Re: Infamous D180 is it good or bad.


Eric
 

Thanks for all those they weighed in on the TD issue. I was able to get back in to the lab and retest the TD this evening using Dennis’s settings for the curve tracer. After lots of reading and thinking today I have learned a few things.
1) I was WAY overly skittish given the rarity of the part and partly for my lack of knowledge I did not want to hook the diode up to a power supply directly especially this one as replacement are rare and very expensive so if it was good I did not want to fry it.
2) My measurement setup was FAR from ideal. No there were long leads ALL over the bench. But I had ran collector -> amp in -> meter -> amp out -> to TD+ -> TD - -> emitter on the 577. The really high resistance value was done before I asked a question here on the group and was selected for my being very skittish with this TD also was a problem.
3) The message from this morning was to try and clarify my post from last night no additional testing was preformed this morning.
4) The oscillation noted from the photo this morning. I was so intent that I did not notice what was going on it was caused by the DMM switching ranges and what I am assuming shunt resisters as well
5) In NPN mode the curve tracer is NOT DC it is pulsed dc the meter would never be able to accurately measure the dc level output from the curve tracer. Trust the curve tracer to do its job/

Learnings

Let the curve tracer do its job. It is a wonderful instrument that I need to trust and not try and second guess it. It will give me an accurate picture as to what is going on.

There will be 2 pictures posted after this The good news is the diode seems to be in wonderful shape and I am now getting a curve that I expect out of them. Most of my errors this time were between instruments and chair. Knowing that the diode is good at this point leads me down a path that the diode is not getting enough drive so it seems I have a current issue on the 284.

I will endeavor to trust my self and my instrumentation more in the future.

https://groups.io/g/TekScopes/album?id=248216

Eric

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