D10 blown, I need help

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09-06-2011 | 04:01 PM

absRTP

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D10 blown, I need help

Last edited by absRTP; 09-09-2022 at 04:55 PM.

09-06-2011 | 04:04 PM

Braineack

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D10 is on the 5V power circuit... you have short between 12v and ground.

c11 is on the crank signal input...maybe that's where the 12v is coming from? bad jumper? check r13. check between c11 and the opto, and check between c11 and optoout.

09-06-2011 | 06:06 PM

absRTP

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09-07-2011 | 12:09 PM

Matt Cramer

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The most common cause of continuity from 5 volts to ground is a blown D19.

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09-07-2011 | 02:02 PM

absRTP

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Last edited by absRTP; 09-09-2022 at 04:55 PM.

09-08-2011 | 02:07 PM

absRTP

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Last edited by absRTP; 09-09-2022 at 04:55 PM.

09-08-2011 | 02:13 PM

absRTP

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09-08-2011 | 02:18 PM

Braineack

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it'll be close. it appears that would be the diode that protects from any flyback on the VCC. so if it ever spikes above 5.1v it'll clamp to ground. doesnt leave a lot of room for tolerances...

09-08-2011 | 02:22 PM

absRTP

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Last edited by absRTP; 09-09-2022 at 04:55 PM.

09-08-2011 | 02:27 PM

#10

Braineack

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Honestly, I dunno.

Last edited by Braineack; 09-08-2011 at 02:43 PM.

09-08-2011 | 02:34 PM

#11

absRTP

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09-09-2011 | 10:43 AM

#12

Matt Cramer

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Quote:

Originally Posted by absRTP

Obviously, I took of D19 and put a 1N4733A in place to test it and finally, there is no more continuity between ground and 5V.

Now, I don't want to powerer it up until someone tell me it's safe to do so with a 5.1V zener instead of a 5.6V one.

Thank you all!

It isn't safe, at least not for that diode (the rest of the MS would be fine). If that zener diode's tolerances are a little off, you could have a 4.9 volt zener in there. Going the other way, to a 6.2 volt zener, is perfectly acceptable.

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