Bendix/Ford 4TBT Car Radio - Solid State 1964

[paraph@se]

I'm looking for a schematic for this unit. A friend wants me to put and aux jack in one so he can use his iPod in a old Ford truck! Anyone have a copy or know where to look? Thanks!

[nickb]

How abut you tap in at the volume control?

[mozz]

May be in a sams photofact. Or the old trick where you just probe around, with your finger and find a spot where it hums loudly. Tap in to that.

[J M Fahey]

If itīs a 1964 radio itīs basically split in these blocks:
Antenna > RF gain > tuner/oscillator > IF amplifier > detector diode > VOLUME CONTROL > driver transistor > output transistor(s) > speaker

You do not need a schematic to find the volume control, itīs a plain potentiometer.
It has 3 legs: ground , wiper , "hot" , where it gets audio.
Identify it, itīs the one opposite to the grounded one, find the track which brings audio in and make a small cut a few mm from the solder lug.
Connect both sides of that track to a small 1/8" switching jack which you mount on any convenient place so when there is nothing plugged in, the internal leaf switch connects internal audio to volume Hot; when you plug your phone or MP3 player internal audio gets disconnected nd external goes to the pot.
Exact same wiring as in a Loop/Efx in jack.
You do not need a schematic for that.
Youīll need a special cable, stereo 1/8" phone at the MP3 player end, mono 1/8" at the radio end.
In theory you need to mix right and left earphone out into mono adding a 100 ohms resistor to each output, in practice everybody just joins them (I guess there is an internal resistor anyway) but if you want to play it safe, follow the rules.

This is a generic pocket AM radio; car ones were basically the same but with a couple extra gain stages , both RF and IF to pick distant stations when on a road in the middle of nowhere, but basic blocks remain the same.


You would need to split the track leading to R11, the volume pot.

Some car radios used a single ended Class A 2W germanium transistor power amp.
Wasteful in our view but not for them, since it was powered from the car battery.
A typical value is 5k Log/Audio.

[Enzo]

And if you still want it, there is probably a Sams Photofact file on it.

I used to always buy the service manual for any of my vehicles. Not the owners manual. It has all the parts laid out, as well as the vehicle electrical schematic. But I don't think they included the radios. But I learned how to do valve jobs and many other things from those books.

[joeverdi]

If itīs a 1964 radio itīs basically split in these blocks:
Antenna > RF gain > tuner/oscillator > IF amplifier > detector diode > VOLUME CONTROL > driver transistor > output transistor(s) > speaker

You do not need a schematic to find the volume control, itīs a plain potentiometer.
It has 3 legs: ground , wiper , "hot" , where it gets audio.
Identify it, itīs the one opposite to the grounded one, find the track which brings audio in and make a small cut a few mm from the solder lug.
Connect both sides of that track to a small 1/8" switching jack which you mount on any convenient place so when there is nothing plugged in, the internal leaf switch connects internal audio to volume Hot; when you plug your phone or MP3 player internal audio gets disconnected nd external goes to the pot.
Exact same wiring as in a Loop/Efx in jack.
You do not need a schematic for that.
Youīll need a special cable, stereo 1/8" phone at the MP3 player end, mono 1/8" at the radio end.
In theory you need to mix right and left earphone out into mono adding a 100 ohms resistor to each output, in practice everybody just joins them (I guess there is an internal resistor anyway) but if you want to play it safe, follow the rules.

This is a generic pocket AM radio; car ones were basically the same but with a couple extra gain stages , both RF and IF to pick distant stations when on a road in the middle of nowhere, but basic blocks remain the same.


You would need to split the track leading to R11, the volume pot.

Some car radios used a single ended Class A 2W germanium transistor power amp.
Wasteful in our view but not for them, since it was powered from the car battery.
A typical value is 5k Log/Audio.

Hi J M Fahey
It seems you know quite a bit about this process. I would love to consult you on a project I'm doing for my 1964 Bendix Radio from a 1964 Ford Falcon. I don't know how to read schematics (though I've watched a couple tutorials and am starting to learn), but not quite sure what steps to take. I'm new to this platform, so I'm not sure if you can send me a direct message or contact me somehow. I can't seem to figure out how to contact you directly. Please let me know if you're able to provide assistance. Thank you!