Another radio question- cassette input

[YY1]

Do all the am/fm stereo circuit boards have a mounting pad for the cassette input?

If so, it should be relatively easy to add a 1/8" jack for aux, right?

How did they select the cassette as the input?

 

[krowbar]

Huh?

 

[Bruzilla]

I would guess a voltage yes/no setup.

 

[kellycom]

if the cassette player in the radio works then just get this: http://www.walmart.com/ip/RCA-Cassette-Adapter/16553075
8 bucks and you can now plug anything with a 3.5mm jack.

 

[poly3521]

http://www.ebay.com/itm/71-72-73-74...Parts_Accessories&hash=item5b01251652&vxp=mtr
Here it is, but I have no idea how they did it. Never been inside of one. Good luck.

 

[Bruzilla]

So if there's a pigtail connection and no switch on the front, I'm guessing the circuits on the board are designed to detect a voltage at the pigtail connections and switch from radio to cassette mode.

 

[72RoadrunnerGTX]

The switching took place in the cassette deck on the pig tailed radio/cassette set-up and was mechanical, predates any kind of voltage sensing. Using the pig tailed radio without the cassette player/recorder required a bridging plug inserted into the pigtail or the radio wouldn’t work at all. The pig tail contains line-in for the radio amp and line-out for the radio tuner section, could be easily adapted for an aux line-in. would need to switch it manually however.

 

[Bruzilla]

So... how did the unit know to process radio signals vice cassette signals if there was no sensing and no switch? Going by your description the unit would play cassette signals when the connector was plugged in and nothing when it wasn't, which doesn't make sense. :eusa_think:

 

[ODZKing]

I purchased one of the newer ones with upgraded electronics and when you plug in the MP3 player it senses the voltage or audio or something and bypasses the radio direct to the amp.
It does work.

 

[Bruzilla]

I thought YY was asking about vintage units, not modern ones, specifically if they all used the same circuit boards and you could soldier a connection onto the non-cassette capable one and play cassette, MP3, etc, through the old box.

 

[kellycom]

after re-reading his post. i think that is what he asking. But as ODZ points out you can get the radio converted to modern internals. I just did that for my 66 Charger. It's not cheap, but helps to keep the originality of the old radio. My reply was off base since i thought it was a cassestte equipped radio.

guess we'll wait for YY1 to reply.

 

[72RoadrunnerGTX]

So... how did the unit know to process radio signals vice cassette signals if there was no sensing and no switch? Going by your description the unit would play cassette signals when the connector was plugged in and nothing when it wasn't, which doesn't make sense. :eusa_think:

These original radios predated any kind of IC based audio switching or signal sensing. Line level audio was routed to the cassette deck via the DIN connector to a normally closed mechanical switch in the cassette deck, routed back through the DIN cable to the pre-amp in the head unit. When a cassette was inserted for playback, line level tape signal was switched to the head unit pre-amp. DIN connector radios were shipped with a bridging plug in place to allow radio operation without a cassette deck connected for this reason. A disconnected or disabled cassette player/recorder will cause no audio at all from radio without a bridging plug in place.
It’s been a while since I’ve compared the DIN AM/FM stereo radio internally with the non-DIN AM/FM stereo version, I recall however the boards were the same and wiring for the DIN cable was the only difference.
Could put together a DIN cable with DPDT switch, and 1/8” phone jack pretty cheaply with Radio Shack parts to input an AUX line level audio source.

 

[YY1]

Yep, that was the question.

Now, to find the mount points on the PCB.....

 

[72RoadrunnerGTX]

couple of more pics, for you. The PCB connection is pictured for radio section line level out. On a non DIN AM/FM stereo radio, this would be wired to directly to the volume control.
On a DIN version, routed out through the DIN, then back through the DIN to the volume control as pictured.

 

[SureGrip]

View attachment 485822
View attachment 485823
couple of more pics, for you. The PCB connection is pictured for radio section line level out. On a non DIN AM/FM stereo radio, this would be wired to directly to the volume control.
On a DIN version, routed out through the DIN, then back through the DIN to the volume control as pictured.

So, if you connected a 1/8" jack to those two pins, you could use that as an audio input?

 

[72RoadrunnerGTX]

Well here’s an old thread revived. Yes, old school line level.

 

[ODZKing]

Since I posted my response in 2014, I have since gotten rid of the repro radio. I didn't like the way it worked at all and IMHO did not sound good (to me). All bass or all high end, no compromise.
You cant dial a frequency, it always scans so if you have a station that is weak it skips it. To adjust the front vs rear volume, I had to tune all the way to the right, wait 2 or 3 seconds and the left-right control would become front-rear. I regularly turn the battery off by way of a disconnect on the battery ground which no doubt everyone has seen. And it always resets the radio which required a reprogram each time. I finally got fed up, sold it for less than half what I paid for it and refurbished my original AM/FM Stereo factory radio and reinstalled it. Sounds WAY better and works fine. I now simply use an FM transmitter/MP3 player to play music.
https://www.ebay.com/itm/LCD-Wirele...688523?hash=item33c4d5f5cb:g:1d0AAOSwOtdYUS9V
There are hundreds out there and as you can see they cost next to nothing.
Good riddance the the repro radio.