Lab Gruppen FP6400
I have worked for many years with the VME team in Knutsford. Last time I popped in there were 4 Lab Gruppen
power amplifiers on the bench looking a little forlorn.

Fixing the FP6400 : March / April 2020

The FP6400 had a failed channel, which allowed cross check from one channel to another, it also proved that the
power supply had not failed.

I still had to travel up the learning curve on how this class of amplifiers work, I will try to share that learning here

What is the theory of these amplifiers? How to they achieve efficiency?

Lets look at a standard Class B Amplifier and it's theoretical efficiency.

And that is 'all she wrote' as Dave from EEV Blog would say :

I MUST fill the page out, I collected so many scope traces and spent so much time fining this thing.....! ( AG Nov 20 )

I can always be emailed with the hex file for this chip at w e b 2 0 a t i w e u a d 0 t com