'86 stereo - MP3 in?

[baccaruda]

Hey, electrical guys.

I was wondering about the possibility of modding the stereo so that instead of plugging a stock tape deck into the back, one could somehow plug in an MP3 player (who uses tapes anymore anyway?)

Yeah, I could get a modern head unit but I like that the stock radio doesn't stick out. I have a tape deck and adapter, and I don't want to get an FM thingy. I want to eliminate the tape deck and just plug into the mp3 player, maybe with a small project box hidden in the dash if I need to add a small amount of circuitry to the adapter. I'm hoping someone here knows enough about the way these radios are powered to know if this is feasible.

 

I took apart a working tape deck and a dead radio to get these pics: The jack is on the back of the radio, and the tape deck cord has 5 wires that solder onto the board as pictured. I'm wondering what it would take to splice something onto the tape deck cord, because disassembling and reassembling the radio to change the jack would be a huge pain.

 

 

 

I overlaid the paths on the back of the circuit board onto the front with the components.

The white wire is powered, as it comes from the fuse. The black wire is for the left channel and the yellow wire is for the right.. I'm concerned about what the other 3 wires are for.

Edited March 8, 2010 by baccaruda

[GLCraig]

If you can find a working tape deck, one of these works just fine.

 

http://www.amazon.com/Belkin-F8V366-Mobile-Cassette-Adapter/dp/B0001V2MF4

[crazyman03]

Well, there /is/ a couple easy ways and a hard way to do this. 1 easy way would be to get said tape adapter for a working deck and run it that way. I've done it.. and it works quite well, even if the motor doesn't spin inside the tape deck. OR you can get a FM Transmitter and run that.

 

As far as FM Transmitters go.. they make simple plug and play ones, and they make complex ones. Both work well, its just a matter of how much you like your deck ;-). The complex ones actually go in-line with the antenna connector that plugs into the back of the radio, tune to the specified station and No interference. When you turn the deck on, the Transmitter turns on and just plug your MP3 player into its Audio Input. The plug and play ones you can get as a Walmart special. You simply put batteries into it, plug into your MP3 player and tune the radio. (if you really wanted, and i've done this too, you can hard-wire the plug and play one too with the proper voltage adapters)

 

As far as interfacing the mp3 to the plug that works for the tape deck.. I've never tried that. If you have some time on your hands, a DMM, and a bit of an imagination.. You probably could get it to work. all you really need to find from the plug is -,+ Left and -,+ right audio channels. it might have a common ground for them so be sure to check for that. This also is assuming that the factory deck receives the audio that way, I'm sure it does.

 

 

 

-Justin

[Subarutex]

Some trial and error, you should be able to figure out what 2 locations on the plug are the signal wires.

 

Once you know that, you just splice in there!

[baccaruda]

Tex, the black wire is for the left channel and the yellow wire is for the right.

You think I can just wire those two up to an A/V headphone jack?

 

Everyone, I revised my first post for more clarity. Thanks for your opinions so far! I don't really care about the radio, but I don't want to fry my cell phone or dedicated mp3 player...

[Subarutex]

Yeah, I would try to just hook it up. Should work!

[baccaruda]

OK, I'll get an extra headphone jack to cut up this week.

[baccaruda]

Allright, I tried twisting the wires (L, R, constant) together (separatly-together ) coupled to a headphone jack, with no results.

 

It occurred to me that when you pop in a tape, the radio knows when to shut up and accept the auxiliary input... so I tore the rest of the tape player apart. The white (fused) wire goes to another board, though some sort of switch, and comes back to power the red wire. So I think the radio passes current thru the wires to the tape player and back, to enable the trigger of the auxiliary in/out. The blue wire runs to all of the capacitors on the board I pictured above, so I don't know how that serves the auxiliary circuit...

 

I don't suppose anyone has a wiring diagram of the radio & tape player internals? My FSM set doesn't...

Edited March 9, 2010 by baccaruda

[eulogious]

I believe that there is some sort of amplifier in there and you have to find the inputs to that, like from the tape player. I bet that's why it didn't work just wiring it up to the speakers... Once you find those inputs to the internal amp, then it's just figuring out which input is left and which is right. The problem is finding those inputs. Trial and error with a DMM is really your best option.

 

I would tend to lean that this is going to be a little difficult to achieve, since you don't have a wiring diagram for it. I wish I could help you out more, but that's all I got. Good luck, it will be interesting to see what you come up with!

[xbeerd]

On my kenwood deck (with changer controls) i used to have, if you put a 10k resistor between the 2 non audio pins in the connector that went to the cd changer it would realize the cd changer was present.

 

it would seem to me that if you found which wires were the L/R/GND you could try putting a resistor between the other 2 pins, of course, at your own risk as there could be a possibility of shorting out (maybe??)

 

 

I have found that with these radios and their crappy antennas that the FM transmitters work pretty good. I have one of these. its a Harmon Kardon Drive+Play. has aux out and fm transmitter which you can program any station. with the antenna all the way retracted the unit can overpower REAL radio stations in my area.

 

here is how i put it in. You can find these things for like $20 at Goodwill sometimes.

who needs a clock?

[xbeerd]

maybe this will help a bit?

 

http://www.instructables.com/id/Add-an-auxiliary-MP3Ipod-input-to-your-cars-st/

 

 

i think i have a stock radio with a tape deck at home in the garage, if i remember tonight i'll dig around and see if i can come up with anything to help ya out.

[robm]

You do NOT want to tie your MP3 player to the amp inputs on the tape deck board. They are designed to take a very tiny signal off the tape head and crank it up to 1 volt or so. Your MP3 is already putting out enough signal to use as an input to the power amp in the radio.

 

I think you are on the right track with the switching signal, something has to turn the amplifier in the radio on when the tape goes into the slot.

 

Good luck.

 

OH: And I haven't found my radio to be crappy at all. It is the best radio I have ever had, in fact. I live in a pretty mountainous area, with few transmitters, and the stock radio in my Loyale has the fewest holes in reception of any I have owned.

[xbeerd]

 

OH: And I haven't found my radio to be crappy at all. It is the best radio I have ever had, in fact. I live in a pretty mountainous area, with few transmitters, and the stock radio in my Loyale has the fewest holes in reception of any I have owned.

 

I really shouldnt say crappy, the reception with the antenna out is just fine, i just dont like antennas so i keep it tucked in, which helps my fm transmitter situation.

 

 

I really wish i was at home at the moment so i could look at/for my other radio,

thinking out loud....

so this radio connector has 5 pin, 3 of them are for the audio L/R/GND. If you figure the pinout, which it seems we have figured out the audio portion, i wonder if its as simple as just a on/off switch on the other 2 pins to make it work.

[robm]

We are both right. My problem is not enough transmitters, your problem is too many!

 

A 1/8" stereo jack for the MP3 player, with a switch beside it to switch in the radio when required, would be a nice and simple way to deal with it. A 3 pole switch (L, R and signal to the amp) would be perfect, but not the easiest to find. If a resistor is required, no problem. It could all fit on a plate mounted where the deck is supposed to go.

[xbeerd]

for reference.. kinda.. i made an adapter for my kenwood from this diagram...

 

I am going to try to poke around tonight and see if the same 10k resistor(or any resistor for the matter) will work, all the resistor was doing was letting the deck know something was there to let it switch over.

Edited March 10, 2010 by xbeerd
busted for hotlinking... HAHAH nice image!

[idosubaru]

Try what you already tried but put a tape in the tape player. Maybe a blank one or one with no tape, just so it "thinks" or triggers it into "tape mode". This might help testing as well. Test voltages/signals with tape in and with tape out to find your money maker.

 

The FM transmitters that plug in (NOT the wireless ones that are so common) are much better. The wireless ones are just easy, but obviously you can get your hands dirty. You just give it switched power and that's it, it plugs into the antenna wires. They are much better than the wireless kind.

[xbeerd]

Try what you already tried but put a tape in the tape player. Maybe a blank one or one with no tape, just so it "thinks" or triggers it into "tape mode". This might help testing as well. Test voltages/signals with tape in and with tape out to find your money maker.

 

The FM transmitters that plug in (NOT the wireless ones that are so common) are much better. The wireless ones are just easy, but obviously you can get your hands dirty. You just give it switched power and that's it, it plugs into the antenna wires. They are much better than the wireless kind.

 

ive read about doing that with cd changer/hacks. my guess is that it'll work BUT i think he was wanting to rid himself of the tape player all together.

[Subarutex]

I would bet inside the tape deck is a simple switch, a manual one that probally completes a circuit when closed.

 

Figure out which 2 wires lead to that, and connect them. One wire is probably ground, and the other is the "on" signal. The third unused wire will be the power wire for the deck. I would guess that the simple switch just puts the "on" signal to ground.

[xbeerd]

I would bet inside the tape deck is a simple switch, a manual one that probally completes a circuit when closed.

 

Figure out which 2 wires lead to that, and connect them. One wire is probably ground, and the other is the "on" signal. The third unused wire will be the power wire for the deck. I would guess that the simple switch just puts the "on" signal to ground.

 

wouldnt the last wire need to be a GND or "-" for the audio? or do you think the GND to be shared all around in this case?

 

edit: *nevermind

Edited March 10, 2010 by xbeerd

[baccaruda]

The tape player.. uh, doesn't exist anymore. Not in one piece anyway

 

Thanks to all for your help brainstorming. I do want to rid my car of the tape player, plus the adapter is cumbersome and involves wires all over the car, and sounds like crap anyway.

 

There are a couple of small switches in a couple spots on the tape player circuit boards. I'll see how clearly I can trace them soon.

 

Of the 5 pins, I know that:

Black - left

Yellow - right

Blue - (capacitors)

White - fused 3v

Red - incorporated with white 3v circuit somehow

 

Also, these wires are sheathed in fine copper wire mesh which is gathered and soldered to a bracket that screws to the metal tape deck body, presumably to ground the shielding or something.

[xbeerd]

#&^%$&&QW&V &@%@$!!!!

 

the radio i thought i had.. well.. i dont have it anymore. Grrr!

[xbeerd]

i forgot to ask, how did you come to the conclusion that the black and yellow were the L/R + wires?

DUH, i just zoomed in on the original picture, found the Lch/Rch labels. Doh!! haha.

 

could you maybe post a picture of the plug end of the cable and diagram which wire corresponds to each pin on the plug?

maybe that'll help. i've been searching around the net on some MP3car forums etc.

 

Of the 5 pins, I know that:

Black - left

Yellow - right

Blue - (capacitors)

White - fused 3v

Red - incorporated with white 3v circuit somehow

 

i guess if i were doin this right now, i'd try wiring the grounded sheath to the ground on the headphone plug (opposite end of the tip, i assume you know that but just to be sure), the yellow to the center, and the black to the tip. if you can do that and leave the white/red as they are, maybe try shorting that switch on the lower part of the board it might switch over.

 

if that dont work, maybe the blue is the ground for the audio? i cant see the markings on the caps but i think the blue is on the - side.

Edited March 10, 2010 by xbeerd

[baccaruda]

K, here's some pictures of the caps and a diagram of the plug.

The caps' dark blue stripe does not seem to connect to any of the blue wire's territory, as far as I can tell. Also, the red wire (3v of some kind) goes to the big cap in the upper right area of the board as pictured earlier - non-stripe side.

 

 

 

[baccaruda]

Here's another version of the circuit boards; I color-coded the immediate paths each wire takes and overlaid them.

Here it is larger if anyone wants: http://img121.imageshack.us/img121/667/radioguts2big.jpg

 

 

Also, the red wire that can be seen right under the fuse goes to another smaller circuit board, and it powers a switch that switches between a dead end and other components... which (among other things) goes through a resistor, and then returns to the boards pictured via the purple wire in the middle (it says "7" and is right next to the red wire).

 

Thanks to you guys for your help so far. I'll take pics of the other boards from the tape player and from the radio soon.

Edited March 10, 2010 by baccaruda

[ihscout54]

I did something similar on my car. On the EA81's the deck and head are separate units joined by 2 DIN cables (one male one female) coming out the back of the units. I used the cable from the tape deck and soldered a 3.5mm jack on to the end. I never solved the switching between tape over-ride and radio. I just plug in the I-pod and turn the dial till theres no station and little noise. Usually all the way to the 108+ side on FM. Works great, though sometimes I will get some noise, but its faint. The only thing I wish Ide have done was to set it up w/ charger and ipod plug. I dont recall which wires were what, but I belive it was standard DIN.