Yes its tech
Yes its technically working now but is definately hotter than the same transistors on other side. They are not super hot like they were-they are touchable now but the other side is only warm. Thinking running super hot for awhile might have degraded them and although as BSST suggested it may not be the issue I would just like to take them out of the equation because if they did fail it might be catastrophic. I had looked at 2sa1837/2sc4793 before but didnt choose due to lower collector current. The 2sa1668/2sc4382 seem to meet the specs better I think so may give them a try. Thanks for the suggestions and pdfs.Why would you change 2SA1306/2SC3298 if they're working OK ?
Edit: btw, the only substitutes I came across are 2SA1837/2SC4793 still manufactured by UTC. There is also 2SA1668/2SC4382 manufactured by SanKen.
https://www.profusionplc.com/type/transistor
My rails are closer to 79v. Mabye due to slightly higher line voltage.Supply rails are about +/- 74V, or about 148V total. All other specs being similar, 180V should be ok, but of course with less margin.
Good luck!
If you want to try 2SA1668/2SC4382 be sure to buy them from a reliable source. I see a lot of fake c*ap on the internetz. Some of them are hilarious, with Toshiba logo for example ! 
This is the place where I buy them. Unfortunately there are some stock shortages recently.
https://www.tme.eu/en/details/2sa1668/pnp-tht-transistors/sanken/
Edit: 2SC3298/2SA1306 were among the best drivers. I don't see a direct replacement. Maybe someone could give a better suggestion btw.

This is the place where I buy them. Unfortunately there are some stock shortages recently.
https://www.tme.eu/en/details/2sa1668/pnp-tht-transistors/sanken/
Edit: 2SC3298/2SA1306 were among the best drivers. I don't see a direct replacement. Maybe someone could give a better suggestion btw.
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+/- 80V rails is about 160V rail-to-rail, so you've still got 20V margin against the 180V red line of those substitute transistors. 😉
I think it's wise to have the new transistors in reserve for repair, but if heat is the issue, I recommend taking voltage measurements across all those emitter resistors, both in the problem channel and the "good" channel for reference. I recommend tabulating in a spreadsheet and believe the side-by-side data might be insightful.
I think it's wise to have the new transistors in reserve for repair, but if heat is the issue, I recommend taking voltage measurements across all those emitter resistors, both in the problem channel and the "good" channel for reference. I recommend tabulating in a spreadsheet and believe the side-by-side data might be insightful.
Edit: I would rather use 2SA1837/2SC4793 instead of 2SA1668/2SC4382. They are much closer to 2SC3298/2SA1306. As a matter of fact, I wouldn't use 2SA1668/2SC4382 at all !
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*bump
Do what BSST suggested first. Btw, when you pulled out the original 2SA1306/2SC3298, did you do a quick diode test between the leads ? Heck, don't say you didn't ! gto127 you're not helping us. This will end up in a disaster mate. You were already close to it. Probably the Almighty gave you a second chance ! 😉 🙂
/me... from now on, I'll just sit in the corner and watch this thread... 😉
Do what BSST suggested first. Btw, when you pulled out the original 2SA1306/2SC3298, did you do a quick diode test between the leads ? Heck, don't say you didn't ! gto127 you're not helping us. This will end up in a disaster mate. You were already close to it. Probably the Almighty gave you a second chance ! 😉 🙂
/me... from now on, I'll just sit in the corner and watch this thread... 😉
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I did do a diode test- must have been breaking down under higher voltage.*bump
Do what BSST suggested first. Btw, when you pulled out the original 2SA1306/2SC3298, did you do a quick diode test between the leads ? Heck, don't say you didn't ! gto127 you're not helping us. This will end up in a disaster mate. You were already close to it. Probably the Almighty gave you a second chance ! 😉 🙂
/me... from now on, I'll just sit in the corner and watch this thread... 😉
The originals have 1.5 amp collector current capability these have only 1. Does that not matter in this application?Edit: I would rather use 2SA1837/2SC4793 instead of 2SA1668/2SC4382. They are much closer to 2SC3298/2SA1306. As a matter of fact, I wouldn't use 2SA1668/2SC4382 at all !
Do you happen to know if these transistors need to be matched? I can see due to scarcity finding matched ones would be hard to do.+/- 80V rails is about 160V rail-to-rail, so you've still got 20V margin against the 180V red line of those substitute transistors. 😉
I think it's wise to have the new transistors in reserve for repair, but if heat is the issue, I recommend taking voltage measurements across all those emitter resistors, both in the problem channel and the "good" channel for reference. I recommend tabulating in a spreadsheet and believe the side-by-side data might be insightful.
Thats good news. In case I have to go with subs do you think they would draw over an amp collector current?(thats what sub is rated for)Because of all the emitter resistors, I believe matching should not be necessary.
As I read data, max DC collector current is 2A on your new transistors, vs. only 1.5 on the original. I think you may have focused on max base current rather the collector current which is more pertinent.
It’s not so much the actual max rating that’s important, but if the beta holds out and stays flat to a high enough current. This is far more critical in the driver transistor than the outputs.
2SA1930 2SC5171 are more capable than the other toshibas suggested here.
I scavenged some from a dead onkyo receiver.
edit: https://www.mouser.com/datasheet/2/408/7654-58852.pdf
I scavenged some from a dead onkyo receiver.
edit: https://www.mouser.com/datasheet/2/408/7654-58852.pdf
OK I could thought it said 1 amp. I must have been looking at spec sheet wrong . Thanks for looking up.As I read data, max DC collector current is 2A on your new transistors, vs. only 1.5 on the original. I think you may have focused on max base current rather the collector current which is more pertinent.
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