MicroSquirt.com read only forum (Jan.15,2018)

My microsquirt's case was connected to an ungrounded engine block, while a team member repeatedly tried to start the engine. Basically the case was at 12V, while everything else was connected properly. Now my 5V regulator is reading strangely. The 12V in reads 12V, the ground pad reads 9.58V, and the 5V output reads 12V. The polyfuse passes the diode test on my meter. The D1,D2,D3, all read the same as my backup uS.

From this I assume I need to replace the 5V regulator. but I am not sure why I would see 9V on what I thought was tied to ground, could I have burnt the lead to ground and not see it?

Geoff

If you are reading 12 volts on the Vref line then all of the semiconductors on the uS are toast (they can only tolerate 5.5V or so, anything higher and they destruct). The newer boards have a 5.6V zener on the 5 volt line to help protect on overvoltage - however it will not protect when the uS is the ground path for a starter. But these things happen....

Send me an email (bbowling@earthlink.net) and I will get you fixed up.

- Bruce