(8FSA) Help me identify this SMD transistor

[rauloliv]

Hello all,

i have in hands a inverter welding machine to be repaired (DECA SIL-147 SIL-417) . I'm not very experienced on this but at first sight it would be just a problem of IGBTs replacement.

Looking closer i found one smd transistor (Q3) in s/c.
I don't have schematics and the case mark is not giving me any clues.
Its a SOT23 case with the inscription 8FSA



Edit:::::

Just found a similar welder schematic, but no references for the parts. The transistor should be a FET:





Can anyone help please?
Thanks

[t1d]

Well, I searched, hard, with all the tricks I know, but came up with nothing. I am sure you have checked the part number, but maybe give it another look.

Clean it well. Then, take a little bit of white heat sink grease, or medical zinc cream, and wipe it over the numbers. Sometimes, that helps them to stand out. Use good light, a magnifying glass and younger eyes, if available;-)

I will follow, this thread, to continue to try to help. One option is to identify what the part does and try to find a part that will meet the requirements.

[t1d]

Deca contact info:
© DECA s.p.a. Str. dei Censiti, 10 Falciano - Rovereta 47891 Repubblica di San Marino - Tel. 0549 910.711 - Fax 0549 908.360 - deca@decaweld.com

Is it SIL-147, or is it SIL-417?

[rauloliv]

Hi,

Its a SIL-417, thanks for noticing the error. DECA doesn't share schematics or any tech information, i contacted them.

I found a similar welder schematic and i am confident that the the component is a BSS123 mosFET.
Didn't replace it yet because unfortunately i found other complicated issues issues with this ...... 

Regards,

[TERRA Operative]

DECA doesn't share schematics or any tech information, i contacted them.

That's probably because they don't have that info to start with. It looks like a generic rebadged Chinese machine to me.

We never got board level schematics for our house brands when I was in the game, not even for the Flagship rebadged EWM models, let alone the Chinese ones. If even Cigweld and BOC can't get PCB schematics for their exclusive models, I wish you good luck.
It was usually a game of swapping boards, and only going to board level repair if things were obvious. (Like the period of time that EWM thought pop-riveting the heat sinks to vregs with the thin tabs was a good idea, then wondered why they all overheated and let the smoke out.....)