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by Jeremy Schrag
It seems hard to believe now, but when the 21st century began, many car makers were still putting cassette decks into their vehicles. A good many customers balked at the idea of swapping their tapes for a medium that was relatively expensive. Yet, many of these customers also had more than a few compact discs they wanted to play in their cars.
As the new millennium neared, most vehicles could still get CD/cassette combo units, but for the second generation LH body cars (Concorde, Intrepid, LHS, 300M) they decided a new option was in order: a cassette deck with a separate in-dash CD changer. No longer would the customer be forced to enjoy just one CD at a time, as was the case with the mechanically cramped combo decks. Now, the buyer of a top-of-the-line Chrysler or Dodge could still enjoy the odd cassette, but with the convenience of a separate CD changer placed right there below the deck to hold several compact discs as well. (At the time, some competitors were still using trunk-based CD changers.)
It was a popular option, when it worked. Unfortunately, many of these early in-dash changers developed issues; problems with these early changers were so widespread that Chrysler issued a technical service bulletin to address them.
Today, I'll be looking at the head unit side. The unit I have in hand comes from a 2000 Concorde and goes by the sales code “RBB,” as you can see above in the inset. I do have the CD changer that goes with this unit - we'll be looking at that in a future article, due to its complexity.
In the meantime, I'll take this unit apart and show you what it's made of.
This particular deck, as we can tell from the supplier code on the label, comes from Chrysler's Huntsville Electronics division, now owned by Siemens. Four screws secure the top cover to this unit, and are arrowed in red. We'll get to those later.
The bottom cover of this unit holds no screws for us to worry about. As is usually the case with these Huntsville decks, this unit is rather easy to get apart.
The back panel: blue arrows indicate two of the three bottom tray screws, red indicates the top cover screws. There are three other screws in this picture, but we don't need to worry about them yet. All screws used in this deck are Torx style, in sizes T-8, T-10, and T-15.
Five electrical connectors also grace the back panel. From left to right, they are the Motorola antenna connector, CD changer connector, CCD bus connector, and the two usual black and gray harness connectors that all Chrysler decks up used, until 2001, to interface the deck with the main vehicle harness.
The two spade terminals you see on the case are for grounding: this is where you plug in your Infinity amp relay ground, if present. If you cannot find such a wire in your dash, don’t worry. Most cars new enough to accept one of these round faced decks do not have the old amp relay ground wire anymore. Those wires were mainly found in the older “amp on speaker” Infinity systems that were used in the late eighties and early nineties. The LH body cars have always used a single central amplifier to power all speakers, which do not have or need that extra relay ground wire. Even so, Chrysler has provided these two locations to attach them if need be.
On the left side panel, we find the heatsink for the amplifiers. Aside from the two faceplate screws arrowed in red, there is only one yellow arrowed screw to worry about here. This is the screw that holds the amplifier chip bracket in place.
The right side panel is even simpler. The only screws present, arrowed in red, are for the faceplate.
Let's get that off now, shall we? Turn the deck over, so the bottom is facing up.
After removing all four screws, and then releasing the clips on the top and bottom, we can easily pull the faceplate forward and swing it down like so.
There are two connectors to release. The one indicated in yellow is merely friction fit - you can just pull it right out. The ribbon cable by the red arrow, however, will require a look at the inset. There is catch on this one, as you can see. Press it in, then pull the ribbon cable out. This ribbon cable connects the mainboard with the rotary encoder (volume control).
Now, we can remove the faceplate.
Should you require access to the membrane switches on this deck, you must remove the circuit board and rotary encoder. It's very easy - merely remove all red arrowed screws, pull the equalizer, fader, balance, and volume knobs off, and the board and rotary encoder come right out.
The four main components of the faceplate assembly are seen here. We have the membrane switches in one big gray strip on the top left, the housing on the right, the circuit board on the bottom left, and the rotary encoder in the middle.
The board used incandescent 12 volt micro-lamps, as was the case for most eighties and nineties Chrysler decks, however they are no longer mounted in twist off removable bases. Instead, these are permanently married to their bases and soldered in. I do not yet know where to find exact replacements for these, but with some careful work you could replace these with standard 3mm grain of wheat bulbs.
Don't forget to order new blue filter socks as well, as the ones used here will not fully fit over standard grain of wheat bulbs. They will cover only the ends, leaving the rest of the bulb bare.
At this time, only eBay seems to provide easy sources for grain of wheat bulbs and filter socks, though you may also get lucky at a model train supply store.
Our next step in the process of taking this deck apart is to remove the bottom tray and cassette assembly. There are three screws to do so: one is indicated in red here, and the other two are on the back panel.
Remove those now, make sure the unit is resting on its top cover, then flip the bottom tray up towards the rear.
A single ribbon cable joins the cassette module to the mainboard. I've added an inset to this picture to show you how to release it. Just push the two clips out to the side, and the connector pops right out and off.
We'll take a look at the cassette module next. This particular mechanism is open to servicing — we can already clean the pinch rollers, magnetic head, and capstans.
To remove the mechanism for belt access, we must disconnect two connectors... see the insets. The connector on the left (purple), is press-fit. Using a small flat bladed screwdriver, gently pry it off the board. Pull the wires out of the big black bracket so that you can remove the cassette mechanism. On the right (blue), we have a ribbon cable in a locking connector. Slide the locking collar forward, as shown in the inset, then pull the cable out.
When replacing these connectors, take care to be sure the right side ribbon cable is fully inserted in the connector. On these particular connectors, it's easy for the cable to catch inside the connector and make you think it's fully inserted when in fact it isn't.
Now that these connectors are out of the way, remove the four T-8 screws whose positions are indicated by the red arrows, and remove the cassette mechanism.
The cassette belt is easily accessed once the mechanism is out, as you can see here. But how does one measure the belt for replacement? Let me show you now.
There are two critical measurements we want to get when it comes to cassette belts. First, you need to measure the width of the belt. That's the easy part. Second, you need to find the internal circumference, and then subtract 5-10% to compensate for belt stretch. Over time, these belts always stretch out and you want to make sure your new belt is a little tighter than the one that just came off.
In the above picture, you see my method for measuring internal circumference. In front of a ruler or tape measure, lay the belt out as shown using two small screwdrivers, toothpicks, or other similar implement to take out the slack. Do not stretch the belt, just pull it out straight. Measure the length of one side, then multiply by two. Next, take the result and deduct that 5-10% allowance for belt stretch. Presto, you have your internal circumference. Convert your measurement to inches, if necessary, and then order yourself a new belt.
In this example, I would go looking for a belt with a 15.4" or 15.5" internal circumference with a belt thickness of 0.39."
Sometimes, as was the case with an old RCA cassette deck I recently worked on, these belts can actually rot themselves into a strip of goo and wrap themselves around moving parts. These present an extra challenge. First, you have to clean the remains of the belt off of any surfaces they've become married to. I use isopropyl alcohol to do this. Make sure you measure the width of any belt sections that may be left, so you have a width measurement for the new belt.
Then, you need to work out how the belt was originally installed in the mechanism. This can often be quite difficult in a home stereo cassette deck, in which there may be many belts, but usually is not so hard for Chrysler car stereos. Once you know how the mechanism works, take a piece of string and wind it around the tape path. Pull it tight, snip the string, then measure the resulting length of string. That's your internal circumference. Don't forget to deduct 5-10% from the resulting number.
Now that we've seen the cassette section, let's look at the mainboard. Take off the top cover, and you should have this view. From here, you can already address any bad solder joints the deck may have. I've spotted several in this one.
Removal of the mainboard is also possible, should you be looking to get access to the amplifier chips and voltage regulator chip. Take out the three blue arrowed screws. Remove the screw on the side panel for the amplifier chip clamp I showed you earlier.
De-solder all twist tabs, then bend them away from the mainboard. Turn the whole deck over.
Our next step is to remove the outer portion of the black and gray connectors. They are clipped in... yellow arrows indicate the clips. Push those clips in, then pull the plastic housings of these connectors out the back.
Now, we can finally get the mainboard out. Turn the unit back over, so the board's solder side is facing up again. Gently work the board up and out of the chassis.
The voltage regulator is the lone chip up on top, next to the metal bracket. The amplifier chips are on the right side... normally there is a metal clip installed behind these to hold the chips to the side panel heatsink, but I have removed it to get a look at the part numbers. All three of these Philips sourced parts use proprietary Chrysler part numbers, so replacement will be difficult. The voltage regulator bears the part number 4813621AA, while the two amplifier chips go by the number 4813699AA.
This concludes my look at the RBB cassette deck. Next time, we'll take a good long look at the four disc in-dash changer that goes with this deck.
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