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Audio/Electical folks: No sound from McIntosh stereos...not solved...


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02 H6 McIntosh. Need some audio/electrical folks. Had this car a long time and have never been able to figure this out. I've already checked fuses, swapped speakers, amp, fuse, stereo's (3 times). The hardware *seems* ruled out, time to start tracking...

 

How many items are plugged into the back of a McIntosh stereo - is it three: antenna, amp cable, and normal Subaru connector?

 

Swapped in 3 different McIntosh stereos and none have any sound.

Swapped in another amp and rear speakers (I already know the fronts work).

 

I guess I need to test for power to the amp - It's supposed to get 12 volts I assume?

 

Can I test for an output signal from the headunit to the amp....what kind of voltages are those unamplified signals? Is there any access to the metal pins, those are some tiny round DIN connectors or whatever they're called, not sure I can get a multimeter pin on the pinouts?

 

Or any other way to test a McIntosh stereo besides plugging it into a car (which I'm not sure is properly functioning to begin with).

 

With a WRX 6 disc changer installed the front speakers work fine, just like any other Subaru, that's what I've been using for awhile.

Edited by grossgary
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The McIntosh system relies on an external amp to power the speakers.

If the amp has no power then you get exactly the situation you describe. Head unit powers up but you get no sound.

 

FSM says the amp gets power from SBF 8, with another 20 amp fuse inline to the amp. The fuse is in a "relay block" under the dash to the left of the steering column. There should be 3 or 4 relays in the block. They are the ignition relay, DRL relay, power window relay, and wiper de-icer relay (if equipped).

The line splits after that and you should get 12V on pins 1 and 7 (red/black wires on both) of the amp connector.

Pins 10 and 11 are ground. Ground wires should be black.

 

The only input signal wire I see on the wire diagram is a DIN cord. The amp then splits out the signals to all speakers and the subwoofer.

 

There are 4 other outputs from the head unit it appears, and they aren't labeled as speaker outputs but two of the connector codes match up to the front door cords. This could be why the front speakers work.

There are two outputs that appear to end in the dash, perhaps this could be the rear channel and the wiring to the back was not put in at the factory?

Edited by Fairtax4me
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Good info from Fairtax4me. Like he stated, verify the amp is getting power to pins 1 and 7 that comes from the fuse in the relay block. If you have no power then the fuse is most likely bad. One other possible issue not mentioned is the control signal wire from the radio to the amp. Look for a green wire going to the amp. When the radio is on I think there should be 12 volt power on that lead to turn the amp on.

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I can't find anything wrong. at the amp:

Pins 1 & 7 both have 11.20 volts.

Pins 10 & 11 both have continuity to ground.

So headunit and amp all have power/ground.

 

THREE different McIntosh stereos all act identically.

TWO different amps, using all three stereos with each one, no change.

Any other Subaru stereo and I get sound out of the front two speakers.

 

I can't verify the amps are coming on or doing anything though. They have power and ground but there are no lights or anything at them.

 

So - how to test the amps?

 

When I first install each headunit the LCD flashes "SYS"...I assume just because it was plugged in. Push the ON button and they all operate the same.

 

* But maybe this SYS message indicates something else?

 

So:

1. I'm missing something

2. Both amps are bad

3. All three headunits are bad

 

Amps seem most likely....so how to test/verify they're doing anything....I'm going to pull one apart and see if I can find a fuse in it...

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Look for a green wire going to the amp. When the radio is on I think there should be 12 volt power on that lead to turn the amp on.
There is one light green wire...no voltage to it.

 

Can someone verify if there's supposed to be a "power on" wire to the amp and which one it is?

 

I'm going to try to take one amp apart and see if I can find a fuse inside of it.

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*Solved* finally! Thanks guys for the tips and pin outs! High five!

 

I disassembled the amp and there's a 25 amp fuse soldered to the board. I assume the other amp will reveal the same.

 

I'm going to solder wire to it and mount a fuse holder externally on the case.

 

Questions:

1. Any tips for soldering wire/mounting the external fuse?

2. There's one crusty diode - can I test that via continuity - in one direction right?

3. Should I spray the board down with anything...cleaner...etc?

 

I'm not fixing the board only to have the fuse blow immediately and have to disassemble it all over again. I'll mount the fuse externally on the side of the case.

 

It is obvious that being under the seat it not ideal. There is dust and debris galore and one of the diodes appears crusty on each side. I've got kids so he back seat area gets well used.

 

Owners with amps (and kids LOL) may want to be sure to keep it clean, dry, and dust free under the passengers seat.

 

Thank you much! Looks like I may finally have this McIntosh system up and running soon finally.

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I am fairly certain the green wire is the control lead from the radio to the amp to turn on the amp when power is applied to the wire. If you don't have voltage on that lead when the radio is turned on then check the other end on the radio and see if you have voltage on that end. If you have voltage at that end then there is a connection problem somewhere with the wire.

 

You can check the diode by using the diode function of the meter. One way will show no continuity and the other way should show you the forward bias barrier voltage of the diode.

 

To see if you have signal coming from the radio you should be able to use your meters AC voltage function on the millivolt scale to watch for voltage changes of the audio signal. Tape some stick pins to the probe tips if you need a finer point to test with.

 

I don't think you need to clean the board unless there is some severe corrosion on it. If you install an external fuse I suggest you one that is sealed so moisture can't get to.

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It would be a good idea to check the resistance of each of the speaker leads to make sure they aren't shorted together or to ground. A short on one of the speaker leads could very well be what caused the internal fuse of the amp to blow on both amps. Check that sub-woofer.

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It was not a confirmed good amp so I don't know if the car "caused" both or not.

 

Car was wrecked and I bought it as a totaled salvage vehicle 70,000 miles ago. I rebuilt it, drivers side door needed replaced so could be that the wreck caused it to blow.

 

The diode is so tiny I can barely tell what's going on, just some fluffy stuff around the ends that connect to the circuit board.

 

I did solder an external fuse yesterday and got nothing...but I did it rather quick.

 

I'm going to disassemble the second amp. I'll post pictures of any questions I have, I've never really repaired a board before. My soldering iron doesn't actually de-solder the solder on a circuit board...but it works fine for the solder I have.

Edited by grossgary
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Did you check the green wire again for power when you replaced the fuse. I suppose that power could come from the amp and the radio completes the circuit to turn the amp on? I doubt that is the way it works but it could be done that way. All the control leads I know of place power on the wire coming from the radio to turn on the amp. Even though you replaced the fuse in the amp it needs to be turned by a circuit in the radio.

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Did you check the green wire again for power when you replaced the fuse.
No...are you positive it's the green wire? And it's a constant 12 volt source? Could it be a momentary switch type signal?

 

It had no voltage the first time I tested it (before attempting the repair).

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No...are you positive it's the green wire? And it's a constant 12 volt source? Could it be a momentary switch type signal?

 

It had no voltage the first time I tested it (before attempting the repair).

 

After looking at my data again it looks like I made an error. The green wire goes to the amplifier for the antenna and not the PA. Sorry about that. The only other place the control lead can be is inside the din cable and the data doesn't break those connections down. It is just a solid line between the radio and the amp. See if one of the connections of the din plug has power on it while the radio is turned on.

Edited by Cougar
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As usual with electronics I guessed wrong...I disassembled the second amp and the internal fuse is fine. The board looks immaculate compared to the other, nearly new looking.

 

So - I have one amp with a blown fuse and another amp with a good fuse.

And of course a non-working McIntosh system.

 

So either the second amp is bad or something else is wrong.

 

Is this amp "always on" or does it "get turned on" by the headunit?

What next?

Anyway to test an amp?

 

Does anyone know how that weird DIN connector is supposed to attach/detach, is there a trick to those, they are a very weird connection and make no sense...some strange ring that's threaded looking, but it doesn't thread into anything and the connector feels/appears clipped in but no obvious way to unclip it.

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Here is a link to some info that can help you out. It looks like the turn on control lead for the amp is on pin 5 of the DIN plug which would be the top pin in the middle row of the DIN connector in your picture if I understand it correctly.

 

http://www.subaruoutback.org/forums/69-audio-video-security-navigation/4426-pinout-13-pin-din-amp-connector-mcintosh-hus.html

 

 

Here is another link with a lot of more good info.

 

http://forums.nasioc.com/forums/showthread.php?p=10308977&postcount=12

Edited by Cougar
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