two dead inverters

[shovenose]

Re: two dead inverters

And the power supply you're feeding it with never shuts down?

If you're never getting the DC bus voltage, it's possible the 12V MOSFETs aren't being driven.

First, check between that eyelet and the chassis for shorts. Shorted rectifiers will keep the DC bus from coming up.

At this point, you're gonna have to pull the board and check things. You'll probably be doing a few "hot tests" too.

Don't forget to look for that 7805/78L05, and make sure you're getting +5 out of it. Its 12V feed should come from the "power" switch. That's right- the entire 12V side of that thing always has power. The switch just supplies control power to the 12V PWM and opamp(s).

Have "fun."

Nope the 750W never shuts down and maintains steady ~12V on outputs.

[kaboom]

Re: two dead inverters

OK, I measured from the "eyelet" on the board to chassis... never gets any voltage whether it's off or on.

Nope the 750W never shuts down and maintains steady ~12V on outputs.

Well...

It turns out that I gave you some incorrect info. The eyelet actually appears to be a GND point. That should've occurred to me, as it's easier to implement the current sense (with shunts) in the low side, rather than the high side. No wonder you measured nothing, you were trying to get a "reading" between two GNDs!

Now measure this again, looking for "bus voltage."

Put your black lead on the eyelet, and probe the tabs of the 8 H-bridge MOSFETs. At least two should have the 160-170V DC. Most likely four will.

Sorry for the "confoosion."