Removal, Repair and Replacement of OEM Bose Speaker/Amp Units

This page goes over the basics of the Bose stereo system, causes for failure and amplifier replacement procedure.

Authored by Drew on 2000.07.22, Last Updated: 2000.09.21

Disclaimer: Any and all content is solely my opinion and is not the responsibility of anybody else.
Copyright: may be copied as long as credit is given and MUST BE distributed without charge.

Tools Required:

Phillips #2 screwdriver
Ratchet, ¼" deep socket, 10 mm [deep] socket
10 mm combination-wrench
Putty knife and soft cloth

Parts Required:

Repaired or replacement amplifiers (See background for options and sources)
Thermal Grease – (NTE 303)
Plastic/Vinyl dressing – (Armor All)
Leather Dye and Leather Polish – (Kiwi)

Background:

Tuning
Each amp is tuned for the car AND the placement within the car. Amps from other cars cannot be interchanged and have them expect to sound anywhere as good. In my opinion, even close sounding, would be very lucky.

The NSX has an extremely small interior and therefore the bass must be driven to extremes to sound correct. The mids and highs would carry very well and therefore only the bass would have to be boosted high above what would be necessary for a normal car.

This extreme bass boost would cause major heat problems, which leads us to the next point...

Heat Dissipation
While the components of the board are of *quite* high quality, the heat dissipation abilities are below average, if not downright poor.

The RF shield takes some of the heat, but it is not efficient. If you look closely, there are copper pads below each transistor (you may have to hold the board up to a strong light to see them). These pads actually dissipate most of the heat and are a very poor compromise. The transistors are plastic packed and not suited to good heat dissipation and there is no factory applied thermal grease either.

The small caps also "wear out" because they dry out. Components are usually rated in thousands of hours of use. Those caps should function a couple of thousand hours at "normal" temperature. For every increase of 10 C the useful life of the cap is decrease by 1/2, conversely for every decrease of 10 C the useful life is 2x (+20 degrees would be 4x, +30 degrees less would be 8x, etc...). So the smaller caps going bad should be no surprise to anyone.

Factoids
The round caps are electrolytic, the yellow caps are film, the round bulbous orange one is tantalum.

Amplifier Markings
RF Shield: Front 137637- 2205, PCB sticker - 112 2205, P/N Date on back 136898 1091
RF Shield: Rear 137637-2206, PCB sticker - 111 2206, P/N Date on back 136898 0491

Design
Each amp made differently and will put out different signals based on several things: placement, speaker size, enclosure size and power.

You CANNOT mix'n match Bose amps on a gross scale. There is something called On-Board Equalization, which means the soldered components on the board create the desired tuning. To make matters worse the door amps have six [6] pins, while the foot well speaker amp has seven [7] pins.

bose_ampback.jpg (57502 bytes)While the basic design is the same in almost all cars, the tuning is quite different. To make the sound accurate again, you must compare the boards and swap out the component differences....this includes the underside surface mount components. A very difficult task indeed.

Most cars have much more interior space and therefore the mids and highs are emphasized and bass is not. This will not work with the NSX...it will sound either dry or quite irritating (like all the treble is turned up on your home stereo).

Failure
All Bose amps will eventually fail due to inability to dissipate heat. The louder you listen to the stereo the faster they will fail, it is a function of a square (twice as loud = 4x rate of failure).

Allegedly the problem with the NSX amps were solved in the1996 model year (but I really doubt it). Bose changed capacitor makers in `93 and have not had as many problems since.

Infiniti has a long standing replacement policy on their Bose amps, because they are mounted on top of the gasoline tank. They fry or get too hot and they will replace them for you. No other car maker will do this outside of the warranty.

On 2000.09.19 Honda of Japan has recalled 556,924 passenger cars in Japan covering the model years from 1991 to 1997 as they "may heat up excessively and cause speakers to catch fire." There are no plans for Honda of America, per an internal notice dated 2000.09.20, that "American Honda has no complaints of this type in the US market; therefore, the US is not affected by this recall."

 

Repair:

Option I – Third Party Replacement
For about $250 you can get replacement amps (not made by Bose) from Amp Options (e-mail at: [email protected] or call between 8:00 AM to 9:00 PM EST at 770.638.0359) Has better warranty than Bose, might be better made; apparently not NSX specific at this time.

One site that sells these particular amps for $70 apiece. They say they have been selling them for 4 years and have not had a failure. If you have any more questions please feel free to e-mail or phone me 517.790.2949. ask for Michael. mnrelectronics.com/ampoprepbost.html 

Option II – Have Bose Fix them for you!
Pay Bose. They have tuned each amp to fit the car and its enclosure. For the original stock sound it is better to have the amps rebuilt than to replace them with different part numbers, but the fix may not last very long. Send the entire enclosure (along with a $75 money order) back to them to get them rebuilt. BOSE 800.231.2673.

Bose Corporation
125 Fisher Street
Attn: John Villa - OEM QA
Westboro, MA 01581

Success is mixed from the people who use the repair option. Many have had the amp fail within months of the repair operation. The only components replaced are those that have currently failed. Components that have not yet failed (or about to fail) are not replaced, possibly sending you back a tired amp.

Option III – Repair them yourself
Those style of amps are used in just about every type of Bose install for the past 15 or years. So any car new car can be robbed of parts to fix the NSX amps. Looking at the transistors, two of them are made by IR and have Bose's generic part number: 137110. This part number does not exist and appears (high confidence) to be a relabeled IR's FIZ24 transistor.

Here is a link to the FIZ24 matches on IR 

Here is the particular part number they recommend (requires free Adobe Acrobat Reader)

Digikey sells these for $1 each. 

The transistor IC replaced was Q1.

The caps replaced in a sample Bose repaired amp were: C110*, C130*, C16*, C183, C172, C203*, C31, C7, C8, C25, and C19.

Note that the ones with a * were replaced with what appear to be tantalum capacitors instead of the usual electrolytic caps. I recommend all caps be replaced with tantalums, if at all possible.

Option of Last Resort – Honda Dealership
Purchase replacement speaker enclosures from the Dealer. They apparently run about $950 per enclosure.

 

Method:

Door Speaker – Passenger or Driver side

bose_trimplate_large.jpg (61567 bytes)

 

bose_doorlockcable_large.jpg (57500 bytes)
Figure C

 

bose_puttyknife_large.jpg (54789 bytes)
Figure E

 

bose_doorpaneltop_large.jpg (59516 bytes)
Figure G

 

  1. Lower window fully.
  2. Remove leather wrapped triangle shaped trim piece that covers the interior handle area. [Figure A]. Hint: Use either deft fingers or a cloth covered putty knife to pry up between the leather ‘scales.’
  3. Remove the Phillips screws [eight total: 4 black, 4 gold] from the inner handle area. [Figure B] You will need to make use of both hands to remove the gold screws, one to lift the handle and the other to operate the screwdriver. Note: The black screws fasten the metal parts of the handle and the gold screws fasten the plastic parts of the handle. Do not mix these up upon reinstallation or you will surely ruin the inner door handle.
  4. Pull the inner handle forward and unclip the blue sheathed part of the cable. [Figure C] There are three positions on the blue clip, default is the middle position, but make note of which position your cable is positioned for reinstallation.
  5. Undo the cable head from the inner door handle.
  6. Disconnect the door lock connector.
  7. Remove the front and rear sash covers [Figure D]. Use a cloth covered putty knife to pry them off the door [Figure E]. Each sash is secured by gold colored metal clips [2-rear, 3-front] and chances are good that you will render one or all of them useless [p/n: 90615-SK7-003, $1.22 each]. Be sure to place all the metal clips back into the door, if they are inadvertently remain on sash cover as in photo (if this occurs, remove the clips and replace back in the door).
  8. Remove the Phillips screws [7 total] that attach the perimeter of the door panel. They are cleverly hidden behind the door weather-stripping [Figure F]. This is another two-handed procedure: Use one hand to push back the stripping and the other to use the screwdriver to remove the screw. Once all the screws are removed, be sure to place all the door panel plastic tabs on top of the weather-stripping.
  9. To remove the door panel you first must make sure ALL of the door panel tabs are visible on top of the weather-stripping. Then grab the bottom of the door panel and pull it toward you about 20cm (10 inches). Now the tricky part: slowly pull the rear portion of the door panel toward you while pushing up. [Figure G] The door panel should slide out of the stainless steel retaining strip along the top of the door.
  10. Do not let go of the panel or pull too far back away from the door or you will stretch the wires and connectors. [Figure H] Rather, brace the door panel against your legs and disconnect the wire harness connectors. Driver’s-side disconnect order: Security LED (green/black), Mirror (green), Window (gray), Trunk (brown/clear), Courtesy light (clear). The passenger side only has mirror and courtesy connectors. Note: Do NOT close door with the connectors hanging down, you will need to secure them before you close the door or you will cause unnecessary damage.

 

bose_innerhandle_large.jpg (60881 bytes)
Figure B

 

bose_sashcover_large.jpg (59848 bytes)
Figure D

 

bose_paneltab_large.jpg (64702 bytes)
Figure F

 

bose_doorconnectors_large.jpg (59859 bytes)
Figure H

 

Speaker Removal and Repair

You have now exposed the black plastic speaker enclosure assembly. The actual speakers are 6-inch diameter, 1-ohm impedance and fastened at only three points. You should not have to remove the speaker at anytime during this procedure.

  1. Take out the enclosure by removing the five [5] Phillips screws and unclip the speaker connector.
  2. For those opting to have your amplifiers repaired by Bose, stop disassembly and send the entire enclosure to vender of your choice. Some independent repair services only require the amplifier itself. (See Background, above). When you have received the repaired items, skip to Step 13 to complete the procedure.
  3. Move to a clear and clean workbench or desk.
  4. Use the SAE ¼" deep socket to remove the seventeen [17] hex screws that fasten the enclosure together.
  5. Make note of the position of the wiring harness, insulation and foam gasket. [Figure I]
  6. Peel back the foam gasket and insulation.
  7. Unclip white connector from the internal Bose amplifier and push the wiring harness off to the side.
  8. Remove the four [4] Phillips screws that secure the amp to the enclosure. For those opting to have their amps repaired by a non-Bose Factory service, stop now and send the amp/enclosure for repair.
  9. For those who have replacement amps in hand or have received their repaired amps, I recommend that you write some important information on the exterior of the amplifier. [Figure J] For example: date of install, odometer reading, place of amp purchase/repair, your name and how to contact yourself (if you ever sell the car).
  10. Pull/pry off the RF metal shielding.
  11. Pry up each of the four [4] transistors and spread thermal grease on both sides of the transistor black plastic package. This is in effort to dissipate the destructive heat build up that destroyed the amp in the first place. [Figure K]
  12. Replace metal shielding.
  13. Replace the amp back into the enclosure and securely tighten the four [4] Phillips screws. Tighter is better for heat dissipation purposes, but do not over-tighten to the point of stripping the plastic threads.
  14. Connect the white speaker connector back onto the amp.
  15. Replace the insulation and foam gasket. Insure the wire harness is under the gasket.
  16. Place the other half of the speaker enclosure over the gasket and replace the seventeen [17] screws.
  17. Install the speaker enclosure back into the door with the five [5] screws and reconnect the speaker connector. Just tighten the screws just enough to feel the resistance of the plastic fastening tabs, any more than that will break the tabs off. Do not confuse the speaker enclosure screws with the door panel tab screws, as the enclosure screws are shorter.
  18. Test the stereo at this time [NOW!] to make sure this speaker is working properly. Also, take the time to spray vinyl protectant and silicone spray everything on the door that you think can use it. Make sure you coat the exterior door panel with protectant, as it will act as a lubricant when you are reinstalling it.
  19. Reinstallation of the door panel: connect the connectors [driver –5, passenger –2] and "hang" door panel on top stainless steel retaining strip. Push the top-front of the door panel into the strip and gently force the rest of the panel into the strip.
  20. Place all of the door panel retaining tabs under the weather-stripping and install a screw into each tab. DO NOT OVERTIGHTEN. The tabs are easily broken. Just tighten the screws down to the point of feeling resistance of the tab against the door metal and STOP!
  21. If the leather is at all scuffed, faded or worn, you can dye and later apply polish. [Figure L]

 

bose_doorenclosure_large.jpg (60804 bytes)
Figure I

 

bose_ampoldnew_large.jpg (63249 bytes)
Figure J

 

bose_ampkit_large.jpg (63084 bytes)
Figure K

 

bose_kiwi_large.jpg (198836 bytes)
Figure L

Passenger foot well bass speaker, passenger floor pan

  1. Remove the dashboard lower cover that is secured by two [2] 10 mm bolts. If your car is equipped with keyless entry, then two connectors will have to be detached.
  2. Disconnect the gray and brown connectors on enclosure. These are the amplifier power/signal and center speaker output.
  3. Peel back console and floor pan carpet. Exposing a silver colored metal cover. [Figure M]
  4. Loosen upper bolt and remove the lower two [2] 10 mm bolts.
  5. Slide out and remove the cover, exposing the black foot well connector.
  6. Remove the four [4] 10 mm bolts and remove the foot well speaker. [Figure N].
  7. Move to work bench area and remove the fifteen [15] ¼" SAE screws to open the enclosure.
  8. Replace amplifier and gently reassemble. (See above "Door Speaker" for details.)
  9. It is a bit difficult to align the enclosure on its bracket, but take care not to strip any fasteners OR damage any wires.
  10. Replace cover and tighten bolts.
  11. Reconnect the harness connectors.
  12. Test system. If satisfied: replace carpet.
  13. CONGRATULATIONS!
bose_footguard_large.jpg (183988 bytes)
Figure M

 

bose_floorpan_large.jpg (177049 bytes)
Figure N

Enjoy your NSX and take a drive.

 

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