Reverse engineering/reprogramming a cheap novelty audio device

[Halcyon]

See attached.

I was given one of these novelty "buttons" where each press has a different sound effect/phrase, seems like chosen at random. These are just mass produced single-sided boards with various different themes, so I'd imagine there would be a way to reprogram the chip with different audio.

I've buzzed out the pins, which seem to be:

Unknown IC
Pin 1 - Battery positive
Pin 2 - Speaker
Pin 3 - D1 (Unpopulated)
Pin 4 - Switch
Pin 5 - Speaker
Pin 6 - Battery negative
Pin 7 - N/C (?)
Pin 8 - D2 (Unpopulated)

D1
Pin 1 - To IC Pin 3
Pin 2 - To Battery positive

D2
Pin 1 - To IC Pin 8
Pin 2 - To Battery positive

Any ideas where I can start? I do have an EPROM reader/writer, but not sure if the above pinout resembles anything standard?

[tom66]

I had always assumed these were based on OTP/eFuse ROMs and are not reprogrammable.  When we were looking at Nuvoton chips for audio the sales rep mentioned they have low cost audio options which omit the flash and are either mask ROM (for very high volume) or OTP (for mid-high volume). 

Example: https://www.nuvoton.com/products/smart-home-audio/audio-speech-controllers/powerspeech-series/n588hp340-otp/

[Halcyon]

I had always assumed these were based on OTP/eFuse ROMs and are not reprogrammable.

Ahh bugger!

[tszaboo]

I had always assumed these were based on OTP/eFuse ROMs and are not reprogrammable.

Ahh bugger!

I've even saw Jingle bells IC, which had 3 pins:
Power
GND
Jingle bells

[Halcyon]

Well there goes that idea. Maybe I can rip the guts out of this one and replace it with a programmable module.

[Gyro]

Replace the speaker with an LED (and maybe a series resistor) and you have a randomly flickering light. It's surprising how many random LEDs (tea lights) play pretty little oriental tunes when you shine them into a phototransistor. [Edit: a lot of the more modern ones produce some nasty white noise sounds].