Replacement for MJ13091 NPN Bipolar Power Transistor in TO3

[MadTux]

Hi,

Anyone knows a common, new replacement for a MJ13091 NPN Power Transistor in TO3?
Data sheets in attachment.
Requirements: Vce=700+ V, Ic=15+ A, 170W Power Dissipation, TO3 package,

I'm repairing a HP-8662A and one of it's faults is a fried MJ13091 on A7A3 board. Since the design is about 30 years old, MJ13091s are a old, rare, a bit pricey and only available from US ebay now, so quite costly to ship to Europe.

So I'm quite sure that there are better transistors available now. Maybe someone (with SMPS design knowledge) knows a better replacement that is more common and maybe a bit cheaper?

Thanks

[SeanB]

2SD2689 seems like a good candidate, if it is only being used as a SMPS switch.

http://dalincom.ru/datasheet/2SD2689.pdf

Not going to work in a linear application, but as a saturated switch even the venerable BU508/ BU508D/ BU208/ BU208D will do in many uses. Those at least will do 100W plus dissipation, and have a peak current of 15A.

[MadTux]

Thanks for the list, I'll search for the datasheets and look if I can find some of them cheaply on ebay europe. There's some more damage on the board, the reverse protection diode and the fuse on the base are blown too.

Here's a decapped pic of the toasted MJ13091, big black hole on the emitter.

[MadTux]

The newer revision board from my other working 8662A that I used to isolate the fault uses two MJW18020 in TO-247 package in place of MJ13091. Even more badass transistor than MJ13091: Vce: 450V, Ic: 30A, 250W power dissipation.

Too bad they aren't available as TO3, as the heat sinks and collector terminals are designed for TO3 on that old board. And since blown transistors seem like a common fault in 8662A PSU, it's probably a good idea to get most badass transistors as replacement, so they never get toasted again.

[MadTux]

So, hunted the net for badass transistors in TO-3 package for a while, here the results:

BUX-48A (NPN, 850V, 15A, 175W)
NTE-386 (NPN , 500V, 20A, 175W)
NTE2319 (NPN , 450V, 15A, 175W, fastest one)
BU508A  (NPN , 700V, 8A, 175W)

MJ-10015, MJ-10016 (NPN Darlington, 500V, 50A, 250W)
MJ-10024, MJ-10025 (NPN Darlington, 850V, 20A, 250W)
MJ-10000, MJ-10001 (NPN Darlington, 850V, 20A, 175W)
NTE98 aka MJ-10009 (NPN Darlington, 500V, 20A, 175W)

Found some BUX-48A and MJ-10016 Darlington-transistors on ebay quite cheaply, don't know whether the high current gain of MJ-10016 (hFE between 60-600, compared to hFE of 8 of original MJ13091)  causes any trouble in the SMPS, but I guess more current gain is better than too little, because high current gain makes the SMPS switch faster, so less heat in transistor.

[MadTux]

Kill count, so far:
Q-4
F-2
CR-5
C-1 (nice brown color , maybe it failed first and took the transistor with it when it shorted out, who knows)

Haven't tested Q4 driver circuit so far, so stay tuned for more kills

[codeboy2k]

Here's a decapped pic of the toasted MJ13091, big black hole on the emitter.

That will just buff right out ...

[SeanB]

SOA exceeded by a little on that unit.

Do not use a darlington transistor, it will blow up in a few seconds as it is way too slow, and takes too long to turn off in a SMPS. A gain of 8 is more than enough, base current here is 1A or so, more than enough. The circuit needs the transistor to turn on fast and more importantly turn off very fast, which a darlington is never going to do.  The drive circuit has active turn off, and will need a transistor meant for TV line output or SMPS use, where high turn off voltage and fast switching is needed.

Look at a BU508D, as it has the integral diode, and is designed for switching application, so will drop right in there in both cases. Change both the transistors at the same time, and change both C3 and C4 along with C1 and C2.  use 10uF 63V caps for C3,4 and 22uF 400v for C1,2. A TO247 or TO218 case is designed to be a drop in replacement for a TO3 transistor, using the base and emitter lead holes direct, and the tab as the collector connection. If you get the ISOWATT version you just need to use a link wire to the collector lead to the top of the case if you have TO3 hardware with a collector bolt. That version just needs heatsink compound, the case isolation is good to 1.5kV.

[motocoder]

alltransistors.com is a good site to use for finding equivalent transistors. Example:

http://alltransistors.com/crsearch.php?mat=Si&struct=NPN&pc=175&ucb=750&uce=450&ueb=6&ic=15&tj=200&ft=&cc=350&hfe=8&caps=TO3

[Jay_Diddy_B]

Kill count, so far:
Q-4
F-2
CR-5
C-1 (nice brown color , maybe it failed first and took the transistor with it when it shorted out, who knows)

Haven't tested Q4 driver circuit so far, so stay tuned for more kills

@MadTux,

Were you able to repair this power supply?

I have a similar unit with the same damage.

Which transistors did you use?

Regards,

Jay_Diddy_B

[MadTux]

Got 2 broken ones working again, third one keeps blowing transistors and is still on my repair stack.

I guess the  input capacitors on the +/- 160V rail are bad on #3, but didn't get around to order new ones and replace them yet.
Also a bit disappointing to debug such one time events without a good digital scope. 

For repair, I used BUY69A transistors (relatively cheap here in EU), they are working fine since then.
If they keep blowing, the problem is most probably somewhere else.
Don't forget to check the 0.4A fuses, they usually blow along with the transistors.
If you want full high quality manual, I can mail you, if you want.