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New BC184L Oddity

 
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New BC184L Oddity

Post by crustytv » Mon Apr 20, 2015 10:40 am

Can anyone shed some light on what might be occurring here?

I removed VT602 a BC184L High gain transistor from my 3000 power supply to test. It passed the leakage test but I could not seem to get a Alpha/Beta reading.

I decided to open a brand new pack of replacements I purchased a few months ago. I identified the pin outs from the data sheet and decided as I always do, to introduce it to the B&K tester to confirm type (NPN/PNP) and pin outs, here is where it gets weird.

The test correctly identifies it as an NPN and the pin out matches datasheet however it also registers as NPN in an adjacent test where the emitter an collector swap places !!!! I tested an entire pack of 20 and all do the same, The original BC184L does not do this

confused :aab any ideas?

testran.jpg

 
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Re: New BC184L Oddity

Post by BluePilot » Mon Apr 20, 2015 11:09 am

CrustyTV wrote:The test correctly identifies it as an NPN and the pin out matches datasheet however it also registers as NPN in an adjacent test where the emitter an collector swap places !!!! I tested an entire pack of 20 and all do the same,

NPN is NPN, even if collector and emitter are reversed.

CrustyTV wrote:The original BC184L does not do this

Is it broken, different package, ...?

 
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Re: New BC184L Oddity

Post by TVJON74 » Mon Apr 20, 2015 11:37 am

Hi Chris,
That's probably normal.
Your meter is measuring two diode drops, one from base to emitter and one from base to collector. If you swap collector and emitter your still measuring two diode drops.
You could experiment with other npn devices to see if they behave the same way.

 
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Re: New BC184L Oddity

Post by Alistair D » Mon Apr 20, 2015 11:41 am

I would guess that the original transistor is open circuit B-E or B-C. That would also explain why you cannot get an Alpha/Beta reading.

Al

 
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Re: New BC184L Oddity

Post by crustytv » Mon Apr 20, 2015 12:18 pm

BluePilot wrote:NPN is NPN, even if collector and emitter are reversed.
Is it broken, different package, ...?

Right that shows my ignorance :ccb

TVJON74 wrote:Hi Chris,
That's probably normal.
Your meter is measuring two diode drops, one from base to emitter and one from base to collector. If you swap collector and emitter your still measuring two diode drops.
You could experiment with other npn devices to see if they behave the same way.

Ok Thanks Jon

Alistair D wrote:I would guess that the original transistor is open circuit B-E or B-C. That would also explain why you cannot get an Alpha/Beta reading.

Al

This 3500 PSU is driving me nuts, today I lost the 30V rail so went straight to the VT602 then got embroiled in this diversion.

Just installed one of the new BC184L and the 30V rail is back so yes it had died. Now I can jump back to the TV section and continue the pain of chasing the 58-65V rail as that is still hiding from me.

Thanks for all your input.


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