need replacement transistor

[xelectech]

Hi,

hoping someone can ID or suggest a replacement for one found in an antec EA-500 psu:


6 4 7
6 L 4

e c b

It's a TO-92 case, the second line of #'s are spaced more widely. It's in the 5vsb ckt., I busted a lead off trying to remove some of the tan glue from it's legs.

[SteveNielsen]

Re: need replacement transistor

Google

It's probably a 2sb647

e c b is the pinout; emitter, collector, base

[budm]

Re: need replacement transistor

How is the Transistor connected to other components? Good clear pictures of both sides of the board?

[xelectech]

Re: need replacement transistor

Google

>I did, tried bing, yahoo, digikey and mouser also, as well as alldatasheet

It's probably a 2sb647

>that may be it - at least they are both pnp's

e c b is the pinout; emitter, collector, base

Thanks Steve

[xelectech]

Re: need replacement transistor

How is the Transistor connected to other components? Good clear pictures of both sides of the board?

My good camera is down right now, it may be able to take a better pic of the bottom - the emitter was connect to R601 on the bottom of bd., (a surface mount one), the collector was connected to R602, (15 ohms) near the heatsink, right in the area where the purple wire is.

I removed a 220uf 16v cap, which reads ok in esr and capacity. The transistor tests ok too, both diode junctions only read one way, about 640mV.

Thanks Bud

[SteveNielsen]

Re: need replacement transistor

Their solder-wave must have been running cold, that blobby shit would have never made it past me when I did QA.

[xelectech]

Re: need replacement transistor

Their solder-wave must have been running cold, that blobby shit would have never made it past me when I did QA.

It is pretty ugly, rather hard to make out which component's leg is sticking through where -
I don't think it's been worked on before, I put all the scratches on it trying to get rid of some whitish powdery stuff that was between the traces in several places.

[japlytic]

Re: need replacement transistor

With Japanese transistor types, "2S" is usually omitted on the device markings, and I have seen some which also omit A/B/C/D markings.

[xelectech]

Re: need replacement transistor

With Japanese transistor types, "2S" is usually omitted on the device markings, and I have seen some which also omit A/B/C/D markings.

Thanks for the info. I guess a comprehensive cross-reference book is a thing of the past now.

[stj]

Re: need replacement transistor

put the old one on a tester to see if it's npn or pnp etc.

[xelectech]

Re: need replacement transistor

Their solder-wave must have been running cold, that blobby shit would have never made it past me when I did QA.

Hey Steve, just wondering can you tell me if the surface-mounted components are put on the board before, or after, it goes through the wave-soldering operation?

[vinceroger69]

Re: need replacement transistor

A good video showing wave soldering
https://www.youtube.com/watch?v=Ap-HY7qP9zE

[budm]

Re: need replacement transistor

At :34~36 you can see she twisted the black heatsinks for the SMD ICs, so the SMD components were already went through the SMD process before the wave soldering process.

[xelectech]

Re: need replacement transistor

A good video showing wave soldering
https://www.youtube.com/watch?v=Ap-HY7qP9zE

Thanks, I'll check that out next time I get to the library.

I have seen 2 different setups in operation, one at Spacelabs (a biomedical equipment mfgr.) in the early '80s, and another in the mid-80s at a dental xray equip. mfgr. - don't know when surface-mounted stuff came on the scene, but there wasn't any back then that I'm aware of.

[xelectech]

Re: need replacement transistor

put the old one on a tester to see if it's npn or pnp etc.

Kinda hard to do that, one of the legs is busted off flush - still possible to test the diode-junctions, though, it's a pnp.

[SteveNielsen]

Re: need replacement transistor

Where I worked they were just starting to test running boards with smt parts thru the solder wave and trying out different glues. This was quite some time ago and smt parts were not widely used yet.

[stj]

Re: need replacement transistor

you do wave-solder smd
to do it you need 2 things.

1: you need to glue the parts down - annoys the hell out of me when i need to replace them!
2: on chips you need larger pads on the end the wave flows towards to catch the solder before it bridges anything.
you often see an arrow on these boards indicating the direction of the wave.

[xelectech]

Re: need replacement transistor

you do wave-solder smd
to do it you need 2 things.

1: you need to glue the parts down - annoys the hell out of me when i need to replace them!
2: on chips you need larger pads on the end the wave flows towards to catch the solder before it bridges anything.
you often see an arrow on these boards indicating the direction of the wave.

Interesting! Thanks

[xelectech]

Re: need replacement transistor

Looking for a suitable replacement still - I found a similar tranny in a psu (guess I should have mentioned that the broken one is in either a to92-L or to92-MOD, but I didn't know at the time), here's a couple datasheets, the 2sb647 being the original and the ksa928a being similar (but is it similar enough?)

Not sure anything attached, can't see it in the preview...

Nope, couldn't load the links - anyway, does anyone know if these two transistors are close enough that I can use the ksa928a in place of the 2sb647?

Thanks for any insight...

[tw2005]

Re: need replacement transistor

http://alltransistors.com/crsearch.p...e=60&caps=TO92


Type Designator: 2SB647

Material of transistor: Si

Polarity: PNP

Maximum collector power dissipation (Pc), W: 0.9

Maximum collector-base voltage |Ucb|, V: 100

Maximum collector-emitter voltage |Uce|, V: 80

Maximum emitter-base voltage |Ueb|, V: 0

Maximum collector current |Ic max|, A: 1

Maksimalna temperatura (Tj), °C: 125

Transition frequency (ft), MHz: 70

Collector capacitance (Cc), pF:

Forward current transfer ratio (hFE), min: 60

---------------------------------------------------------------------------------------

Type Designator: KSA928A

Material of transistor: Si

Polarity: PNP

Maximum collector power dissipation (Pc), W: 1

Maximum collector-base voltage |Ucb|, V: 30

Maximum collector-emitter voltage |Uce|, V: 30

Maximum emitter-base voltage |Ueb|, V: 5

Maximum collector current |Ic max|, A: 2

Maksimalna temperatura (Tj), °C: 150

Transition frequency (ft), MHz: 120

Collector capacitance (Cc), pF: 48

Forward current transfer ratio (hFE), min: 100