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

[Chuck Guzis]

On 03/01/2015 11:53 AM, tony duell wrote:

> Are there any discrete transistors for this? I know the diagram in the
> service manual shows them, but that is a different version of the motor
> and the LB1620 can normally drive the windings directly. I don't remember
> seeing them in the photos.

I found the datasheet for the LB1620 and apparently the thing is 
perfectly capable of directly driving the motor windings.  I note that a 
small (10uF to 47uF) electrolytic is specified between each of the 
windings and +24 Vcc.  Were one of those to short, that would indeed 
have nasty consequences as the output of the LB1620 is via a 
complementary pair operating totem-pole fashion for each phase.

So, in absence of a readily available LB1620, I'd start with the 
per-winding caps.

--Chuck