Troubleshooting OEM sound system

Hi all,

Recently picked up the car a few weeks ago knowing it had a problem with no sound from the speakers. I have searched, and found this could be due to the speaker amps failing. But what I found after taking the amps out confused me a bit more, now I'm unsure if it's the amps or head unit that failed.

Things I experienced prior to amp removal:
- Head unit turns on fine, presets work, antenna goes up, no buzzing/noises coming from the center console or head unit knobs.
- Center speaker had a faint static/crackling noise that generally got more noticeable by increasing volume. Door speakers had no sound at all.

After amp removal:
- The driver door and subwoofer amps look original. The passenger amp has a date on it marked 12/2/03.
- Not sure if only the passenger amp was replaced at some point or if they all were, and if they were, is it a problem with the head unit.
- A blue connector that I found in the foot well, looks like it connects to the blue thing on the metal plate, but it leads nowhere.

Either I figure out if the speakers are still good and the head unit is bad, and depending on cost get an oem replacement or double din unit, or if the head unit is fine and the amps just need repair. Any additional insight would be appreciated.

Driver door amp:


Blue connector in foot well:


Sub, driver, and passenger amps:

Sure sounds like the head unit since it would be strange for all amps to go out at the same time but its not impossible.
You could jumper a small speaker or a pair of lightweight headphones to the head unit output (at the input conn to the door amp) and see if you hear an audio signal. That would tell you if the head unit is working.

bullithollywood said:

Sure sounds like the head unit since it would be strange for all amps to go out at the same time but its not impossible.
You could jumper a small speaker or a pair of lightweight headphones to the head unit output (at the input conn to the door amp) and see if you hear an audio signal. That would tell you if the head unit is working.

Click to expand...

It's not that unusual to have all the amps gone as people don't really understand the BOSE "dist'd amp" design and they can appear to be very expensive to replace if you just approach a dealer. Prime User BrianK can fix them for you for a very reasonable cost. Having owned an NSX and been on the site since 2001, it's my belief that 80-90% of the time it's the amps, not the head unit .. but Brian also fixes those. The head unit is considerably more difficult to diagnose since it has separate circuitry for radio vs CD and I wouldn't think that the symptoms that datvince described are necessarily pointing at the head unit. The crackling from the console speaker might suggest that the sub amp is shot but there's still that 10% chance that it could be the head unit. The suggestion above about connecting headphones to the amp is a good one but you'll also have to figure out which are the +12 and Gnd wires .. and which are the +/- of the audio pre-amp output. Sorry .. I don't remember the colors but I'd guess that +12 is probably black or something with a black stripe; Gnd is prob Green or maybe white. The audio is prob one of the colored ones like purple.

The question you didn't ask is "how can I replace the OEM system with aftermarket?" Part of the problem is that you'd be going to a centralized amp design so you'd have to bypass the door amps if you wanted to continue to use the door speakers as-is in their enclosures. If you want to keep the OEM head unit, then you'll have to find a place for the amp .. which is typically in the trunk or behind the driver seat. The good news is that SOS makes adapter cables from OEM head unit to aftermarket amp. If you want to replace the OEM head unit with an aftermarket one with built-in amps, then you'll have to deal with the double-DIN size in the console .. and also bypass the door amps. Remember that the door wiring was originally only designed for pre-amp levels and is a light gauge so if you're thinking of replacing door speakers and powering from new high power amps, you could have an impending meltdown/fire on your hands.

Check the power amplifier relay in relay box 1, under the hood. If it's dead, the amps will not energize. Read through this thread for more: http://www.nsxprime.com/forum/showt...-the-amp-relay-I-read-about-in-the-NSX-manual

Thanks for the input. Not too familiar with electrical systems, so I'm not sure how to directly connect headphones as you guys describe.

clean_green, I did pop the hood and find the relay pointed out in that thread. Visually there was a little dust on it so I removed it, blew it off, and put it back. I hooked up all three speakers again and tried turning on the radio, only to find now the antenna doesn't go up. I also take back my previous point of the door speakers having no sound at all. There's a really faint hissing when I turn the head unit on. I feel like it is just the amps that need repair, but now after removing/putting back the relay, the antenna doesn't go up anymore. I'm hoping I didn't add insult to injury and break something else.

Power amplifier relay:


Found a diagram on Acura of Oakland's (SF bay area) website where I can get a replacement relay if needed for about $40.

Looks like you've had one new amp in the life of your car, if the others have not gone now they will at some point. May as well get them serviced now while they are out and have many years pleasure from them.
My head unit has just died totally, will give it to Kaz to work his magic on. Probably the same old leaky caps...

datvince said:

Thanks for the input. Not too familiar with electrical systems, so I'm not sure how to directly connect headphones as you guys describe.

clean_green, I did pop the hood and find the relay pointed out in that thread. Visually there was a little dust on it so I removed it, blew it off, and put it back. I hooked up all three speakers again and tried turning on the radio, only to find now the antenna doesn't go up. I also take back my previous point of the door speakers having no sound at all. There's a really faint hissing when I turn the head unit on. I feel like it is just the amps that need repair, but now after removing/putting back the relay, the antenna doesn't go up anymore. I'm hoping I didn't add insult to injury and break something else.

Power amplifier relay:
View attachment 124110

Found a diagram on Acura of Oakland's (SF bay area) website where I can get a replacement relay if needed for about $40.

View attachment 124111

Click to expand...

Try swapping the relay out with another in that same bank. They are all the same so it's cheap trouble shooting

That amp in your photo looks good (doesn't mean it is good though)

The blue connector is a service connector, it locks into the dummy connector at the top of the cover.

The easiest way to check the relay is to see if you have battery voltage at brown connector yel/red wire with the head unit turned on. ( preferable with the speaker connected and loading the circuit)


Sometimes the radios are repairable, but most repair guys say it cant be done. I think it really comes down to how much time they want to invest, The ribbon cables go bad, they are not available. It took me about 4 hours to repair all the damage to the main board on my oem unit. It can be done though.

If you want to stick with oem speakers and new amp, you can also check out Willmans electronics, he has brand new enclosures complete amps, speakers, enclosure for about $250.00 each.

Thanks for the input everyone, I know this topic is a common one beaten to death. I have voltage at the relay, and I can also hear the click when I power on the head unit. To my previous point of the antenna not going up anymore, it was due to me removing the door light fuse since I had the doors open when removing the speakers. Makes sense since the antenna is probably powered by the same wiring that powers the trunk light next to it.

I just shipped the amps to Brian today. Hopefully I get sound when they come back, I just wanted to see if I can eliminate other possible points of failure. Again thanks for the help everyone, really appreciate it. I'll make sure to follow up once I get the amps back in there.

bullithollywood said:

Sure sounds like the head unit since it would be strange for all amps to go out at the same time but its not impossible.
You could jumper a small speaker or a pair of lightweight headphones to the head unit output (at the input conn to the door amp) and see if you hear an audio signal. That would tell you if the head unit is working.

Click to expand...

Just did this (actually on the bench with a 12-volt power supply and an antennae plugged in) and it was easy to verify that both channels were indeed working. The wiring diagram is on a label right on the head unit. Piece of cake.

I got the amps back from Brian today, put them back in the enclosures, and hooked them all up. Turned on the head unit and still no sound, but the high pitched buzzing I mentioned in the first post is gone from the center speaker, and there's a feint hiss from all speakers which according to Brian should be normal. So now it looks like the head unit is the culprit. Wavey, I did go through your thread to get a better understanding of testing the head unit. I've removed the center console so the head unit is ready to take out, do you or others from this thread mind posting pictures of how you set up this bench testing? I do have an older set of speakers that have wires I can plug into the head unit output using that diagram underneath. I've done some googling/youtubing, and some people have wires going to a computer PSU and some directly to the car battery.

After all that effort though, is Willmans my only option for repairing the head unit? I know I mentioned replacing it, but I understand everyone's point that it will involve changing everything else. I just want to hear the original sounds of the 90s : (

Mine is back together and I didn't take any photos. But it's pretty simple to locate the + and - pins, correct pins for the L/R channels etc., and to make jumper wires. The output from the radio is pre-amp, not sure if it would drive a full-sized speaker? I had a little speaker that came out of a small radio and could hear the output fine. Also had an old antenna on the shelf so that was easy.

But it's almost for sure your head unit is bad at this point. Last time I talked with Daryl Willman (two weeks ago) it sounded like he was not going to do any more head unit repairs, and Brian K doesn't do them anymore. But there are two other shops referenced tin this thread:

http://www.nsxprime.com/forum/showt...ess-for-over-50-years-I-think-we-know-a-thing

and someone had a good experience with a shop in LA (I'd have to search for that one). You might try one of those.

If you can wait a week or so, I can update you on whether my local (Chicago) shop is able to fix these babies.

After all these weeks one more won't hurt haha. Sounds pretty promising. That shop in LA sounds like a good place too and is a little closer. I'm doing some more digging to find a local place as well (I'm in the SF bay area). Thanks for all the replies everyone, it really has been helpful being new to the car and its little surprises.

Does anyone know who can fix the tape mechanism in the head unit. I just installed a used head unit for the time being but the condition is not as good as the failed unit. I had a cassette adapter for mp3 get stuck in the head unit and the culprit is a piece of metal that got jammed and broke for the cassette to eject.