Delco AM/FM/CB/Cassette radio 3.5MM input addition

[dyeager535]

Hello!

Hoping someone on here can help me. I saw another post about a Delco radio, so I'm optimistic!

This radio is an early 80's model, which has the LCD display as opposed to the "older" style with manual tuning.

Since this is what fits in the vehicle, it's what I intend to stick with. Up to this point I've been using a cassette adapter to plug my phone into, which allows me to be "hands free", or play MP3's from it. Of course, the cassette deck appears to have now failed.

I have had the idea to add a 3.5MM input jack to the radio for some time, but had little incentive to do so until now. My two concerns are that I have no idea where the jack would be connected so as to "simulate" a tape being played, and how to trigger the radio to switch to the auxillary input the same way it does when a tape is inserted. Those are the two I really need help with. I would guess the switching portion is electro-mechanical since the cassette physically moves the tray, which switches it from the radio to cassette playback, but I know anything can be modified or changed with enough time and ingenuity.

Obviously the radio is going to have to be at least partially disassembled, and some soldering will have to be done, and I have no problem with that. It's pretty obvious from the LCD on mine, and other comments I've seen, that the soldering on these tends to be pretty poor from the factory, so I can kill two birds with one stone so to speak, when I open it up.

Thanks for any help!

[selldoor]

Re: Delco AM/FM/CB/Cassette radio 3.5MM input addition

Whilst it does not answer your question these take no skill ingenuity or effort and very little cash?
http://www.ebay.co.uk/itm/Car-MP3-pl...item232604869b


Here is a one from china less than USD3

http://www.ebay.co.uk/itm/Wireless-F...item20c65870af

[dyeager535]

Re: Delco AM/FM/CB/Cassette radio 3.5MM input addition

I had one similar, pretty cool, but I'm trying to get away from extra gadgets if I can! I really like being able to use the phone for an MP3 player, it eliminates one more thing I have to keep track of and swap between vehicles, and no having to worry about switching something off, or changing volume, etc., when a call comes in.

[randtek]

Re: Delco AM/FM/CB/Cassette radio 3.5MM input addition

Unless you have complete schematics on the unit, it is going to be difficult to make this work. The cassette player will have sensors to detect if the tape is inserted, and reels are rotating. you will probably need to fool those in order to use the cassette circuitry as an auxiliary input.

[SuperDuty]

Re: Delco AM/FM/CB/Cassette radio 3.5MM input addition

I did that to my 1984 Delco unit. It's pretty simple actually, just locate the harness of the cassette player, find the wires for the left and right signal, and the wires for the radio and cassette signal, and the 12v. All you need is some wires, and jack input and a six poles DPDT switch.

Here's a simple schematic I made, it needs an update but if you have the unit in front of you, it should be easy to understand :

[dyeager535]

Re: Delco AM/FM/CB/Cassette radio 3.5MM input addition

Don't have it in front of me, but thanks for that! Been looking at the manuals available on ebay, too rich for my blood. From your diagram it is as simple as I was hoping it was wiring-wise.

Is it feasible with a little more effort to make the radio automatically switch when the input is plugged in? I understand what needs to happen to make it switch, and the 3.5MM plug doesn't appear to provide a means to accomplish that. Switch isn't terrible, I'd prefer to make it automatic if possible though.

[lti]

Re: Delco AM/FM/CB/Cassette radio 3.5MM input addition

You can get those jacks with switches built into them.

[Th3_uN1Qu3]

Re: Delco AM/FM/CB/Cassette radio 3.5MM input addition

You can get those jacks with switches built into them.

Most of them are just like that actually, and they go for peanuts. I just patched an aux input into a Panasonic stereo yesterday. Tapped into the CD player signal.

The only snag i ran into was that the IC amp had a muting pin, which was activated when the CD was on pause or stop. I just disabled the muting (grounded the pin) and everything worked fine. Your radio is old enough to not have this, so don't worry.

[SuperDuty]

Re: Delco AM/FM/CB/Cassette radio 3.5MM input addition

You can get those jacks with switches built into them.

Yeah I thought about it but I only had some scavenged parts on hand :P

[dyeager535]

Re: Delco AM/FM/CB/Cassette radio 3.5MM input addition

You can get those jacks with switches built into them.

Can any of you link to one of these? I find the jacks, but not ones that mention switching. How many pins do they have then? 7?

Edit: Ok, I've found 8, 9 and 11 pin variants, but no pinout for them. Looks like the "front" five pins are the speakers/ground, and the back would be the switching portion, having the pinout for those would be handy!

[Th3_uN1Qu3]

Re: Delco AM/FM/CB/Cassette radio 3.5MM input addition

All jacks i've used so far have 5 pins... Ground is shared, the two (left and right) signals are switched.

[dyeager535]

Re: Delco AM/FM/CB/Cassette radio 3.5MM input addition

Might have to humor me a bit.

Based on the wiring diagram shown above, with a 5 pin jack, how would you switch the radio and cassette wires, along with providing the 12V? I thought that was the "shortcoming" of the 5 pin jack when wanting to automatically switch cassette(or aux input in this case) to radio?

[Th3_uN1Qu3]

Re: Delco AM/FM/CB/Cassette radio 3.5MM input addition

You could tap into the radio tuner signal not the cassette. Turn the radio on, plug the jack in, you have MP3. Unplug the jack, you have radio.

[dyeager535]

Re: Delco AM/FM/CB/Cassette radio 3.5MM input addition

Captain Obvious just hit me. Thanks! Much simpler, duh!