Digital Full Band Modulator Model: M69

Introduction

Although I own the M69 for a while, I haven’t used it much – but on the few occasions I did sound never worked. The image was clear but the sound was just white noise hiss – and I had to turn the TVs all the way down.

Solution

I had more time to understand what is going on – and decided to have a look at the little manual it came with:

After figuring out how the device works with the CH1/CH2 buttons, it turns out that mine arrived with a non-standard configuration for the ‘Audio System’ / ‘Function Bit’, it was set to value ‘3’ (appeared as 0.3 on the screen), while, for the PAL TV I was testing against, the correct value that gets the sound to work is ‘1’ (appears as 0.1).

This made the sound work perfectly 🙂

A photo with it connected to the Raspberry Pi 3B+

I decided to make a small comparison, I have a small old Black and White TV that also accepts RCA Composite Video input, so I decided to take two photos, one (left) with the Composite Video from Raspberry PI going directly to the TV, version (right) where the Compite Video passes through the Digital Full Band Modulator Model M69 and then it goes to the same TV’s Antenna input:

Needless to say, it does work – excellent for nostalgia!