I have been offered the chance to buy a couple hundred of these "Sumitomo" 2SA1302 and 2SC3281.
I have read that Sumitomo made and possibly still makes lead frames, but I've not read about them making these transistors back in the late 1990s. They were obtained by the seller from an amp manufacturer about 15 years ago, but I don't know if they were ever used in production, or if they are legitimate.
There are "NOS" Sumitomo 2SA1302 and 2SC3281 for sale on the auction site, but they don't look legitimate to me.
Anyone have insights? Thank you!
I have read that Sumitomo made and possibly still makes lead frames, but I've not read about them making these transistors back in the late 1990s. They were obtained by the seller from an amp manufacturer about 15 years ago, but I don't know if they were ever used in production, or if they are legitimate.
There are "NOS" Sumitomo 2SA1302 and 2SC3281 for sale on the auction site, but they don't look legitimate to me.
Anyone have insights? Thank you!
I don't know if it helps but I bought boat loads of used Toshiba 2SA1301 and 2SC3280 pulls from used electronics sold on AliExpress. Once I found a good source I went back until he ran out. Got them for a song and the seller shipped fast. Old date codes vintage transistors. Not perfect looking in some cases and the leads were short or broken in some cases but legit devices.
I bought so many I have sorted them into complimentary gain-matched PNP and NPN devices.
This type of buying is a real option but not for everyone.
I bought so many I have sorted them into complimentary gain-matched PNP and NPN devices.
This type of buying is a real option but not for everyone.
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Current production at Sumitomo is wafers and Blu-Ray lasers, no devices.
Like above, buy a small quantity to try / check before buying a big lot.
A couple of hundred from new production will be of more consistent quality, less issues with matching and sorting, a lot of time will be saved.
The processes have improved, corrosion might have occurred on old parts.
If you get them at 2x scrap price, try.
I would pass the opportunity.
And what will you do with them?
Like above, buy a small quantity to try / check before buying a big lot.
A couple of hundred from new production will be of more consistent quality, less issues with matching and sorting, a lot of time will be saved.
The processes have improved, corrosion might have occurred on old parts.
If you get them at 2x scrap price, try.
I would pass the opportunity.
And what will you do with them?
Perhaps those were Toshiba made, and made for Sumitomo. If they made equipment that those parts went into (and would be the only factory-authorized replacement). In the same way as Motorola parts were marked Krell, Crown, or Peavey.
1999 would have been right around when Toshiba quit making C3281 and replaced it with C5200. I know Digikey had both for a while back then, but they were phasing the C3281 out.
Buy and try, of course.
1999 would have been right around when Toshiba quit making C3281 and replaced it with C5200. I know Digikey had both for a while back then, but they were phasing the C3281 out.
Buy and try, of course.
You will never be happy with them unless you are 100% certain they are genuine.
Fwiw the fact that it seems to have lettering that doesn't look quite straight would put me off. Also the wording has MO at the end of SUMITOMO looking bigger than the other letters.
Not saying this is or isn't genuine but it looks more correct.
Fwiw the fact that it seems to have lettering that doesn't look quite straight would put me off. Also the wording has MO at the end of SUMITOMO looking bigger than the other letters.
Not saying this is or isn't genuine but it looks more correct.
Real vs fake ThermalTrak NJL0281\0302
https://c10.patreonusercontent.com/...=QrktHcRMPuJv34YA9VPJFmptdYx7j-NN-gTKqkMaBd8=
https://www.patreon.com/posts/kak-otlichit-ot-89000460
https://c10.patreonusercontent.com/...=QrktHcRMPuJv34YA9VPJFmptdYx7j-NN-gTKqkMaBd8=
https://www.patreon.com/posts/kak-otlichit-ot-89000460
i rememebers ZENmods comment for MOSFETs. 😉
a complete amp is with housing and powerfull PSU very expensive and you save money at the transistors?
that is the reason why i trust just mouser , digikey...
i need minumum 10 pcs for selection of push pull for each rail side so it cost about 3-5 euro per rail.
kr
chris
a complete amp is with housing and powerfull PSU very expensive and you save money at the transistors?
that is the reason why i trust just mouser , digikey...
i need minumum 10 pcs for selection of push pull for each rail side so it cost about 3-5 euro per rail.
kr
chris
Not everything one buys transistors FOR ends up being a complete amp with housing and PSU. One often needs a source of parts that you DIDN’T pay full price for. Things you try once. Times when it just isn’t critical. Experiments That May End Badly (due credit to @Tubelab_com for that original one). He uses “dollar list” tubes. No, you can’t use outright fakes with the 2 sq. mm die and white goop, but using up your good stock might not always make sense. I keep A and B stock, and re-stock or add to the B when I get a deal. I screen all of it. They are in separate cabinets.
Thank you all, for these comments. Any interest I have in them is for replacement in amps I'd be repairing, and since these are no longer produced, if the price was right and they were not known to be fake, I had the same thought to ask for samples so I could put them on my Tektronix 577 to test.
Since I've never seen Sumitomo devices before, I was already suspect; add to that the same thought I had as @Mooly that the lettering doesn't look quite right.
With current production parts, I always buy from the big houses, but with out of production parts, having a supply for working on some of the vintage amps I've been fixing would be useful, and they are sometimes only available outside of those sources.
I'll start with asking for samples to test on the curve tracer, maybe cut one open, and take it from there. Thank you all!
Since I've never seen Sumitomo devices before, I was already suspect; add to that the same thought I had as @Mooly that the lettering doesn't look quite right.
With current production parts, I always buy from the big houses, but with out of production parts, having a supply for working on some of the vintage amps I've been fixing would be useful, and they are sometimes only available outside of those sources.
I'll start with asking for samples to test on the curve tracer, maybe cut one open, and take it from there. Thank you all!
Are there any reliable sellers on Aliexpress for power transistors? I'm quite aware of the situation but I'm just curious about how many reputable component sellers are there based on diyaudio members experiences..
You've got to ask yourself what all the labour and checking is worth. Also the cost of device failure since it only takes one bad device to take out an entire output section.
I buy current devices from authorized distributors. If you are shipping the work out with you name on it, there is no decision here. Current, new parts from known distributors.
I buy current devices from authorized distributors. If you are shipping the work out with you name on it, there is no decision here. Current, new parts from known distributors.
Yes, that has to be part of the calculation, thanks, Chris. The only reason I have entertained the idea is I know the company these came from, but I don't know if they were actually used, or tested and rejected, etc. Since the parts are NLA, if they were real, it could be an opportunity. I suppose a safer alternative would be to move towards the replacements - C5200/A1943.
Never ending undying indestructible truth.
Go for it on side projects and tinkering and experiments.
Never put that stuff in a 'Build'.
When you hear/see those words, you know you are in doo doo.
When the masters say such things, it is time to back off and take stock of what is what.
This is a classic example of why this site is a treasure.
You can retrofit almost any historical unit with modern devices. There are many exceptions , of course.
If you can measure and analyze distortion prior to retrofit, then you can measure after to compare.
Changing caps and transistors in classic gear willy nilly is a silly game.
Do it with driven purpose and scientific methods.