MJ15003 hFE values

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25-Dec-2019 04:43 PM

Mark B

Mark B

Posts: 12

Hi

Im currently working on a 606 and I’ve stripped out the main power transistors for testing.. they all check out as working with a peak instruments transistor tester but have hFE values of  45, 70ish and 100ish in pairs (ie 2 of each hfe value approx) ... this is within spec but wonder if this indicates some degradation or actually is some pair matching between the 2 groups of 3 transistors, is one of each hfe range in each triplet.

Overall I’m fine replacing them all but don’t want to if they are good to improve matching with the other channels board. Do folk think they should be ok or should I replace them? 

any thoughts on this would be gratefully received 

have a nice christmas

Mark 

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27-Dec-2019 04:07 PM

Stefaan

Stefaan

Posts: 628


Hello,

The Hfe doesn't matter as the amplification factor depends on the resistors around the transistor and the feedback, the transistor is not in "free-run".

As long as it is within the specs of the datasheet the transistor is OK.

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27-Dec-2019 05:36 PM

Mark B

Mark B

Posts: 12

Hi Stefan

thanks that’s exactly what I needed to know and I’ll go ahead and finish the build now. Very much appreciated

happy new year

Mark

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