What did I do? -- FlexMod P3

Hi all, longtime lurker, first post.

Having trouble with a FM + M140 Diode from DTR. Using a 12v/28A power supply. Have the M+ wired through resistor to V+, and interlock on a switch. Got everything wired and the diode worked just fine at 500ma. Started to turn current up in small increments. At about 700ma, the red light on the FM illuminated. Even after turning the current back down to where I believe it was, the light is still on. Have I blown my diode? After unsoldering the diode, no continuity is show on the diode through a DMM. Should there be? Can't seem to find a definite answer, although I could be missing it. If I hook the DMM up to the FM to measure for current, as instructed in the manual, I get no current, and a red light. The fuse on the FM doesn't appear to be blown. I have measured the PSU voltage when turning the interlock on, and it doesn't appear to drop. Really hoping that it's something obvious, and I haven't blown anything. Thanks for the help.

FarmBoy said:

Have the M+ wired through resistor to V+

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Although the MOD input probably has protection, it's only meant for 5V, not 12V. That may have been the reason for the failure. Switch to a voltage divider for future projects.

FarmBoy said:

no continuity is show on the diode through a DMM. Should there be?

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That depends on the voltage your DMM uses for continuity. In most cases, the answer is no.

Retest your diode on another driver. You can also use a resistor to limit the current and hook it up to your 12V supply just for a test... depending on what resistors you have on hand.

Made a voltage divider, and set the M+ voltage at 5v. Still that little red light. Have a new driver on order. Hopefully the diode isn't burnt. Thanks for the help.