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

Enrico Lazzerini enrico.lazzerini at email.it
Sun Mar 1 15:12:06 CST 2015

Well, for 1st thanks for your suggestions.
I tried to desolder any sigle pin of each component between +24vdc and
ground from almost one side, but the short circuit remains. So the only pin
that remained are those of LB1620. I ordered 2 from ebay. It takes almost
2/3 weeks for the shipping from usa to me.

The pcb I have THERE IS NOT that described in the last page of the
maintenance manual. IT NOT have power transistor to drive the motor.
The only one transistor on the pcb not appear to be a power transistor 

Connectred to the LB1620 there are 3 electrolitic caps of 22microf 15Vdc, 3
very small resistor 6,8ohm, and 3 ceramic caps of 4700picofarad. The smoke
seem to come just from one of there last one, but it appears clean.

I will try to desolder the LB1620 tomorrow to check if there will be more
the short circuit between +24vdc and the ground.

3 things:
1) changing the lb1620 not means that could be more components broken even
if the short circuit will not any more
2) what kind of socket has the LB1620. it is not dual in line DIP. Is it
exist a socket for it? Or have I to solder 2 line of pins separate by them?
3) Why do not use a graetz bridge to power this pcb? Almost inverting the
power would save the pcb forever....



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