by Jeremy Schrag • This unit appears to have been used by Dodge, Jeep, Chrysler, and Plymouth
Today, we continue to explore Chrysler's early entries into the premium audio arena with a look at the Infinity I head unit. This is not the first deck to bear the Infinity logo on the faceplate, that honor goes to one of the Ultimate Sound decks from 1987, but it is the first deck to start being known in general among owners by the name Infinity.
Starting about 1988 or so, this was the entry level deck you got when you specified the Infinity option on many 1988 Chrysler vehicles. This particular one came from an early Caravan. Some features included an auto reverse tape deck, AM stereo, and buttons upon buttons upon buttons. Indeed, there isn't much on this deck not controlled by buttons or toggles. [Editor’s note: in that regard, it presaged modern decks, which often have one knob — if that.]
There are a number of different versions of this deck out there, both in silver highlights and all black, but most of them are fairly similar in both look and operation. You could even find this deck as a premium unit without the Infinity logo on the front, and this guide applies to those models as well. The only meaningful difference I've found between the Infinity and premium models is the presence of the slave CD connector on the back.
As always, the label tells us who made this unit via the supplier code: Huntsville Electronics.
Before we start the disassembly, I did have some success in finding a service manual for these units. It can be found around the Internet for the Googling.
First things first, we need to remove the faceplate. Like some others from supplier 7910, getting inside this deck is quite straightforward. First, remove the faceplate by removing the four Torx T-20 screws on either side.
You can see another screw in this shot - there is a matching one on the other side. I'll show you what those are for a little later on.
Meantime, I want to show you the back panel for a moment. We have the usual black and gray connectors for the main harness, but we also have two other connectors. One's an RJ45 and the other is an 8 pin DIN connector. The DIN connector is for the slave CD deck that was optional starting in 1988. But the RJ45? That's always been a mystery. No other Chrysler deck has this connector, and there is no data on the internet as to what the pinout is. Some have speculated that it is for the visor phone - a dealer only option.
The mystery about this connector ends now, folks. I have the service manual, and therefore I have...
Now, then. Before we go on, I've drawn some arrows in the above picture to highlight some important screws. Yellow holds on the cassette tray, along with the four front panel screws. This means once you have the front panel off, all you need to do is remove these two screws to pull the whole assembly apart. Red arrows indicate the top panel screws. Finally, the blue arrowed screws hold the amp chips to the case. There are four of them - two on the back and one on each side. You saw those other two earlier.
Here's a look at the underside before we go on. Those four screws hold the tape mechanism to the tray. We'll get to those later.
First, we'll take the faceplate off. Note the two metal clips on either side of the faceplate. These aren't essential, but they do keep you from cracking the plastic with over tightened screws. You will need to remove these clips if you wish to remove the faceplate circuit board.
Unplug that long connector by just pulling it forward, and you can remove the faceplate.
Red arrows indicate the illumination bulbs. These can be removed with a small slotted screwdriver. Turn them about a quarter turn counter-clockwise, and they will lift off the board. Perhaps with a bit of coaxing.
Yellow arrows indicate the clips that are holding the circuit board in. There are no screws - just unclip and wiggle the board out.
A close-up of one of the micro lamps used in this deck is on the right. These are very popular among most 1980s and 90s decks, and by now most of them are as likely as not to be burned out. You can replace these, but you must save the twist-lock base. What you need to do is, unwind the leads from the base. Then pull the bulb out of the base, and remove the blue filter.
Finding replacements can be a challenge, so I'll tell you what to look for. You need 12 volt "grain of wheat" bulbs. They come in many sizes - you want 3mm. These are popular in the model train world, so try a local hobby store if you can't get them at an electronics store. eBay is also another good source, where you can even find the blue filters (among other colors) in case you damaged one. You can even get these in blue without needing the filters at all. Once you have them, just put them back in the base and wind the leads back the way they were.
A look at the business side of the faceplate board. Each button switch has a long, clear plunger to help with the illumination. Be careful putting this board back in the faceplate - those plungers need to drop straight down into the buttons.
A close-up of the fader joystick. There are two potentiometers on this assembly... you may need to clean these if they've gone scratchy. Observe the green arrows and the holes they point to - just shoot some contact cleaner into these holes and work the joystick for a bit. Repeat this once or twice. That should clear up the scratchiness.
Now, we'll get into the deck proper. Remove the top panel, and you will see this insulator. Note where the holes go, and remove it.
We'll now remove the tuner board. De-solder the tabs indicated in red, and bend the tabs out of the way. Then, pull the board up where the black and gray connectors are to unplug the board to board connector inside.
I've indicated both parts of the board to board connector in red, here. This really is an easy board to remove, though this connector may prove to be tight. Just wiggle the board back and forth in the corners until it pops the connector loose.
Here's the view of the insides from above. You can see two part numbers near the top middle - one for Infinity, and one for premium. The mainboard is the same for both; differing only in the presence of that slave CD connector.
Now, you can remove the mainboard if you wish, but unless one of the amp chips is fried this should not be necessary. Re-soldering bad joints can be done without disturbing the board itself.
Now, we'll remove the cassette tray and front panel. Remove the two screws on the back panel and separate the two pieces like so.
We now have one connector to unplug, and here it is. Pull it straight out. Don't worry - it is keyed to prevent it going back in the wrong way.
I'll show you how to remove the mainboard to replace amp chips. First, the black and gray connectors need to be pushed out. Depress the two catches on either side of each connector and just push on them. They should come out easily. Remove the big ground bolt in the lower center so that you can get at the amp chip retaining screw it's blocking.
You may be asking what the deal is with that spade connector ring on that bolt. Well, that's for the Infinity amp and antenna relay. It grounds the relay coil, enabling the power antenna feed wire to turn on the Infinity amplifiers.
Another look at the side panel. The blue arrow is, once again, an amp chip retaining screw. You need a Torx T-15 to remove all four of these.
Red arrows indicate some important holes. Let's go to the next picture for a second.
See the red arrows here? Those tabs are holding in the mainboard. You need to de-solder and push these into the side of the housing to slide down and remove the mainboard.
But how do you bend them back out again to re-solder them? That's when you go back to those holes in the previous picture. Poke a screwdriver through these, and you find that they are there to help you bend those tabs back into place. Very thoughtful. And all five solder tabs have these holes.
Here's the mainboard removed. Red arrows indicate the little metal indents the board rests on. When replaced, this board must seat between these indents and the solder tabs. It's not too hard to get the board back in there, but you may need to flex the sides of the housing to do it. Don't forget to loosen or remove the amp chip retaining screws first.
Here is one of the four amp chips. I could not locate any data on these, so your best bet might be to grab another deck like this for parts if you need to replace one. It is not a bad idea to re-solder all the pins on these before you put things back together. These are some of the major heat producing parts, so they are the most likely to have bad joints.
Now, we'll get a look at the tape deck. Note the screws pointed at in red - these hold the plastic shroud over the assembly. You may need to remove this to clean the rear pinch roller and capstan, but be careful - the long rear circuit board will no longer be attached without that black screw. It will try to fall off.
According to the service manual, and my own personal experience, Huntsville sourced the tape decks for these from two sources: Alpine and Shinwa. This sticker indicates that we're looking at one of the Shinwa mechanisms.
Replacing the belt is very easy on this unit. All you need to do is remove the four screws holding the mechanism to the tray, and the belt is right there. Nothing is obstructing it at all. String it back in there as pictured above.
A look inside the slot shows us some very dirty pinch rollers. Clean them, the capstans, and the head with some isopropyl alcohol on a cotton swab or three.
A look at the unit with the shroud removed. The rear pinch roller and capstan can be accessed through the hole indicated in red. And yes, that is a Hershey Kiss flag you see in there. We know what this Caravan's owner liked snacking on, don't we?
Time to put it all back together. On this deck, that won't be hard.
One last little tip before I wrap up this article. You can switch the tuner between US and European modes. I've gone to Europe mode in this shot.
Now, this may get a bit confusing. The service manual says that you should hit set, sel, and then preset button one three times. This does not work for this particular deck, which bears a part number not covered by the manual. To do it on this deck, turn it on and set it to FM. Hit set, sel, and then button one five times. The deck will switch off. When powered back on, the tuner will do what you see above: tune AM in weird steps, and FM in more precise steps in usual.
This concludes my look at the venerable Infinity I. Next time, I'll get into the first deck to bear the Infinity logo (it came before the Infinity I), and one of the others based on the Ultimate Sound deck of the mid-1980s.
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