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Added aux jack to factory AM/FM radio on GEO/DELCO radio; Aux jack hack
Topic Started: Nov 27 2011, 03:33 AM (9,748 Views)
CookieMonster
New Member
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So I just joined the forum a few weeks back, my 97 Metro is still waiting on parts and sitting in a garage. After Thanksgiving I wanted to at least accomplish something so I turned my attention to the interior of the car. The interior is in good shape with the exception of the headliner and the faded dash but I really did not feel like dealing with either right now and turned my attention to the factory AM/FM only radio and speakers. The radio and speakers all sound great, speakers make plenty of bass and still have a good sound to them, the radio does not even have a scratch on it as the previous owners most likely were not the music type, they most likely listened to talk radio in the car.
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I have searched the forum and even online to see how other folks have added the inputs into their GM decks, and have come up with these common options:

1: They bought some original radio from e-bay that had an input added onto either a tape or cd radio or combo or one of the GM slave cd/tape units.

2: They purchased a crappy FM modulator for any where from $10 to $60, with a few rare exceptions most of them sounded horrible save for the hard wire to the antenna type.

3: They gave up and purchased an aftermarket radio, no real problem there but aftermarket radios look awful in any car. My biggest problem with aftermarket units is they do not dim with the gauge lighting and are usually too bright with dumb flashy screens and a remote you always can't seem to find 3 weeks after the radio is in. Plus the good ones are easily identifiable and seem to get stolen or damaged.

4: They jumped on you tube and watched the video or two of someone adding an aux jack using the GM tape player wiring, with mixed volume results, or had to stick a tape into the deck to get the sound to the speakers, most problem with the tape deck is adding a small pickup amp to feed the proper voltage to the amp board.

I was thinking of replacing the radio with a JVC double-din receiver, with a cd player and aux input so I could listen to my portable sat radio and other devices over the cars speakers. However I have had apart several factory gm radios over the years and even though I have never added a jack to any I was simply fed up with not using the deck to play music from my mp3 files or sat radio. I also own no cds or tapes as both formats are basically now considered dead, but portable sources one way or the other will never die and it is nice not to be tied to one format.

The answer for the question of how to add the aux jack has never really been revealed online, and those who do know never really tell it because they are either trying to make a profit, or have junked the factory radio and now couldn't care. Even most other GM car owners simply tell people to either buy a modulator or cassette adapter or buy a new radio, those options are all complete BS in my opinion, as well as a waste of money. There is a way to add the jack and install itself can actually be very simple or somewhat challenging depending on your elec/mech skills and where you want the jack to be installed, example: radio face versus trim piece next to the ashtray (the face of the radio is much more challenging, but well worth it in the end).

So here it is! Please forgive the not so HQ images as I used my cellphone camera to take these, and originally I was not intending on making any posting on this, and wanted the pics simply for reference.

Preview:
The GM ETR or electronically tuned radios, came out around 1982 and were used until at least until 2001 with the same old Delco AM/FM Stereo ETR board inside for all those years pulling in clear and trouble free broadcasts. The same boards were used in all of the Delco 1.5 din or GM size radios from the 80's and early 90's in all passenger vehicle lines, and later on right through to when the last years of the Metro and Cavalier/Sunfire got the double din radios. Why use one tuner board for so long? Simple, these boards were ea$y to produce and adaptable as the technology changed from analog to digital volume control. If you have any of these GM radios with maybe the exception of the Bose series this mod should work easily, I have never seen a Bose model apart, and while the same board is most likely in there as well, the Bose radios had outboard amps at each speaker, and most did not have balance controls identifying that internals were most likely very different.

Years of Metro & radios this will work with:


1995-1997 Geo Metro: Base AM/FM w/4 speakers, Cassette AM/FM, CD/Cassette AM/FM.

1997-2001 Chevy Metro: Base AM/FM only w/4 speakers, Cassette AM/FM, CD/Cassette AM/FM. (theses later radios had a new faceplate but it is still the same thing inside)

Mod will work on several other GM radios, PM me if you need some models this can be done to.

The earlier (89' to 94')Metro had a radio from Suzuki and I have never seen one apart, plus the smaller size of the radio means there will be more component integration on the individual PCBs or circuit boards. These cars do not have the GM/Delco radio, while this mod may be possible you would have to locate the signal processor chip and check sources like alldata to cross ref the chip and manufacturer for in/out locations.

The preferred radio truly is the base model AM/FM radio as it is much easier to work on and you can add the input to the face with a little work. I bet a lot of people have thrown the old base radio away......... oops.

Supplies you will need: (some variations depending on where you will mount your aux input jack and how you will mount it)

1: Headphone jack #274-0246 from radio shack, this jack allows for the switching of audio signals to/from a source when a 3.5 stereo jack is
inserted or withdrawn. It also has a screw on ring for mounting, it is however chrome. I bought this jack for under $3 with tax and the clear back panel worked for allowing light from the nighttime light bar to show thru illuminating the jack at night. The type of jack is switched stereo.
2: Basic small hand tools for removal of the stereo and opening of the case and internals, you will need a rather small philips for the back of case screws and other small screws inside the unit.
3: Soldering supplies, a small soldering pencil with stand and a roll of solder and the ability to solder wires and PCB components, you don't have to be a computer repair technician to complete this, but patience and a calm attitude helps if you are a beginner.
4: A household drill with bits varying in size from very small to about 1/2in, each individual style of radio may require different sizes depending on where you mount the jack.
5: 20-22 gauge multi-strand copper wire, using larger sizes makes for a more difficult install onto the jacks tiny posts, and if you are doing the faceplate install much harder to route through the slim panel gaps. The wiring I used was 16 or 18ga but I can't remember either way it is overkill and was not very easy to route. You can simply extend the length of the wiring if you are not planning on putting the jack on the faceplate and desire to mount it somewhere else like around the shifter or next to the radio on the dash panel itself, get creative there if you want to.
6: Electrical tape, good electrical tape, not the stuff that has been frozen and thawed in the garage over the course of 10 years, new quality tape is best.
7: A working Geo/GM/Chevy radio, your radio must be a factory radio, "DELCO" should be printed somewhere on the face or id tags on the back of the radio itself.
8: A source test unit (i-pod, cell phone with mp3 playback, port sat radio tuner, port cd player e.c.t.) and male to male 3.5mm stereo patch cable.
9:Correct wire cutters with the sizing hole strippers, not the ones used for home wiring or snipping bailing wire, these are too bulky and can slip easily.
10: Single razor blade, or good x-acto knife.
11: PATIENCE! Throwing tools and cussing will not help you at all with this mod, and if you do important small components may be lost or damaged, and details will be over looked most likely leading you to burn out the radio if it is incorrectly installed.

Lets go for it!

1:Remove radio from dash, this has been covered in this forum before so I will not be adding another how to remove your radio posting.
2:Open the radio casing, the side mount plates need to be removed to access (4 larger phillips screws, two on each mounting tab) the top and bottom cover plates, there are 2 screws on the back of the radios black painted rear section, one at top one a bottom leading to the lids.
3:Using a small flat screwdriver pry up the left and right sides of the top plate and slide it off of the radio unit, when you open the unit you should see this inside from top looking down if it is a base model, if it has the cd player you will need to remove the cd unit in order to get to the tuner.
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The top PCB in this radio is the GM ETR board, it is easily identifiable because the board itself is blue, and has the amber colored protective coating painted over the top, this board compared to the other boards has a much "older" style to the component mounting, this is the board you will be hijacking the source audio from.

4:Remove the 4 small silver screws that hold the PCB to the radio chassis, carefully pull the board up and out to reveal the wiring on the underside, do not pull the board out past where the wiring stretches and easily extends out as it may damage the small wires.
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This is the underside of the GM ETR board, it has several chips and other components soldered to it, you can really see the blue color here and compared to the board underneath which is the amplifier board, it has a much different style of manufacturing. The wires on the right go to the faceplate and the amp board where the antenna comes in and the main system ground, the brown ribbon style wire on the left is what we are looking for as it sends the left and right tuner signals to the amp board, be careful to not bend and components or change any factory settings on this board unless you do not want the radio to work at all.
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5:Using a razor blade or x-acto knife separate the areas between the last 3 wires there are 8 from left to right, you want the last 3 or #6,7,8, without cutting into the actual wire, think of them like webbing between frogs feet, cut the webbing only not the "bones" or wires.
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6:Cut wires 6,7 in half, about halfway up and carefully strip back the coating to reveal the bare wires do not cut wire 8 or any other wire at all, be careful when doing this, it should look like this. Remove the volume/pwr and fader/tone knobs by pulling them outwards gently, be careful as the fader and tone knobs have small metal tabs inside that need to go back or the knobs will fall off constantly!
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7:If you are planning on mounting the jack in the faceplate of a base 95-97 AM/FM radio, keep reading, if you are planning on mounting the jack in a cassette or cassette/cd keep reading but keep in mind the faceplate circuits and placing is different on a combined unit so these steps may not be exact for your model. If you are not placing the jack in the radio and are planning on mounting elsewhere or have another GM radio skip to step 14 for the connection of the wiring and grounds.

8:Remove the faceplate by gently lifting these black plastic tabs one at a time while pulling the plate gently forward until they are all released, there are eight tabs. Remove the shown ground wire to the faceplate, do not loose the small screw. The faceplate should be loose now, be careful and pull the plate forward gently, move the tuner PCB forward towards the faceplate to give more slack on the wires for easier access.
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9:Remove the faceplate main wiring by gently unplugging this small green clip on the amp board just under the pass through for the faceplate wiring.
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10:Remove the small silver phillips screws with a small screwdriver, that hold the faceplate PCB on, there are 5 if I remember correctly, the faceplate, PCB and light board will now be separated, be careful with these and set them aside.

11:I marked a center between the fader/tone knobs by measuring the distance from each hole to the other and finding the center, the other reason is I will have to modify the light board, PCB board, and radio case to get the wiring and jack to mount correctly.

12:Take your drill bits and find the same size as the jack mounting threads, I don't know what size was used, drill the faceplate out while it is separated from the light board and other components like the button set and PCB. Insert the headphone jack with the terminal side facing the fader knob for test fitting until it fits into the hole, it should be as tight as possible as the small set ring does not cover large holes.
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Note that this pic has wiring and light board in place, this was taken out of order but is a good representation of the mounting location.

13:When you are happy with the jack mounting, stop and move directly onto wiring the jack, as you will need to know how much room to make in the other panels.

14:Solder the wiring onto the jack, you will need 5 wires all about 9" long for this, I started with the ground. Be sure to mount the wires heading backwards for clearance purposes, do no use too much solder and make sure the terminals are not touching each other in any way or the switching circuits will not work. For those of you who are working with another GM radio, cut your wires long enough to reach from your mounting location to the inside of the radio, give an additional 5" at least as you can always remove some wire, but adding is impossible.
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15:Here is the numbers for what wire goes where, this is using the radio shack jack diagram and how you need to label the wires for install.
Jack position. Wire labeling description.
1:Ground Ground
2:Left + Left + to amp board
3:Left + to tuner Left + to tuner
4:Right + to tuner Right + to tuner
5:Right + Right + to amp board
For those of you adding to another GM radio besides the base am/fm skip to step 19.

16:It's time to modify the light board for pass through, the small injection molding circle between the knobs serves as a good point to drill through for the wires. Use extreme care when drilling this area, I used a 1/2 inch bit and made alterations to the hole using smaller bits to cut away extra material for the square corners of the jack.
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17:Now the really hard part, using the light board hole as a template and the lightbulbs as a position guide lay the light board onto the front of the faceplate PCB, trace the hole onto the board, you will have to drill out the board and re-route the circuits cut through with the drill, using wire and tracing the circuits by eye, sadly I have no good images of this, but I was not planning on doing a post on this. Here are some examples of the finished work.
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The three wires are traced to their pins on the main faceplate wiring and soldered in place to the components they were supposed to go to. again sorry there are no pics of this, but if you follow the circuits you have to drill through like a little map before hand they are simple to repair with wire and solder.

18:Once the faceplate PCB is repaired you can put the faceplate components together again, including the screws. There is enough room to bend the jack wires at a 90 degree angle upwards to the top of the faceplate, then run the wires through the hole the faceplate harness uses for the small green connector, gently push the faceplate back into position and secure the black mounting tabs. Reconnect the faceplate grounding wire with the small screw, you are now ready to add the wiring into the amp board and tuner.

19:The tuner to amp wiring is as follows, the wire on the right #7 is the right audio input, the wire on the left #6 is the left audio input. The wires are cut in half and here is why, the lower section of the wire goes to the amp, the upper section comes from the tuner, we need to stop the info coming from the tuner and substitute it with the audio from our external device. Do not attempt to skip cutting these wires in half and just adding a signal wire from the source it will overload the amp and destroy the radio. Solder the wires from the jack to the brown ribbon wires to the correct location, then wrap each connection in electrical tape, the reason I said good tape earlier is to prevent possible melting and leaking of the adhesive onto the amp board. This pic and diagram should help.
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The GM/ETR radio board in all years has these connections, if you connect the wires the same way as shown and wire the jack using the radio shack diagram this will be correct, please note: I cannot guarantee that all of the Delco ETR boards are exactly the same but they should be, there may be variances due to build date or what vehicle the radio originally came in but this is mostly the same board, check around a little to find out before you add the wiring in permanently.

20:Now solder your ground wire to the amp board main ground circuit. If you do not add the ground your mod will not work correctly, it will work but you will have to turn the radio all the way up and your source all the way up, you will most likely hear a tiny if any volume and will surely blow out the amplifier in the radio. just pass the ground wire through, strip back about 1/4in of the wire and solder it onto the main grounding circuit as shown. If you are doing this on another radio, look for where the antenna wires turns into regular wire, there should be another wire run next to it marked "ground" this wire connects to a circuit on any amp panel and connects all of the grounds to the main return line to the battery at the harness connector on the back of the radio. It is preferred to connect the ground to the amp board, and with solder. Reconnect the little green connector that feeds the faceplate.
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21:Reassemble the radio plates, make sure to get all of the screws back. Check that none of the wires are being pinched, and that non of your soldering work touches the case in any way, file down your solder or use elec tape to isolate the contact areas if any, by placing tape on the case panels where the solder hits. The silver screws on the ETR board that hold it in place also function as part of the noise suppression system and need to be in place. Reattach the covers and mounting tabs.

22:Place the radio back in the car but don't tighten down the mounting screws yet, plug the radio and antenna harness back into the rear of the radio, it is now time for a test run before hand completing the reinstall.

23:Turn your radio on and set the level to about 1/4 way up or enough to hear it clearly with the car off and in park, go ahead an plug in your source with the male to male adapter then insert it into the jack, the radio audio should cut right out! Now select a song or track to play, but turn your volume all the way down first, the radio does not have a leveling function that can deal with a possible sudden surge of volume. Play your track and turn up your device volume until it is a the same level as the radio volume, this may take a few times of unplugging the source and note that all playback devices are capable of slightly higher or lower volume outputs from the headphone jack. For example i have to turn my MP3 equipped cell phone headphone jack all the way up to hear it, on my i-pod it is only halfway.

24:If everything is working and sounds great finish putting the radio back into the dash! You can now cruise in style with minimal effort and cost, while keeping the factory radio and speakers!!! if you are luckily like me the cuts on the light board and clear back of the jack will actually allow a decent amount of light to shine into the input jack barrel when the headlamps are on, making it easy to find at night!
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Here is a shot of the light coming thru the aux input with the headlights on, not a good pic and it is much easier to see from the drivers seat.
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And here it is with the cable in and playing, although the picture does not have sound with it it is very clear, and sounds just like the radio, plus I can use my phones built in eq to fine tune the sound going to the radio!

Now all of this being said, if you live around my area I would be happy to do this mod to your factory radio, in fact this sunday i'm hitting my local scrapyard where there are 3 metros with the base radio, all of these are coming home with me and I will be doing this mod and re-selling them, for very modest prices as well as a few other GM staples.

Let me know what you think or if you have any questions, again sorry I just didn't have that many pics, and this post is a little long but this is the only write up that exists for this mod using the amp board directly, with a base radio. With a little poking around in your Delco you can do this as well!
-CookieMonster






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Woodie
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Fascinating and excellent! What wonderful information and presentation, thank you very much. Now, where were you ten years ago?
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wizard93
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Very good posting, CM! Hopefully I can find a factory Geo radio for my 94 Metro and mod it like you did yours.
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Scoobs
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Decal Vendor

damn that is awsome. now i wish i never gave away my factory radio :/ lol
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Coche Blanco
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Troll Certified

Awesome! Do they not make a kit that allows you to use the already-wired antenna spot?
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bogs
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Duct tape heals all wounds

CookieMonster, that is possibly one of the best picto-tutorials I have ever seen made. Very well written and pictured :thumb
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JellyBeanDriver
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:thumb
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todaugen


:rocker :cheers
Way cool.
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CookieMonster
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Coche Blanco
Nov 27 2011, 10:34 AM
Awesome! Do they not make a kit that allows you to use the already-wired antenna spot?
The only way to use the antenna hard wiring is with an FM modulator device, these turn your input from an audio device into a very short range FM broadcast. Mostly these do not work well and most owners get fed up and replace the radio, trying to actually plug the audio +/- wires from your device to the antenna jack would fry the tuner board in a few minutes as the tuner board is built to decode a broadcast signal, then deliver it to the amplifier.
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CookieMonster
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Woodie
Nov 27 2011, 05:30 AM
Fascinating and excellent! What wonderful information and presentation, thank you very much. Now, where were you ten years ago?
Hanging with the VW/Audi crowds :( , plus I used to think pioneer/alpine cd players were really cool, that was stupid as I have removed several decent, hard working, god fearing factory radios from various makes, sending them to their death, what a shame...
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Bad Bent
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Facetious Educated Donkey

Beautiful write-up! :thumb

I may have one of those lying around... :hmm
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cliffordpratt
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Awesome! I had a factory base radio from a '93 Saturn sitting around for a few years; I bet this would have worked on it. Pity, I threw it away earlier this year. Currently have a non-functioning aftermarket radio in my '92 Metro.
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Wr85
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I was wondering if anyone has done this mod to a 2000 Chevrolet Metro stereo with a tape deck. I followed most of cookiemonster's instructions but did not locate the brown ribbon style wires. The inside of my stereo is different. I was able to add the aux jack to the faceplate of the stereo. I just need to know which wires to cut and what to connect them to.

The following pictures are of my stereo and the inside boards. If someone can help me please chime in.

Thanks.

Face with aux jack
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Tape deck
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Back of faceplate
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Main Board
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bogs
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Duct tape heals all wounds

Do this mod to it? I don't think most of us even heard of it till he posted this :dunno
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Wr85
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Ha ha yeah i was really impressed with cookiemonster's original post. I read it a few times before i build up courage to do it.

Hopefully someone can help me out.
Edited by Wr85, May 26 2012, 02:34 PM.
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