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Transistor dilemma.

H

Hifibythekg

Super Member
One of a pair of complementary driver transistors in a Rotel RA-913 has failed.

I have a modern replacement to hand.

The question...

Can I just fit it and it should happily work in partnership with the good original one?

OR

Do I also need to source, buy and fit the modern counterpart of the good transistor and replace the perfectly good original one?


Failed transistor:
2SC1567 (Q607)

Modern replacement:
KSC 3503 (Q605)

Complementary (good original) paired transistor:
2SA794,

Modern replacement:
KSA1381
 
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Hifibythekg said:
Can I just fit it and it should happily work in partnership with the good original one?
Click to expand...
Usually not, you need to replace both, the replacements are complementary just like the originals were, but a single (modern) replacement isn't necessary complementary with an original.
 
Thanks Hyperion.
Now, the one I have is a Mouser-supplied ON Semi KSC3503DS.
If I buy KSC3503 but maybe by a different manufacturer from another reputable parts dealer should this work perfectly well? I'm in London UK, so the big shipping costs for one transistor are incredibly discouraging..
BTW Thanks for the super speedy reply!
 
Maybe I should also add that these driver transistors will be driving 4 replaced output transistors.
One 2SC1403A had failed and I've now procured four MJ15022's.
Actually.. will the other channel also require both of the functioning original driver transistors to be replaced?
 
I see you're UK based. Please feel free to recommend (via PM if you wish) any good small quantity supplier of these parts.
 
As I'm based in the UK, I'll send you a 1381 if you like? It may have been used for testing but will be 100% as new Pm your address over.

Also maybe a good idea to just use the one thread for repairing this amp, instead of a few separate ones.
 
Thanks Guys.

Reddish, that’s very kind of you, I’ve just PM’d my address.

Point taken on the threads and, yes, Q611 and 613!

And that’s a great piece by Hopjohn, rather wish that I’d read it earlier in my journey, but thanks for recommending.
 
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