Will's'74VetteL-82

Hello,

I have an old Alpine 7256 head unit in my 1974 Corvette. It was in the car when I got it, and seems like it may have been professionally installed back in the day (early 80's). I am currently taking apart my interior to POR 15 my birdcage and rebuild the vacuum system, and I figure I'll also do my dash speakers at this time, as I'm still "rocking" the originals. One thing I need help with is a cable that comes out of the head unit. It connects to the HU with a DIN connector, and has two RCA cables and two other wires that come out of it. It ran to the back of the car from the HU, specifically to the jack storage compartment. The two other wires seem to be spliced together into one wire, which seems to be a single wire type wire. I have done some research and it seems the cable should have a 4 port connector at the end for things like "remote", "accessory" and other things. Currently, there is no connector just the spliced wires.

Overall, what is this cable for? To my knowledge, it is for an amp connection, but what is the deal with the other wires coming out of it and no connector, but the splicing thing? Also, the car didnt have any audio accessories when I got it, so this cable ran to nothing, and it seems its been like that for a while, as the cable is busted up and rusty. The speakers were also connected using the HU speaker out wires, and wired very well with the original connectors from the speakers running into a bananna connector.



The Harness



The Connector that goes into the HU



The wiring harness Model number (alpine)



The three different types of wires



Three different wires (Blue, Brown, and RCAs)



2 into 1 wire splicing



RCA connectors to longer cable



Connect to RCA pre out - for an amp right?



End of the RCA cable, one connector is ripped off (this was in the jack compartment)



This is the end of the "2 into 1 wire" it was in the jack compartment, too.



Another view




Let me know if you guys have any ideas about what this is and what I can use it for (which i think its for an amp)- If I were to run an amp using this, would those other wires coming out if it be important?

Thanks,
Will

markcz

You can prob keep the pigtail end that goes into the radio, but I'd just ditch the rest and get new RCA's.

They are most likely the sub line-level signals on the RCA's. The blue/white wire on the din plug is most likely the trigger wire for the sub amp (has +12vdc when radio is on).

Not sure about yellowish wire.

v8rx7com

In the 80's both Kenwood and Alpine used DIN cables instead of RCA Cables to their radios and amplifiers.

Early Kenwood and Alpines equipment was DIN only for pre-outs and inputs (no RCAs) but by the late 80’s the DIN pre-outs were already going the way of the dinosaur in favor of RCAs, so a lot of the amplifiers of late 80’s early 90's era had both RCA and DIN inputs

The DIN cable was basically a single cable that housed the equivalent of a left and right RCA and a remote turn-on wire.

Your wires look like a DIY "do it yourself" spliced and modified DIN to RCA adaptor. I know that one of the wires in your pictures is likely the remote turn-on wire however I’m not sure what the other wire is for.... it might have been an alpine only thing (no longer needed).

Your timing is great because I was looking for something in my garage the other day and found an RCA to DIN adapter that I have from when I was a professional car stereo installer (years ago).

Funny ... when I found it ... I laughed … and thought to myself “what the hell are you holding onto this dinosaur for?”

If your not going to run an amplifer, you don't need any of those wires, If you want to run an amplifer, I can help

Here is a picture of the DIN to RCA adaptor I have:

Will's'74VetteL-82

Ok so it does have to do with an amp, and yeah that's what I'll do when I do an amp.

Thanks,
Will

Will's'74VetteL-82

Haha good stuff. I want to run an amp eventually, what kind of advice/info do you have for an amp install?

Also, I get the point of the RCA cables, but this talk of the remote turn on wire. If it it supposed to have 12v when the radio is on, I could ID that wire easily. But is it needed and what does it do, just turn on the amp when the radio is on, opposed to having the amp on all of the time?

Thanks for the info,

Will

markcz

Pretty much, yes. The amp gets it's power directly from the battery (with a fuse in the line), and should be grounded directly to the frame or an oem ground location. There is a third power wire terminal on the amp most commonly called a trigger. The radio puts out a +12v signal that is meant to be connected to that trigger so the amp is only on when it needs to be.

v8rx7com

Also, if my adaptor is the one you need, let me know, I would be happy to help you out.

Will's'74VetteL-82

Oh alright, that's good. I'll connect the radio and test that out before I do anything. Do you think I'll be good If the wire puts out the 12 volt when its on and none when its off, even though there's that weird splicing going on? Or should I take it apart and find out what each do?

Thank you very much, I'll let you know. Hopefully I can salvage the one that I have....I'll check its function soon, after I get my Windshield problems sorted out (my other thread).

Thanks,
Will

v8rx7com

I’m guessing the DIN Cable on the back of your head unit looks something like this picture:



Note: the head unit in this picture has both RCA and DIN, so it’s a newer model than yours (probally late 80’s).

Also, after looking at your pictures a little closer, it looks like they might have split the DIN signal into 2 sets of RCAs possibly to feed 2 amps. That might also explain the extra yellow wire (a 2nd remote for the 2nd amp).

If your DIN looks like the one pictured, the adaptor I have should work, and it would be a lot easier on you than trying to fix the existing harness. I can’t see it costing me more than a couple of dollars to mail it you. If you want, PM your mailing address, and I’ll send the adaptor to you and save you a lot of trouble. This way I will feel like I’ve hung onto it all these years for a reason (and get it out of my garage).

WAwatchnut

That is actually an Alpine adapter, #4095, not a homemade version. There originally would have been a white 4 pin moles connector at the end of the blue/whit and brown/white wires. Blue/white as mentioned should be the 12v+ trigger. Brown/white should be the "pause enable" lead (triggered external devices to pause, for phone integration IIRC).

Here's a link where you can almost see the schematics:

http://www.caraudio.com/forums/elect...a-adapter.html

You should be able to google alpine 4095 adapter for more info.

v8rx7com

The first picture on this thread, the harness looked to me as if it had been spliced and modified.

But now with the pictures you’ve found. I can clearly see that the harness he has should be fine.

Looks like Will (Will's'74VetteL-82) can just untape and remove the old RCA’s connected to his 4095 DIN harness. Then, connect new RCAs and extend the blue remote wire to an amp and he should be good to go

I didn’t think to Google the alpine part number clearly visible… good catch

Will's'74VetteL-82

Thanks for all of that info! I'll tear the old crap on it apart and get new RCAs and just use the trigger wire, not the pause wire. I had seen that picture before, so I had a sense of what it should be like, but it seemed more complex and since the diagram couldnt be seen well, I wanted to know more about it...which I now know thanks to you guys.

I'll see what I can do with my existing harness, but hold onto that other DIN to RCA harness....I may need it if something doesnt work with the one I have (Thanks for the generous offer, too)!

Will

v8rx7com

I’ll hang onto the harness …and if you need it, it’s yours (but I think the one you have should be fine)

Hats off to WAwatchnut,

I totally forgot about the phone mute wire

The phone mute wire lowered the volume on the head unit when you received an incoming call on your car phone.

I use to install car phones .. so I should have remembered the phone mute wire.

But then again, it’s has been over 20 years since I installed a car phone… Hell I can’t even remember the last time I’ve even seen a car phone.

anyway ...you should be good ... so I'll shut up now

WAwatchnut

I guess I'm showing my age... I remember buying those adapters for installs when I had my store... I actually remember how "home made" they looked, but at least they had the zip tie on the two single wires to relieve some stress.

Will's'74VetteL-82

Hahaha, car phones! My friends 1985 Mercedes Disel has one, it's pretty cool stuff (Of course, it doesnt work).

Thanks for all of the help on this matter. I have to plan about what I'm going to do with my stereo rebuild, because I have to figure out my windshield situation first. I'll let you know how it comes out.

Will