How to Modify the Stock Fiero Radio for MP3 Players, With Pics. (Page 4/7)
texasfiero MAY 13, 12:06 AM

quote
Originally posted by Ratfart:

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.


My radio lives here: http://rnew.lonestarfieros.org/cdplayer.html

[This message has been edited by texasfiero (edited 05-13-2006).]

fierohoho MAY 13, 11:52 PM
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).]

30+mpg MAY 14, 12:00 AM
Only 3 wires left to solder. (5-2=3)
fierohoho MAY 14, 12:04 AM
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).]

fierohoho MAY 14, 12:07 AM

quote
Originally posted by 30+mpg:

Only 3 wires left to solder. (5-2=3)




Don't tell me you waited up for this.
Jncomutt MAY 14, 11:28 PM
Nice write up, thank you...
fierohoho MAY 15, 10:24 AM
OK, kinda stumped.

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.

Jax184 any thoughts?
Jax184 MAY 15, 10:34 AM
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?
cjgable MAY 15, 10:53 AM
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).]

fierohoho MAY 15, 11:26 AM
Ok another update from my failure.

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.