...where Jax184 mentioned he had modified his stock GM radio so an MP3 player could be plugged into it to play over the car speakers without one of those FM Transmitters we traded a few PM's and this thread is going to be me posting pics and him walking me/us through this modification.
I will first post some pics of the stock radio I took out of my 84SE.
The front of the radio.
The passenger side.
The rear.
The drivers side where I believe the Amp board is located that we need to access.
------------------ Where will the road take you today?
This is the 1/8" stereo bypass jack I found at an electronics surpluss store.
When you plug a stereo headphone jack into it it will stop the signal from going through it and allow a new signal to go through it in its place.
This allows the MP3 player to use the Amp from the radio to send a clean signal to the speakers.
OK, now it's Jax184's turn, what do I need to do or take apart now?
Jax184, as I have the equilizer controls on the front of the radio I am limited as to where I can put the stereo jack, I'm OK with putting it at the back as there seems to be room there or maybe I'll even do a remote mount.
[This message has been edited by fierohoho (edited 05-10-2006).]
Cool write up so far ( I like the pictures). I will try this with one of the newer Pontiac radios that I have. This is also a good time to rplace any burnt out bulbs, you can get the grain of wheat bulbs at Radio Shack
------------------ Signature courtesy of MinnGreen.
[This message has been edited by Fiero STS (edited 05-10-2006).]
If you look at the amp board, you will see a series of white wires held into a strip with a piece of masking tape. Two of these wires carry the raw unamplified audio signal from the tuner/tape mechanism. Simply look to the tuner board, where they connect, and you will find an "L" (Left channel audio) and "R" (Right channel audio) written next to the wires you want.
Next you carefully unsolder these two wires from the amp board. Pull them from their tape backing, without mixing them up. These two wires will go to the headphone jack, so that they will be connected when nothing is plugged into the jack.
After that you need to solder in two short wires between the jack's output lines and the amp board.
But wait, I hear you ask, how do I know which pin is left and which right on the jack? Well, if you have a volt meter, it's pretty simple to figure out. Set your volt meter to ohms (to show when a connection is made) and plug that short length of audio cable into the socket. Now touch one line of the volt meter to the very tip of your audio cable's connector, and find the pin that shows power on the jack. Ta dah! You just found the left channel, and what gets connected to the "L" solder point on the amp board. Repeat the process with the middle part of the audio cable's connector.
Once you know which pin is Left and Right on the jack, you'll need to also find out which pin is Left and Right on the jack's passthrough. So unplug the audio wire and, using your volt meter again, find which pins show a connection with the L and R pins you already found. These are where you attach the two wires from the tuner board.
Alright, almost done now.
You might notice about now that there's one pin on the jack that we havent used for anything. This is the ground pin, and must be connected to the stereo's ground somehow. There's many places where this can be done, as it's all a common ground. I'll leave it up to you to decide where to solder the ground pin to, but I simply soldered it to where a nearby screw went into the metal frame.
After this you need only mount the jack. On the radios that lack an equilizer, there is a perfect gap between the display and the volume control. You can see where http://www.jax184.com/pictures/car/IMGP2917.jpg (Yes, that's my radio) To mount here, you only need to find the gap in the metal framework, and drill a jack-sized hole infront of it. Then glue the jack to the framework.
Radios WITH the equilizer will need to find another place. I've not done this to one myself, but it looks like there may be a spot directly above the LOUD button.
Note that having the jack on the back of the radio would be a bad idea. You'd need to dig around behind your radio surround every time you wanted to switch between using the radio and whatever you have plugged in. Not fun.
Now you just need to reassemble the panels and put the radio back in. Congratulations, you've just brought your Fiero's stereo into the 21st century.
If any of you arnt comfortable with performing this modification, but would like it done, I'd be happy to do it for you. Simply mail me your radio with return postage and a few bucks to cover the work, and I'll have it shipped back out in a few days. Email me if you're interested.
this is fantastic. I'm kind of a purist with my Fiero and would love to get back to the factory stereo and still have my music. My son will get the blaupunkt mp3 unit!!
Great idea and writeup. I did something similiar to my truck. I used a rocker switch instead of the disconnecting receptacle. I didn't even know about those at the time. I think I'll redo it. BTW did you get the receptacle locally?
[This message has been edited by cjgable (edited 05-11-2006).]
Have been reading with interest, my Pioneer AM/FM/CD took a dump after 3 years in the car, have this waiting in the wings to possibly go back in, with the mp3 conversion.
This will take an input from any common audio source.
As for newer radios, it should still be doable with some fiddling. Again my offer to do the modification myself comes into play. I've figured out how to make crazier modifications in the past, so I don't mind giving it a try.
Jax are you on the local email list. A few people were interested in something like this. So I am sure this thread will be of great interest to more than a couple of local people.
------------------ 85GT 5spd ,93 Eldorado 4.9 Dual O2 Custom Chip, Archie Clutch. Custom Exhaust. MSD Everything 245/50/16's Cant wait for Dyno Time and Track Results. Not Your Average 4.9 Capt Fiero Com --- My Over View Cadero Pics Delta Cam and Allante Intake Soon.
MIGHT not be an issue, but you possibly will want to use shielded cable (something like you'd find used for your headphones) to run from the jack, to the audio input stage of the amp.
This will reduce the chances of any interference/hum being picked up from the various components your wire will probably have to run near.
No point in going to all that trouble just to have it sound crappy!
Ok, I had time this evening what with work and being a little under the weather to go out and locate and get a pic of the L & R on the Amp board.
My last pic was correct for the taped ribbon of wires that hold the L & R wires.
This pic is from the other side of the board and I have labled it and put a red tracer on the L & R wires, you can easily see the L & R on the board, OK I used a magnifying glass but I could at least see it then.
Next question for Jax184, if I read your post right the 1/8" stereo plug is set up this way and I would guess this is universal to all stereo equipment.
As for the shielding, you'll notice the rest of the stereo's wires arnt shielded. I never noticed any noise problems myself, but my stock speakers sound as though they've been knitted...
Can you show a picture of you actually doing the soldering/unsoldering?
I have no experience at small electrical board soldering. I can solder wires, pipe, cast iron....etc...you name it. But I have never soldered something this small. I would be a little leery of burning the whole board up. I'd like to see if there's any special soldering iron/gun you use.
You use a pencil-type soldering iron of roughly 25 watts. Like http://www.allerc.com/images/Pictures/SOLDERIRON.jpg if you've never seen one. The finer the tip the better for this. You also use very fine solder. Again if you don't feel that you can safely do it, I could do it for you.
Has anyone looked into the what the original signal level is at the point the aux jack is being wired into? I wonder if it is a low level signal and if the mp3 player would be overdriving it. What about impedance matching? Is the Pontiac amp section a voltage controlled device or does it require some current? I don't think it would have a FET front end in the 1980s' but I don't know. Just thinking.....
Has anyone looked into the what the original signal level is at the point the aux jack is being wired into? I wonder if it is a low level signal and if the mp3 player would be overdriving it. What about impedance matching? Is the Pontiac amp section a voltage controlled device or does it require some current? I don't think it would have a FET front end in the 1980s' but I don't know. Just thinking.....
I asked Jax184 that question in a pm. Here's the answer:
I've never worked on one of those radios. You could tear into it though and see what you find. Or as I said in my post, mail it to me and I'll take a look.
The output of most MP3 players and the output of the radio is a little different, but it just takes a bit of fiddling with the volume of both to make it work just fine. I had no problem using an iPod with my radio after I modified it. I'd turn it up with my doors and sunroof open while working on my blown head gasket.
----- Original Message ----- REALLY GOOD INFORMATION! I have a '97 Grand Prix radio in my '86gt as well as the wife's '97 Grand Prix. I'd like to add an input for mp3 to both of them. I have the tech. ablilty to do the work but don't know the connection points.
'Nother question. The signal from the mp3 player is amplified for head phones. Is it strong enough to cause distortion, or should I worry about it. I used to use an attenuator cable with older decks when going into preamp.
Well I got some time Saturday night to finish the radio modification.
I first soldered five wires to the jack.
After much thought I found the only place to mount the jack in my radio was to the right of the cassette slot.
This required I modify, (ok cut), the metal frame of the radio.
I then fed the wires down inside the right side of the radio and between the circuit boards to the Amp side.
I removed the left tuner wire from the circuit board and soldered the left output wire from the jack to the circuit board.
I then soldered the left tuner wire I had removed from the board to the left tuner in wire from the jack and I covered the connection with heat shrink tubing.
I did the same thing for the right wires and after that it was time to put er back together.
[This message has been edited by fierohoho (edited 05-14-2006).]
Due to my jack having a fairly short mount thread I had to mount it to the radio face which is plastic and that meant no ground for the common on the jack, this meant I had to include a ground for the common and that's the green wire you can see in the pic of the jack with the wires attached, I ran that to a screw on the frame of the radio and grounded it that way.
With some real careful measuring I made the hole where the jack was to be mounted in the radio face, covered the exposed pins and wires on the jack with electrical tape and started putting the radio back together.
Here's a pic of the radio back together with the cord that would go from the radio to the MP3 player plugged into the jack.
Had I not been able to mount the jack in the radio's face I would have used longer wires and mounted the jack inside the center console most likely under the ashtray.
When I get it installed in the car I'll test it out and let you all know what I think and whether or not I goofed up or broke the radio when I had it apart.
Oh and I'll have pics of it installed too.
[This message has been edited by fierohoho (edited 05-14-2006).]
I installed the radio this morning, worked fine as far as the AM/FM, all speakers going strong, plugged in my ipod and the radio station I had on cut out, so far so good, fired up the ipod and...nothing.
Checked the ipod and all is OK there.
Pulled the radio and rechecked the wires, all appears OK, no shorts, wires hooked up correctly.
The only thing that went wrong was I blew the radio fuse at one point plugging in the connector from the ipod to the radio.
Replaced the fuse and back to radio works but no ipod through the speakers.
Now that's an odd one... I've never blown the radio's fuse with connecting the iPod. I did notice that I needed the volume up fairly high though to compensate for the small output of the iPod.
Are you sure the ground line isnt contacting anything else?
I am not familiar with the grounding on the stock radio, but would the ground from the jack work better connected to the audio ground on the circuit board? Maybe next to the R&L connections? Just a thought.
[This message has been edited by cjgable (edited 05-15-2006).]
I did check the ground wire for possible shorts but found nothing, played with the volume on both units and nothing.
Tried it again after the bench check for shorts and correct hookup of the wires and I noticed that when I plugged in the ipod the Stereo indicator for the FM station cut out.
I did try a direct ground to the frame but nothing there.
Well next thing you know something musta fried as I now don't have any AM/FM at all!
I put the CD player back in, I'm admitting defeat at this point pending any new information from anyone.
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