Where to buy SIEMENS BD287 PNP

[Holt]

My trusted old Braun BVC 370 Hammerhead flash have been playing tricks on me, it fires all its charge at once instead of adjusting the output. while measuring various components, i discovered that there were no connection between base and emitter/collector on a BD287 PNP transistor even with the meter at 2Mohm.
I was happy, i had found the error! Well i didn't stay happy very long, i can find tons of datasheets, but not a single shop selling the damn thing, Can anyone help me please?

 

[Hero999]

If it's broken, it probably doesn't have to be replaced with the same transistor, once with a similar gain and equal or greater, GBWP, voltage and current ratings will do.

Do you know the test voltage of the meter? Lots of DVMs have very low test voltages so the can measure resistors whilst they're in the circuit. The base and emitter measuring open circuit on a DVM means nothing if the test voltage is < 0.6V.

You need to use a diode tester to ensure the transistor doesn't work.

 

[Holt]

I took your advice and measured it with a diode tester, and i measure something from base to emitter/collector when i connect neg to base, but nothing when i connect pos to base. shouldn't it be emitter in one direction and collector in the other direction (sorry if i am a bit vague, but English isn't my native languish )
PS: it could be diffcult to find a replacement, this transistor are according to the datasheed especially made for flash control

 

[Hero999]

No it's a PNP transistor so will look like two diodes with a common cathode at the base, an NPN  transistor is the other way round.

The transistor still might not be working properly, this test isn't perfect although it's now more likely the transistor does work and some other part has failed.

 

[Holt]

Thank you very much for your help!
I have now been measuring all transistors in the circuit, and they seem to be okay, but there are two thyristors in the circuit, a BRX46 and a BRX53, are there any way to measure if they are OK ?

 

[Hero999]

Not that I'm aware of, your best bet is to remove two of any terminals from the circuit and test them with an LED, switch, resistor and battery to check they turn on when triggered.