Stereo Receiver Replacement Fail . . .

[tpenfield]

After 21 years, the original stereo receiver in my Formula 330 crapped out . . . can you believe it

It is a Kenwood KRC-901 with a Kenwood KDC-C603 CD Changer and 2 Kenwood KAC-425 power amplifiers.

I figured on staying with Kenwood for compatibility, etc. and got a new Kenwood KMR-M318BT receiver. . . the thing does everything but open beer cans.

Anyway I figured that it would be pretty straight forward to replace the KRC-901 with the KMR-M318BT. I have never used the CD changer, and the plug for the CD changer, did not match up size-wise to the expansion port connector on the new receiver. New receiver has a smaller connector . . . looks like fewer pins.

I get the new receiver hooked up and connect it to the audio cables to lead to the power amplifiers (front & rear). . . NO Sound :facepalm: . . . I read through the manual . . . nothing helpful. Not sure if it is the receiver or the power amplifiers. :noidea:

I'm a little bit out of my league here, since I hate hooking up audio equipment (they make it sooo confusing . . . ) Looking for some guidance. :hail:

I was thinking maybe it is as simple as a mute button or function being on . . . I cannot find any such thing.

Then I'm thinking . . . maybe the CD changer has to be connected some-how in order for the power amplifiers to power up. Does not seem feasible since the old vs new connectors are different.

Just not sure how to proceed

T.I.A. for any guidance or wisdom.

 

[briangcc]

I'm assuming that you used RCA's to connect the head unit to the amps correct? If so, they do sell adapters that will take a standard headphone jack and convert it to RCA. Provided you have a cell phone that still has a headphone jack what you could do is plug the adapter into the cell phone and then connect it directly to the amp. Now you can test to make sure the amp is still working.

Provided the amp is working, the next step would be to connect one amp to the head unit and retest. Do you have sound? if not, is there something in your manual to turn on the sound to the RCA ports? I wouldn't think so BUT every head unit is different. I have a Pioneer that when I put power to it after sitting unplugged I have to go into the menus and enable the external input. Weird but that's how its set by Pioneer.

If you get sound from one amp, now try the same tests with the second amp.

And the above assumes you are able to power up the amps when you turn on the head unit. This is normally a blue wire that you would run from the head unit to the amps. I pulled up your manual and it appears this should be the blue/white wire coming out of the pigtail.

Good luck!!

 

[josh_booth]

Some amps have a remote wire plus the audio cables that has to be hooked up to the receiver. If there's a small wire with in the rca cables look at the wiring diagram for the receiver and hook it to the wire called remote, most of the time its blue or blue with a white stripe i think, it's been 10+ years since I've wired a stereo system

 

[tpenfield]

Thanks, guys. I hooked up the new receiver with the same wiring connections as the old one had, namely:

Yellow
Black
Red
Blue/white

The 4 pairs of wires for directly connecting the speakers to the receiver were not used on the old receiver, and I did not use them on the new one.

The old receiver used the RCA connectors to connect to the amp, and I did the same with the new receiver. The only thing that I could not connect was the expansion cable that led to the CD changer. Just looking at the documentation that I have, it looks like the CD changer only connected to the receiver, so I would assume that the receiver is doing all the 'talking' to the amplifier.

I'm going to take another look at things tomorrow to see if I can make some progress. It seems that I did connect the blue/white wire, and I'll see about the remote wire.

 

[josh_booth]

I'm going to take another look at things tomorrow to see if I can make some progress. It seems that I did connect the blue/white wire, and I'll see about the remote wire.

The blue/white wire is the remote wire, it's what actually turns the amps on. If it's hooked up I would move on to the amps to make sure they are turning on with the head unit, mine has a light on the amp when it's on.

 

[Baylinerchuck]

It sounds to me like the amps aren't coming on. I'm pretty sure kenwood has a power indicator for their amps. It used to be a triangle in the W. Anyway, if they are not on, check for 12v between the blue/white and black with the head unit on. Is this wire fused? Also check for 12v at the amps power terminal to ensure it's getting battery power. The amps have to see 12v on their "remote" terminal in order to switch on even though they are powered from a constant 12v supply. You can force the amp on by jumping across the +12v terminal and the remote terminal of the amp with a short wire. If the amps are on then you may not be passing audio out the preamp RCAs. I don't see a setting for these outputs in your manual, which is pretty standard. Hopefully you didn't get a dud.

 

[tpenfield]

Here are a couple of pictures/diagrams of the installation that I did, as best as I can tell

the original OEM installation




Then the new installation. . . . I did a 1-for-1 change-out on the wiring at the main connector, since the new connector was slightly different that the original connector

The only other difference is the 13 Pin DIN going from the Receiver to the CD Changer is not connected, and I am wondering if that is where the amplifiers are getting some sort of power switch signal.



The only other wires on the "New" Main connector are a Blue/Yellow (Steering Remote) and a Brown (Mute) Both of those are not connected.

I should also mention that the original Receiver had a motorized cover that retracted on power-up. that became intermittent with age and would not come on intermittently. Otherwise the old system worked as always.

I'm going to take another run at things this morning . . .

 

[Scott Danforth]

Your amps should also have a red power wire, a black ground, and a blue remote wire. Make sure you have voltage at the amps on both the red and blue wires

 

[tpenfield]

Your amps should also have a red power wire, a black ground, and a blue remote wire. Make sure you have voltage at the amps on both the red and blue wires

Thanks, Scott.

FWIW - I checked the sizing on the DIN connectors . . .

The original Receiver has a 13 pin DIN

The New one has a 10-pin DIN.

I'm going to check the pre-amp outputs for an audio signal and see if I am getting power to the amplifier connectors.

 

[sam am I]

...

 

[tpenfield]

Update: SOLVED . . .

I did some probing around the wiring with my multi-meter and tested the Receiver for pre-amp output at the RCA jacks. Those were fine.

I did find that there was a bad connection in the house wiring of the Blue/White wire. That wire is connected at a butt connector to two wires that feed each of the '425' Amplifiers. I has getting no connectivity from the connector at the Receiver to the same wire at the connector to the Amplifier.



The connection at the butt connector was probably marginal and my tugging of the wires during the installation process probably made it fail. So, I re-worked the connection and the system sprang to life.



I may have to adjust the input level, as I noticed there is some sort of switch on the '425' Amps. They are hard to see/access because they were installed in an awkward location within the closet in the cabin.

It works !!!



The set-up allows you to change the color of the display in minute increments, covering just about every color in a rainbow. Not sure what the value of that is :noidea: Purple will due for now

Of course, now I have a better understanding of the wiring and how it all works

Power and ground are delivered via the Yellow and Black wires. The switch at the electrical panel in the cabin puts power to the Red wire, which turns the Receiver on.. The Receiver (Head Unit) once 'on' then puts power back out to the Blue/White wire(s), which turns on the Amplifiers.

:ranger:

 

[tpenfield]

I made an adjustment of the Amplifier's input sensitivity; seems to better match the head unit volume control. Thanks, everyone for your help on this. :thumb: