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Please Help, Unknown Transistor

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daveintdbn

New Member
Hi there. I'm new to this forum.
I'm trying to rebuild a Regulator/Rectifier Circuit that I got off a Kawasaki 440 Jetski. The Circuit board was encased in resin so in order to get to the electronics I had to hammer the resin off. I took the circuit board to a few electronic stores around my ared (Durban, South Africa) and no one can tell me where to get this transistor, google doesnt even seem to know. It has a number on it, I think its a toshiba. It has number: SF3A14 and then either 1K or 7K under that. Please can you guys try help me to identify this transistor so I can get a replacement.

PS: These electronics aree about 31 Yrs Old!

Thank you
 

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bailey45

New Member
Looks like you need a bit more than a new transistor. A simple solution here may be to use a new regulator from a more current model of jetski. A typical regulator has three connections +, - and the control to the alternator. If the board is also rectifying then there a re two additional connections which are interchagable. On a lot of models the part is electrically interchangable, look for a model with the same number of leads as you existing unti that will fit mechanically.
 

Chippie

Member
Can you determine if its PNP or NPN?

I recall reworking a regulator for a work colleague many years back and used a BU126....Once rebuilt the generator worked fine
 

daveintdbn

New Member
Thank you so much for your help Bailey45 & Chippie, I really appreciate it
This regulator has two AC inputs in from the stator coil, one ground and one positive DC.
I actually tried a regulator from an old Johnson outboard motor and it seemed to work fine.
it pushed out 3.4Voltd DC when Just cranking. BUT.... I'm not the type of guy to give up.
I found this website SF3B14 Semiconductor (Transistor, diode, IC) Cross reference
It is a SF3B12 instead of a SF3A12, do you guys think its a big difference? the suggested replacement part is a 2N4101, BStC05 etc...
Is there any way to determin if its a PNP or NPN?
If I dont come right I'll try the BU126 if I can get my hands on one.
 

hdc090360

Member
Transistor?

I wonder if that actually is a transistor? Most of the Japanese transistors of the time started with the prefix 2S. - 2SA and 2SB being PNP and 2SC and 2SD being NPN.

I think you will probably find that it is an IC of some variety.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
I wonder if that actually is a transistor? Most of the Japanese transistors of the time started with the prefix 2S. - 2SA and 2SB being PNP and 2SC and 2SD being NPN.

I think you will probably find that it is an IC of some variety.
You're more likely to find it's an in-house number, so effectively meaningless.
 

mneary

New Member
After you identify the burned resistors and smashed diodes and reconstruct the burned PC board, the function of the mystery component should be fairly easy to figure out.
 

Mr RB

Well-Known Member
It's a standard Toshiba partnumber for a 3 amp SCR ;

SF3B14 100v 50Hz 3A Igt=25mA Ih=30mA
SF3D14 200v (rest same as above)
SF3G14 400v (rest same as above)

The SF3A14 is not listed, but it's just a lower voltage version, probably a 60v version. You could use any of the SCRs above, or equivalents 2N4101, or BT152.

And as for fixing it.... It looks kinda broke. :eek:

Just buy a cheap 12v regulator from any small single phase motorcycle at the local wrecking yard.
 

solis365

New Member
trying another regulator board may work, but you could also trace the wires on the PC board and draw up a schematic of what the circuit was. then it will be easy to figure out what it did and how to recreate it.
 

hahamiki

New Member
Hello

I rebuild a Regulator for motorcycle GL1000 GoldWing 1976. Under compound I found same element SF3A14. In all internet the name was found in this forum only.
But I have a wiring diagram for this regulator. It's tiristor!!! with 50 Om resistor between cathode and gate.

Good luck!
 

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