Semiconductor PEAK testers

[rauldm]

I have two peak semiconductor testers, DCA75a and DCA55, I'm confused how DCA75 it works, I got a pair BJT's from fluorescent light, 1 is damaged, I upload a video where I tested with multimeter and two testers. DCA75 says component damaged is "right", is not detected like BTJ, DCA55 says is wrong.  I would get  comments about this...

[Kleinstein]

A damaged part that is not fully fused can behave odd, not like any common part. So depending on the tests used it may interpret is still some other part - likely with rather poor parameters. A broken transistor may still act as a diode or capacitor. Similar some odd parts (like very high gate threshold FETs or large (high trigger current) thyristors) may be identified wrong.

[tautech]

You might find some help info and links here to Peak Atlas products:
https://www.eevblog.com/forum/buysellwanted/special-offer-to-eevblog-forum-members/

[schmitt trigger]

All of the automatic semiconductor tester have "recipes" to determine the component type.

For instance, to determine whether a device is a JFET or BJT or Mosfet, one shorts the base or gate against the the emitter or the source.
If the UUT shows a current, the recipe would say that it is a JFET, because a peculiar JFET characteristic is a significant IDSS value.

Now imagine that the UUT is indeed a BJT with lots of leakage. Then at the ICES test, the tester sees the current, and determines incorrectly that it is JFET.

[rauldm]

Ok, but, is probably it happens because DCA75 it has more components variety? DCA55 says: "damaged component"

[maginnovision]

It may also have to do with the auto detect function. The dca55 appears to require specific hookup and the 75 figures it out.