MP3 Player (PJB100 - 20GB)

http://www.mp3factorydirect.com

 

GM/Delco CD Changer 9-pin Y-Harness

http://unitedradio.com/auto_main.shtml

United Radio Phone: 1-800-448-0944

http://radiosandmore.com

 

Peripheral Electronics GMKENX protocol converter

http://www.peripheralelectronics.com/periph_products/new_products.htm

http://www.peripheralelectronics.com

The basic problem is this: How to attach a portable MP3 player to the OEM stereo system in a way that looks integrated, has high quality sound, and has the ability to remain charged. This is not just any portable MP3 player; this is a PJB100 20GB portable player, containing over 12 days of high bit rate quality music. This unit has excellent sound quality, a very large storage capacity, and a very user simple interface. This unit is perfect for in dash mounting…if only there was a way to integrate it into the system.

This has been by far the most troublesome modification to date, a perfect example of the 90/10 rule: The last 10 percent takes 90 percent of the time. After hours of research on the web, the chosen solution looked to be the best solution to date. Granted the use of a tape player adapter or FM-modulator would work, but the sound quality is poor compared to a direct connection. Having the player lying about in the cab was also not part of the design goal. An in dash, integrated, solution was needed.

The resolution to this problem started by discovering a 9-pin GM/Delco CD Changer Y-harness. United Radio built this part for the explicit purpose of adding a CD changer to the stock GM radio by tapping into the external tape deck wiring harness. Since the GM stereo head unit talks to the external components via a daisy chained serial link, this Y-harness proved to be the way to add a CD changer.

The Y-harness can be obtained from United Radio or Radios And More (same company) and asking to talk to somebody in the automotive division to purchase the GM/Delco 9-pin CD Changer Y-harness adapter. Peripheral Electronics may also sell this adapter, as it is needed to use the GMKENX converter. There is some discussion about which radios are compatible with this harness, and if OnStar works or not.

Most of this information is wives tales about who heard what form which web site. With the 15765357 labeled head unit, the harness works with an external device adhering to the GM/Delco stereo communication protocol. The head unit in fact supports three external devices: OnStar, tape deck, and CD changer. The internal CD player and AM/FM radio also continue to function correctly.

Now that the technology to add a CD changer is in place, on with the job of finding a CD changer that supports RCA AUX stereo audio input for the MP3 player. Since the GM branded changer does not support AUX audio input, a third party device is needed. Due to the use of a third party device, a GM protocol converter is needed. Only one protocol converter was eventually found that could do the trick. It turns out that Peripheral Electronics makes a device called the GMKENX, which is a GM/Kenwood CD changer protocol converter with an RCA AUX stereo input for things like MP3 players and VCRs. The major problems have now been solved (90 percent done). One slight inconvenience was that a CD changer is required to be active in the system, so the least expensive compatible changer was used: The Kenwood KDC-665 6 disk changer.

The GMKENX device allows a Kenwood CD changer to run with a factory GM head unit (via the Y-harness adapter), and also has the ability to switch to AUX audio input with the flip of a switch. With everything attached, all works as expected…sort of. The following is a detailed first glimpse of the stereo behavior after the protocol converter, CD changer, and MP3 player were attached to the system.

The Test Setup:

--Attached the cassette and CD changer protocol converter to the Y-harness.

--Attached the MP3 player to the protocol converter unit.

--Placed 6 CDs into the Kenwood KDC-665 changer, one CD in the head unit, one cassette into the cassette player (where else), and hit play on the MP3 player.

 

The Test Results:

--The AM/FM button worked correctly: FM1/2/3/AM cycled as Delco intended

--The CD/AUX button cycled through the internal CD, the tape player, and the CD changer. Grounding the GMKENX AUX input wire (this is the AUX audio enable switch) let the MP3 audio through to the system when the changer was selected (no change of icon in the head unit, it remained the CD changer icon as intended).

--Hitting the OnStar button took over and stopped all units correctly…

 

…sort of…

 

There is a bug in the GMKENX protocol converter (actually several). The changer correctly stops and does the right thing when it is playing. However, when AUX audio input is let into the system, it continues to play even when OnStar is activated. When you switch between other inputs (tape/CD/AM/FM) the protocol unit kills the external audio. It just does not do so when the changer and external audio are selected and OnStar is activated. No great loss. The OnStar people like music too, right?

 

Head unit number key behavior regarding external changer:

1 (REV) Changes track to previous track

2 (RDM) Plays random disk/track

3 (NEXT) Goes to next track

4 (REV) Plays the current track fast in reverse

5 Selects next disk in forward round robin fashion

6 (FWD) Plays the current track fast forward

 

Other problems found since the initial behavioral tests: Occasional communications problems where the protocol converter is not fully recognized, requiring a full power cycle of the system, the rare CD changer/scanning problems where certain tracks or disks do not show up, as well as the excessive power consumption problems (remember the 400ma battery drain talked about in the AUX battery section?). There is also a problem with ignition noise since the GM head unit does not deal well with noisy signals, but what do you expect from an OEM radio.

 

The various bugs in the protocol converter CD interface are minor since it is used mostly to play music from the MP3 player, so problems like an occasional missing track are not an issue. The biggest two problems to deal with are the excessive power drain and the ignition noise. To solve the ignition noise problem, a basic audio noise filter was tapped into the power leads going to the protocol converter at the Y-harness. After this change, the ignition noise is barely audible at full volume with no audio input.

 

Moving the protocol unit power supply to the AUX battery solved the power consumption problem. Grounding the protocol converter metal housing to the AUX battery ground also helped reduce the ignition noise a tad bit more as well. Since the AUX power has a breaker switch, power can be removed when the vehicle is not used for a few days.

Now that there is good, clean, MP3 music being played through the factory stereo system, the CD changer has been installed and the PJB100 needs to be integrated into the center console. The CD changer lives under the passenger side second row seat, with the control/power cable running under the carpet to the center console. The location chosen for thePJB100 MP3 player is the covered tape/CD tray in the lower portion of the front center console. After some creative grinding, cutting, and faceplate creation (Tap Plastics is your friend), the MP3 player had a home.

The PJB100 fits nicely in this location, and is easily removable for those times when a long vacation away from the Suburban is called for. In addition to providing audio from this location, the PJB 110v wall power charger supply line is run from the PBJ100 player, down through the center console, and into a 300 watt inverter to charge the device when it needs it. All wires remain hidden, and the unit is entirely integrated into the center console. The PJB100 runs from its 10 hour battery most of the time due to the unsolved problem of charging noise leaking into the audio system. The 110V charger is much quieter than the 12v charger, and was used for this installation. The upside is the added bonus of getting a 300 watt power inverter for odd jobs.

POWER CONSUMPTION UPDATE:

After contact with the Peripheral Electronics' engineering department, the following new information has come to light regarding GMKENX power consumption:

 

------------------------------------------------------------------------------

Date: 2001.05.30 10:32 AM

From: Mark F. Dames, mark.pei@fastwave.net

 

Sir,

 

I have some info for you that may help. Please open one of the

GMKENs and see if R4 has been clipped on one end to remove

it from the circuit. R4 is a 47K resistor located near the plug for

the cable that connects to your OE stereo. If this resistor is not

clipped, then do so.

 

Please e-mail me if you need any additional info.

 

Mark

------------------------------------------------------------------------------

 

The following are the results of some power consumption tests after making the above mentioned modification to the GMKENX:

Amperage/Condition:

410ma

CD playing

 

176ma

RCA input selected on GMKENX

 

176ma

Radio selected on head unit

 

167ma

Turn ignition off while either

CD or radio playing

 

14ma

Turn stereo off with either

CD or stereo playing

 

5ma

Turn stereo off then turn

ignition off with either CD

or radio playing

 

With this factory recommended modification, the general power consumption will be around 170ma, which is better than the previous 400ma. Power consumption of 14ma could be obtained, but nobody will remember to turn the head unit off before turning the ignition off. This power draw is acceptable as the unit is now attached to the AUX battery and can be disabled via a breaker switch.

 

From the installation notes that came with the GMKENX unit:

Compatible Radios: The GMKENX has tested compatible with the following radio codes:

09354175

16265855

15757508

161631131

15764358

09366404

09383075

16213352

09354155

09368025

09375895

16213825

 

Due to the extensive number of radios available by GM may be additional radios that are compatible but not on this list. If you discover a radio that is compatible but not on this list, please contact Peripheral at the numbers below.

 

Tech Support: 727-572-9255 ext. 230 or 858-695-2133

email:SubRider

10/16/01