all about the oddball RJ45 jack only found on that particular deck.

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