Bose System Question
Thread Starter
Max G’s
Joined: Nov 2008
Posts: 2,751
Likes: 79
From: Monroe OH
NCM Sinkhole Donor
Bose System Question
Have a 91 Coupe with Bose system. Front two speakers stopped working first and would just squeal a little. The rear speakers would still work and could turn up volume enough to override the static and squeal from the front. Then one day the rears stopped working as well. I disconnected the front speakers and pulled the rears out to see if could see anything visual and plug in some other amps from another 91. Still nothing, but can barely hear sound from radio coming out of the rears now. Question is; do the front and rear speakers have to be plugged in for any of the speakers to work?
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 207
From: Orlando FL
The speakers which have a built in amplifier in the box are all independent. You can have a problem with one and would not affect the others. The squealing are bad electrolytic capacitors and I will leave the thread with links with info on repairing them.
http://forums.corvetteforum.com/c4-t...-and-more.html
The one common element is a item called the Bose relay. It supplies 12 volts to the amplifier boards in the speaker boxes. If there is no power, then there will be no sound from any of the speakers. I believe in your car the relay is in front under the dash.
http://forums.corvetteforum.com/c4-t...-and-more.html
The one common element is a item called the Bose relay. It supplies 12 volts to the amplifier boards in the speaker boxes. If there is no power, then there will be no sound from any of the speakers. I believe in your car the relay is in front under the dash.
Thread Starter
Max G’s
Joined: Nov 2008
Posts: 2,751
Likes: 79
From: Monroe OH
NCM Sinkhole Donor
The speakers which have a built in amplifier in the box are all independent. You can have a problem with one and would not affect the others. The squealing are bad electrolytic capacitors and I will leave the thread with links with info on repairing them.
http://forums.corvetteforum.com/c4-t...-and-more.html
The one common element is a item called the Bose relay. It supplies 12 volts to the amplifier boards in the speaker boxes. If there is no power, then there will be no sound from any of the speakers. I believe in your car the relay is in front under the dash.
http://forums.corvetteforum.com/c4-t...-and-more.html
The one common element is a item called the Bose relay. It supplies 12 volts to the amplifier boards in the speaker boxes. If there is no power, then there will be no sound from any of the speakers. I believe in your car the relay is in front under the dash.
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 207
From: Orlando FL
There is a unit called the tuner which performs the actual radio tuner functions but also has a pre amp for each speaker enclosure. The speaker enclosures (or box) has an amplifier board and speakers in it. Four speaker boxes, four amplifier boards.
Most of the problems with the squealing and fuzzy sound are on the amplifier (speaker) boards.
The tuner (not sure where it is located in the 91, (dash?)) rarely causes any problems but of course can go bad.
Repairing the amps are not terribly hard. Usually a few dollars for capacitors verses a car audio business that charges a whole lot more ($50+?). If you read my link you can get a lot of information. If electronics is not your thing and do not want to solder, then send it out.
But the most important item is to correctly diagnose the problem correctly so you work on or send out only the defective units.
Thread Starter
Max G’s
Joined: Nov 2008
Posts: 2,751
Likes: 79
From: Monroe OH
NCM Sinkhole Donor
I think there may be some confusion here but just want to lay it out simply.
There is a unit called the tuner which performs the actual radio tuner functions but also has a pre amp for each speaker enclosure. The speaker enclosures (or box) has an amplifier board and speakers in it. Four speaker boxes, four amplifier boards.
Most of the problems with the squealing and fuzzy sound are on the amplifier (speaker) boards.
The tuner (not sure where it is located in the 91, (dash?)) rarely causes any problems but of course can go bad.
Repairing the amps are not terribly hard. Usually a few dollars for capacitors verses a car audio business that charges a whole lot more ($50+?). If you read my link you can get a lot of information. If electronics is not your thing and do not want to solder, then send it out.
But the most important item is to correctly diagnose the problem correctly so you work on or send out only the defective units.
There is a unit called the tuner which performs the actual radio tuner functions but also has a pre amp for each speaker enclosure. The speaker enclosures (or box) has an amplifier board and speakers in it. Four speaker boxes, four amplifier boards.
Most of the problems with the squealing and fuzzy sound are on the amplifier (speaker) boards.
The tuner (not sure where it is located in the 91, (dash?)) rarely causes any problems but of course can go bad.
Repairing the amps are not terribly hard. Usually a few dollars for capacitors verses a car audio business that charges a whole lot more ($50+?). If you read my link you can get a lot of information. If electronics is not your thing and do not want to solder, then send it out.
But the most important item is to correctly diagnose the problem correctly so you work on or send out only the defective units.
Thread Starter
Max G’s
Joined: Nov 2008
Posts: 2,751
Likes: 79
From: Monroe OH
NCM Sinkhole Donor
Update, accessed the relay under dash. Not too difficult to access. Just remove knee bolster, the piece that is directly under the dash and your center air duct comes out of. Once knee bolster is removed could see the relay. The Bose relay was the one on the right side of the steering wheel, there are only two relays on that side and it is the once toward the left. Speakers still didn't make sound loud enough to hear. Came back in and looked at the Service Manual and it says that the relay energizes the amps through the courtesy "CTSY" fuse and that fuse is good. Didn't see in the service manual about a pre amp on the tuner itself. Is the pre amp inside the tuner? I'm 95% positive that the amps on the speakers are good.
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 207
From: Orlando FL
On the speakers boxes is a connector with 4 wires. Black is ground and orange is 12 volts. Measure it make sure it's there.
You will not see any real documentation on the pre amp in the tuner. It's just a given that it is there because you need some kind of driver the feed to the speaker (box) amplifies. I was just trying to make a point for clarity and differentiation.
Suggestions
Check and clean the connector that feeds the tuner. You might have to do the same with the connectors on the radio control head. Does your antenna go up and down? The Bose relay does (I know in the 94 it does) feed power to the motor.
It is unlikely that all 4 speaker boxes are so defective that they would not produce any audio. I would look in the tuner and radio head area for a common problem. You may have to pull out the tuner and head and give them a good visual, might be a clue.
You will not see any real documentation on the pre amp in the tuner. It's just a given that it is there because you need some kind of driver the feed to the speaker (box) amplifies. I was just trying to make a point for clarity and differentiation.
Suggestions
Check and clean the connector that feeds the tuner. You might have to do the same with the connectors on the radio control head. Does your antenna go up and down? The Bose relay does (I know in the 94 it does) feed power to the motor.
It is unlikely that all 4 speaker boxes are so defective that they would not produce any audio. I would look in the tuner and radio head area for a common problem. You may have to pull out the tuner and head and give them a good visual, might be a clue.
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