Bose speaker 'drumming'
Thread Starter
Burning Brakes
Joined: Sep 2011
Posts: 764
Likes: 19
From: odessa FL
Bose speaker 'drumming'
Have a 95 with a speaker/ amp issue. It seems to be only the pass rear unit and is intermittant. Produces a rapid "drumming" sound that remains constant, ie just as loud at barely on to full volume. Does not change with speed or if engine on or off. When not making this sound it still thumps like new. If it does not start at start up it has not as yet started while driving. Happens about 50% of the time. Connections seem ok. Ground issue? Amp?
Thoughts?
Thoughts?
Racer
Joined: Oct 2012
Posts: 350
Likes: 2
From: Huntsville AL
Have a 95 with a speaker/ amp issue. It seems to be only the pass rear unit and is intermittant. Produces a rapid "drumming" sound that remains constant, ie just as loud at barely on to full volume. Does not change with speed or if engine on or off. When not making this sound it still thumps like new. If it does not start at start up it has not as yet started while driving. Happens about 50% of the time. Connections seem ok. Ground issue? Amp?
Thoughts?
Thoughts?
I guess tonight after work would be a good time for me to pull mine out and fix it. That way I can come back and tell you the correct location and value.
Racer
Joined: May 2013
Posts: 405
Likes: 15
From: Panama City Beach Florida
94 Conv LT1
Have a 95 with a speaker/ amp issue. It seems to be only the pass rear unit and is intermittant. Produces a rapid "drumming" sound that remains constant, ie just as loud at barely on to full volume. Does not change with speed or if engine on or off. When not making this sound it still thumps like new. If it does not start at start up it has not as yet started while driving. Happens about 50% of the time. Connections seem ok. Ground issue? Amp?
Thoughts?
Thoughts?
Factory Car Stereo Repair, Inc
Longwood FL 32750
800 428 1909
www.carstereohelp.com
Cost me $80 each amp plus shipping. Hope this helps!
Racer
Joined: Oct 2012
Posts: 350
Likes: 2
From: Huntsville AL
The bad caps are C7 & C8 (the designations are silk screened on the circuit board, along with the polarity of the caps).
NTE NEV47M16BA - CAP-47uF 16V RADIAL
Model:
NTE NEV47M16BA
| Catalog #: 55047280
Price:$0.40
They are 40¢ each at Radio Shack. A $5 roll of solder wick and a $4 soldering iron from WalMart and your amps will be as good as new. The first time I did this repair, I replaced every electrolytic cap on the board, one at a time. Replace one and test, replace one and test. There was no improvement until I went to remove C7 and the leads pulled right out of the can because the cap was dried out. C8 was the same. It is a quick job - quicker than a trip to the post office for sure.
NTE NEV47M16BA - CAP-47uF 16V RADIAL
Model:
NTE NEV47M16BA
| Catalog #: 55047280
Price:$0.40
They are 40¢ each at Radio Shack. A $5 roll of solder wick and a $4 soldering iron from WalMart and your amps will be as good as new. The first time I did this repair, I replaced every electrolytic cap on the board, one at a time. Replace one and test, replace one and test. There was no improvement until I went to remove C7 and the leads pulled right out of the can because the cap was dried out. C8 was the same. It is a quick job - quicker than a trip to the post office for sure.
Racer
Joined: May 2013
Posts: 405
Likes: 15
From: Panama City Beach Florida
Amp boards
The bad caps are C7 & C8 (the designations are silk screened on the circuit board, along with the polarity of the caps).
NTE NEV47M16BA - CAP-47uF 16V RADIAL
Model:
NTE NEV47M16BA
| Catalog #: 55047280
Price:$0.40
They are 40¢ each at Radio Shack. A $5 roll of solder wick and a $4 soldering iron from WalMart and your amps will be as good as new. The first time I did this repair, I replaced every electrolytic cap on the board, one at a time. Replace one and test, replace one and test. There was no improvement until I went to remove C7 and the leads pulled right out of the can because the cap was dried out. C8 was the same. It is a quick job - quicker than a trip to the post office for sure.
NTE NEV47M16BA - CAP-47uF 16V RADIAL
Model:
NTE NEV47M16BA
| Catalog #: 55047280
Price:$0.40
They are 40¢ each at Radio Shack. A $5 roll of solder wick and a $4 soldering iron from WalMart and your amps will be as good as new. The first time I did this repair, I replaced every electrolytic cap on the board, one at a time. Replace one and test, replace one and test. There was no improvement until I went to remove C7 and the leads pulled right out of the can because the cap was dried out. C8 was the same. It is a quick job - quicker than a trip to the post office for sure.
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 206
From: Orlando FL
All of this is good information. I am going to throw in my 2 cents on a thread I wrote on 06 on the repair of the speaker amps. A lot of detail and some of the best links you can find.
Too much to rewrite and more good information in the thread.
http://forums.corvetteforum.com/c4-t...-and-more.html
Too much to rewrite and more good information in the thread.
http://forums.corvetteforum.com/c4-t...-and-more.html
Thread Starter
Burning Brakes
Joined: Sep 2011
Posts: 764
Likes: 19
From: odessa FL
Its been a LONG time since I took electronics in HS [73-74] but I can prob manage the soldering if I know which ones are bad. I dont have any way to check the microfarad rating. But refresh my memory...will a bad cap have no continueity? How do you tell its bad?
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 206
From: Orlando FL
2 - 47, 1 - 4.7, 3 - 10, 2- 1 mfd for a start.
Try to get voltage ratings that are the same or slightly higher. If they are to high it won't hurt, but you will not be able to physically install them.
Get yourself a solder puller (sucker) from radio shack and you will do a better job and not mess up the board. Practice on using it before you take to the real board (got to be fast). Don’t do any solder bridges…careful. You will have to take some goop off the top of board carefully, you'll se.
Check page 11 from the first link, you can see the basic layout and values of the capacitors.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Racer
Joined: Oct 2012
Posts: 350
Likes: 2
From: Huntsville AL
As someone else mentioned, the caps and large inductors are stabilized with a liberal gob of hot melt glue or similar material. Use a knife or exacto and slice down through the goog between the caps and inductor coils but stop shy of the PWB - you don't want to risk cutting any traces, and don't knick the coating on the inductors. Use some needle nosed pliers to pull the potting out. In all likelihood the bad caps will pull off of their leads and come out with the potting because they are dried out. That is fine, it makes the desoldering job easier.
At any rate, BOTH back channels in my car now sound great, so again, thanks for getting me off the dime.
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 206
From: Orlando FL
One of the major weak links of components is coupling capacitor 172, 10mdf. When this cap is weak, it really muddies the frequency response and lowers the volume (power) of the output of the amp.
But my sound is clean and plenty loud enough for you are only couple feet from the speakers. The highs are crisp and the base is that nice thumpy sound.
My friend in my corvette club in his C5 has been trying to get his radio fixed by the dealer. But there is nothing wrong, it's just a different animal and different vintage radio. Mine sounds better, he likes his car but my radio better.