Who made this 2SA968 and is it safe to use?

[Steerpike]

I wanted to replace the two 2SA968's in my Revox amp since the originals have got hot and burned the pcb traces. Although they still work. I was hoping to use new ones with un-trimmed legs that I could space further from the PCB, with clip-on heatsinks, so I bought these.

Now I'm reading about sub-standard fakes. Does anyone recognise this T "trade mark"? I don't know that it's counterfeit per sè, since it isn't claiming to be a brand that it isn't. But is it safe to use?

It was bought from a large component supplier who should be trustworthy - but who can ever be sure!?

[Andrew Eckhardt]

I have no idea who made that but it sure looks funky and like they were hoping to pass it off as a Toshiba part.

[wg_ski]

It *is* a Toshiba part, and it looks exactly like A968's that I've salvaged from working equipment that was made in the 90's. If you're unsure, compare base-emitter capacitance to the known good.

[Steerpike]

Originally Posted by wg_ski

It *is* a Toshiba part, and it looks exactly like A968's that I've salvaged from working equipment that was made in the 90's. If you're unsure, compare base-emitter capacitance to the known good.

Thanks for that. The "T" looks a little wider & shorter than on other Toshibas I have, but the printing quality on this one is very good - so I was perplexed. The metal tab cutting is also a little rough - not as smooth & rounded as some To220s. Maybe late production runs on a tighter budget.
But the Cbe test will be useful - thanks for the tip.

I found that the pins from a molex conneter will work beautifully for extending the legs of the old transistors - so I can use them if need be. But the question is then... is it better to use proven old transistors - even if they've been run very hot, or new ones?

[wg_ski]

If a transistor has been run hot enough to cook a PCB, I'd replace it. I would also test any device that I didn't know where it came from.

You've also got to ask yourself - why would anyone bother to fake a run of the mill part that's not in high demand or volume and could be replaced by just about any modern TO-220 driver transistor? Just how many would they expect to sell? I can understand even cheap parts if they sell millions of them, and high-dollar stuff that restorers would insist on exact type number replecements (like 2SD424's in the old Adcoms).

[Steerpike]

I put in the new transistors - no explosions or fire so far. But now they are on a heatsink, whereas the originals were free-standing with no heatsinking at all. It's now possible to *just* keep my finger on them, so before they really must have glowed red hot.

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