Touching one lead to heatsink and using other to touch individual legs of output mosfet devices in F-5, one leg is quiet on each, other two legs buzz...is this correct? I would have bet money they used to all three be quiet, but it has been since initial build and that's been a few years back.😕 I have recently been rewiring a thing or two...
Russellc
Russellc
you are not only meassuring mosfet to sink if the fets are in the curcuit and wired up. you are messuring from mosfet pins to ground in the curcuit. connect a speaker and i bet it will buzz from the third pin too 🙂
That's sort of what I was thinking...
So third pin that was quiet is a test of mosfet to sink continuity? Or am I just fooling myself...I guess the time to test is before attaching to board...
Russellc
the bet the Third pin is going Direct to the output. Connect a speaker and you only have 3-8ohm between that pin and ground/sinks. that will tripp the buzzer.
I'll try when I get home. I'm sure what I remember is testing right after tightening to heatsink, before attaching board and soldering.
Russellc
the three pins of the output MosFET are all different.
Two are isolated from the the backplate and the middle Pin IS the backplate.
The Middle pin should be infinite resistance to the heatsink.
Two are isolated from the the backplate and the middle Pin IS the backplate.
The Middle pin should be infinite resistance to the heatsink.
Thanks , that makes sense. I,m sure when I first measured them, only the mosfets were attached. Now only one leg is quiet now that it is assembled.
Russellc
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