Strange Components

Strange Components
« on: May 13, 2019, 09:59:34 am »
I am identifying the internal components from a hybrid power module, BI 72-727-003 (nowhere to find schematics about it) using Huntron Tracker 1000, all pins and its internal components were identified correctly (diodes + power MosFET), except for two isolated pins, they show the following Huntron trace in Low range.   I could only imagine it being generated by two resistor and a diode (50Ω resistor in parallel with a series of diode and 20Ω resistor). This could be the MosFET gate current limiting, the 50Ω for charging and the diode+20Ω for discharging the gate.  In Med scale it shows a short circuit.  I simulated the trace angles with a 100Ω trimpot. Any hint?


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Re: Strange Components
« Reply #1 on: May 14, 2019, 02:37:28 am »
I had a look for data on this IGBT module, but like you couldn't find any.
The Tracker 1000 has a limited range of stimuli, unlike the ProTrack, and later Trackers.
So on low range shows a good "diode knee", but jumping up to the Mid range switches the device hard on so shows what appears as a short, or the Trackers 1000 big jump in voltage on the Mid range cannot show the difference between a low value resistor across a diode or MOSFET switching on.
Perhaps Curtis will confirm or correct my diagnosis!!
« Last Edit: May 14, 2019, 02:44:52 am by jvthorsley »


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Re: Strange Components
« Reply #2 on: May 16, 2019, 08:58:05 am »
James is correct about the jump in voltage and resistance when going from Low (54 ohms) to Med (about 27K ohms). LOW would be the only usable range in this case. Also, the LOW range open signature shows a 45 degree angle further complicating the analysis. You definitely have a semiconductor in there with low value series resistance (the vertical part of the trace) and higher value parallel resistance (the horizontal part of the trace).
The most important troubleshooting tool is your eyes.