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

[Enrico Lazzerini]

I thought to this with a 7808:
https://www.dropbox.com/s/ekj0bftrh86nhsa/PowerOK.jpg?dl=0
to test before to resolder the new LB1620.

Thanks for the kind support of all of you.
Enrico

-----Messaggio originale-----
Da: cctalk [mailto:cctalk-bounces at classiccmp.org] Per conto di Brent Hilpert
Inviato: martedì 3 marzo 2015 22:41
A: General Discussion: On-Topic and Off-Topic Posts
Oggetto: Re: How to save two Mitsubishi M2896 drive (spindle motor smoked!)

On 2015-Mar-03, at 11:00 AM, Enrico Lazzerini wrote:
> Well, on the zener i measured 12,45V. So it is a 12V I think. Not 15V as I
> previous supposed. It power the pins as I written so :
> 
> About powers:
> LB1612 pin 19 datasheet says 8-14VDC
> TC1642P pin 16 datasheet says 5-9.5VDC
> C358C pin 8 datasheet says until +32vdc
> 
> I could try to substitute the zener with a 7808 ic 1W.
> This could keep all is not warm and protect. RIGHT?

8V of a 7808 may be low/marginal for the 8.5V min specified in the LB1620
datasheet (at least in the Sanyo one I'm looking at).

You could add a diode or two in series with the GND leg of the 7808 to raise
the voltage to around 8.6V (1 diode) or 9.2V (2 diodes).
(cathode to GND, ordinary 1N400x for example).=