Pontiac GTO Forum - View Single Post

Ronin GTO · 05-29-2008, 06:05 AM

Quote:

Originally Posted by exwrx

There are no pin accommodations for an aux. That may not mean that the board itself wouldn't be capable of supporting one. Board-sharing, like platform sharing is pretty common in radio's from a given mfg., and the top most bar usually has 3 pin sections. The first, going left to right looking at the back of the deck, is a CD Changer section, usually accomodating a power source, and data pin. That one can't be used for an aux, or rather is beyond my abilities (Minor in Engineering, Major in Philosophy, Doctorate in pissing off the competition). I'm sure you could make some interface that communicates properly with the unit, converting an audio feed into the proper data signal, but it seems excessively difficult considering the other options available. It is theoretically possible to have control over the mobile device from the radio if the interface could communicate both ways. It is after all a 2-way data system, as the Changer would take commands from the deck, the deck then receiving audio data.

The middle plug/cluster of the top row, is the phone pin cluster, it has a AF+, AF- and Remote ground. I'm not sure whether the remote ground wire could trigger voice in mode, or is a ground for the unit attached to it when in voice-in mode.... similar to an armed ground on a alarm. I didn't check when I did my install. I was too excited to get it going and yank the Drive and Play. I do know that it's not a resting/constant ground, meaning it reads a low voltage when the radio is on/plugged in.

The Right plug/cluster of the top row is a direct aux in. It's a 3 pin in, L+, R+ and a shared -. Now there are no pins for the left, or right section on the back of the radio, but that may not mean that the AUX board/soldering points aren't there.

I don't know if I'd want to take it apart though. It would defeat the purpose of this install being a DIY. As is, I can still pull the radio and bring it to the dealer without any issues if it were to fail, or need service. I wouldn't have that option if I pulled/modified the board. These other options would be worth exploring on vehicles that have the pins readily available. My neighbor owns a porsche clinic/shop. Maybe I can get him to let me look at some of the decks. I know he's really interested in this aux-in mod, as many of his customers ask about something like this. I'll also look for some BP radio's at my old shop. I might be able to borrow one for a few days and see/check out the other pins. For now... we'll just say " to be continued...."

Just FYI, there is another way to add an Aux-in that requires some minor soldering to the main board. This is done with 4 small wires with capacitors (2.2uf polarized) connecting to 2 seperate areas on the board that coincide with the onboard chip. While your install does seem much more simple, I'm curious as to how it sounds. My only concern is that the source wouldn't come through in true stereo. I say this because the phone input is only mono but you seemed to have tapped into the actual H/U itself.

I've attached some rough diagrams detailing how the internal mod is done. Note that it requires an 1/8" switched jack that you can buy at Radio Shack. 5 wires will come from the jack (2 positive, 2 negative, and 1 ground) and 4 of them will terminate with a 2.2uf capacitor (2 will be positive, 2 negative). The other end of the capacitor will be soldered into the points specified and the ground will be attached to the H/U chassis. Once this is done, there are no CD's required in order to play your MP3, IPod, SatRadio, etc. When nothing is plugged into the jack, you have an open circuit just as normal. Once you plug into the jack, it closes the circuit and switches to your Aux. unit. The sound quality is very good and, because it is going directly into the board, has almost no signal loss.

exwrx: I've also attached the datasheet for the processor. You are correct that sharing can and is done on the board. Also the second diagram shows the use of a 5-pin (or 4-pin + seperate ground since I can't seem to find a 5-pin) connector which will allow for quick disconnect if you want or have to take out the H/U. As an added note, the 3rd diagram shows in picture form just where the wires go. It also shows that the caps that were removed from those points are being used again. Most have found that new caps are better than the ones that were removed though so keep that in mind.

If you or anyone else is interested or has any questions, feel free to let me know. I didn't come up with this mod and all credit goes to those who were brave enough (and smart enough) to fiddle around with the insides until they got it to work.