Makita diode failure

[Soundzrite]

I have a Makita 9 volt drill (M/N 6096D) that had the misfortune of putting the battery in reversed. Before I could react, the kickback diode in the switch (P/N 5310795 ~$50) burned up. The reverse battery voltage forward biased the diode and the MOSFET (2SK3271) but did not apparently burn up the FET. Sacrificial diode. The marking on the diode was S3V7D. I think that this is an obsolete or proprietary diode made by Shindengen. Their S3V series diodes are 3 - 3.5 amps, general purpose in an AX14 (important dimensions) package. The closest part I could find was the Diotec 1N5407 (Digikey 4878-1N5407CT-ND). I installed one of these and it appears to now work correctly. Don't operate the drill with the burned out diode. The back emf from the motor may toast the FET.

 

[Alec_t]

Welcome to maker.pro, Soundzrite, but you're a bit late to the party. This thread is nearly 13 years old!

 

[Harald Kapp]

Moved to new, separate thread.