This is the hardest step. As mentioned, each meager-size speaker and amplifier is contained in a box to give the appropriate sound. To properly work on the system, remove the interior doorskin and metal plate thats bolted to the inside of the door. This is the only way to remove the entire speaker-box assembly.
Once the box is removed, separate the two halves of the box to reveal the amplifier. Note that there is some filler material inside the box; this is an important part of the system. Because of the space requirements, GM could not install a larger box and speaker. This filler material makes it sound like its bigger.
Each speaker has an amplifierthis is typically the problem with the system. Some symptoms that may indicate the amplifier is bad include a hissing noise or a sound out of the speaker thats barely discernable. These amplifiers can be rebuilt, but Corvette Specialist provides all-new amplifiers to its customers.
One of the situations that shortens the life of the amplifiers is a capacitor that starts to leak. The fluid eats away at the other surrounding components.
You can test each speaker by removing it from the speaker box .
Use a short jumper wire to power the speaker with a double-A battery. If you see the speaker move when you put power to it, the speaker is working properly. If there is no movement, the speaker should be replaced. It is recommended that you replace speakers and amplifiers in sets. All of the speakers are the same age as the one that quit, so its just a matter of time before the others quit, too.
There are differences between the boxes used for the rear speakers. The coupes had boxes that slid into the side of the rear hatch area.
The convertibles used boxes along with a flat panel that became part of the floor area immediately behind the seats.
Once you remove the flat plate from the convertible style of rear speakers, you can access the amplifiers just like the other boxes.
Corvette Specialist can also repair other components of the Delco-Bose system. We had a head unit from a 95 Corvette that has white lettering, and we wanted to match the orange lettering of the rest of the dash in our 90 Corvette. Corvette Specialist rebuilt our unit and installed the older-style faceplate. The newer head units were slightly better, so Corvette Specialist provided us with a matching faceplate and an upgraded radio.
There were changes made to the receivers during the time they were used in C4 Corvettes. One of the more obvious is that, while the 84-89 units were contained in one unit in the dash, the 90-96 systems consisted of a head unit in the dash and a receiver unit under the dash on the passenger side of the car. For obvious reasons, they will not interchange.
The receiver units from the 90-96 systems differed between the Bose and the non-Bose models. The Bose model has no fins on the heat sink located on the back of the unit, while the non-Bose receiver has fins on the heat sink. They cannot be interchanged.
A problem with the head units we hear about quite often is that a CD installed in the unit will not eject. There is a small rubber bumper inside the unit that rests on the CD when its not in use. If the CD is left in the unit for more than a day and not played, the rubber bumper can become fused with the CD due to heat in warmer climates. Sometimes the CD can be ejected once the system cools down, but many times youll have to disassemble the unit to break the rubber bumper loose from the CD. Chris at Corvette Clinic says its best to simply remove the CD when you wont be listening to it for a while.