How to save two Mitsubishi M2896 drive (spindle motor smoked!)

[Brent Hilpert]

On 2015-Mar-02, at 1:17 PM, Enrico Lazzerini wrote:

> Connecting the bigger resistors and the zener D102 the voltage on this last
> one is 12,45Vdc. This one is direct connected to:
> LB1620 pins 9,12,19
> TC9142P pins 4,12,16
> C358C pin 8
> Then LB1620 pin 4 = +24Vdc
> 
> Is in this way that TC9142P could be burned?

Well it is excessive, so you wouldn't  want to run it at that level for long periods. Whether it (the 9142) has failed already is an open question.

Did you test the zener and big R together out-of-circuit, or with the other ICs still connected?
12.45V sounds low for a 15V zener (if that's what it is), so I wonder if something else is pulling the V down.

I hope the hall sensors are OK, I don't know how much variation on supply V they can tolerate.