Is it possible to make a "Sony CFS-201" cassette player/radio output sound from an external source?

Question

I have an old 1989 (bought new well into the 1990s) "Sony CFS-201" cassette player/radio with a broken cassette mechanism. I'm trying to use it as a "dumb speaker" by hooking up an audio cable from my Raspberry Pi to it, to play back a custom sound file on repeat to simulate white noise, but there is one "small" problem:

The only connector it has is for headphones, which means that it outputs audio instead of accepts audio input. There is a built-in mic, but no "mic connector" (it's just three small holes in the top of the device instead of a connector). I've looked closely everywhere in good lighting. Also, I read the manual.

Yes, I know that this is a cheap consumer electronics device from 30+ years ago, and half-broken on top of that. But it's also very sentimental to me, and it would've been nice to find a way for it to actually be useful again. However, I don't think this is possible.

And before you suggest it, I cannot just make it play radio static, because it sounds very unpleasant and not at all like "white noise". And I cannot repair the cassette mechanism to use a tape (plus that would get really annoying with having to rewind it all the time).

Answer 1

It may be possible to hack into the audio amplifier by feeding your signal into the "top" tag of the volume control as this is a common point between the pre-amplifier and the "power" amplifier.

^{simulate this circuit – Schematic created using CircuitLab}

Figure 1. Tapping into the volume control.

Figure 2. A cassette adapter. Source: Wikipedia.

Another - no-hack - option is to use a cassette tape adapter. These are basically a cassette with a play head mounted to face the play head in your player. Your plug the device into your modern player. You can make one and should be able to find plans on the web.