Transistor question

[Gazucha]

 Hola,

  I have a project which has two 450V 10A NPN transistors in the circuit and I haven't found a suitable data-sheet.
 
 One is stuffed. Which is being changed.
 On a diode test, the other reads 0.385 and 0.502 when measured, which seems to me to be a large difference.

 So, the question is,

  is the transistor still within functionable parameters with those readings, or could it possibly fail alongside a new partner?

 Cheers.

[Alana]

First - do you mesure it desoldered completely?

[Gazucha]

 Hi,

 Yeah, desoldered completely. On the bench.

[Gazucha]

 The reason I ask is that if those readings were on, say a BC547, then I would consider it failing...

  and the high voltage, high amperage, transistor field is not my comfort zone.

 I would imagine it would work, but unless someone knows different, then I'm not mad on having such an imbalance in the transistors, as I am fairly sure that the new transistor (C4237) will read 0.600+ on from B to both C & E pins.
 

[Alana]

I'd do the very same thing - if BE and BC are so different its usually faulty. To be sure try to turn a light blub with that transistor - if it works it may be ok but i doubt that.

[Gazucha]

Update...

 When tested in the shop, one new 2S C4237 tested 0.548 & 0.445 and another 0.502 & 0.435, so I decided to take a chance and only buy one, the one which tested closest to the existing transistor (which is actually testing 0.514 & 0.397).

 When I saw that the brand new ones also have a large difference in measurement, I realised that perhaps the original transistor is not as bad as imagined?
 That coupled with the fact that to install the 2SC4237 entails drilling and a bit of open-heart surgery,  it seemed prudent to start with the one that is 100% failed.

[Paul Price]

With the majority of bjt's there is most common a difference between c-e and b-e readings, and this reading varies with the make and model of meter making this measurement.