Transistor Replacement Woes

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Hello everyone,

I'm hoping you could help with a repair I'm attempting on an active sub, the board is referenced 'SUB100C'

A transistor has died on the board, model '647' (note it just says 647, not B647 etc)

It is a pair with '667'

After a quick Google I found it could is most likely a model 'B647' transistor however I am unable to find a suitable replacement to that transistor.

Does anyone have any suggested replacements which are currently in production?

I can find plenty on eBay however these are likely fakes (unless anyone in the UK can point me in the direction of quality copies?)

I have also searched on RS Online and Farnell but find no matches with identical (or even similar) specifications? (The closest match I can find has a vastly different Ft which I am lead to believe is rather important to match?)

A Datasheet can be found:

https://alltransistors.com/pdfdatasheet_update/2sb647-b.pdf

Thank you all for your help!


UPDATE:

I have been mercilessly searching all day for a suitable replacement, the closest i have been able to find based on the specs of the old B647 is the

KSA1220

Which would be paired with

KSC2690

Could anyone confirm if these would be a suitable replacement for the B647 and D667's?

DATASHEET:
https://docs.rs-online.com/ff4d/0900766b8145d625.pdf
 
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Try BC640 from farnell. Gain is a little lower, may not matter, and I bought some this spring.
BC639 is npn. farnell had those too, in US. Both worked in the organ engine I put them in. Instead of some leaky garbage the vendor had populated the replacement board with. Probably bought on ebay/ali to match an obsolete part number.
Both are BCE.
 
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You won't find original Hitachi/Renesas transistor 2SB647 or its complement 2SD667, as they have been obsolete for many years. You do find generic copies from several legitimate Chinese sources with similar part numbers and such were most likely the original parts in your subwoofer amp. Yes, the generics now are the original parts in consumer products! These types usually have simplified datasheets and similar reference numbers like H647A/H667A, SB647/SD667 etc. for easy identification.

I think you can only buy the larger TO126 size complements 2SD669/2SB649 in the UK (Profusion PLC has them). Reichelt in Germany sells the smaller TO92L or T092MOD versions like yours with reference numbers SB647/SD667 but they attach the obsolete Renesas datasheets to their listings without qualification.
SB 647: Transistor 2SB 647, Si-P, 120 V, 1 A, 0.9 W, 140 MHz at reichelt elektronik
SD 667: Transistor 2SD 667 NPN, 120 V, 1 A, TO-92MOD at reichelt elektronik

As previously posted, if you decide to use the larger types, watch the pinouts (follow the datasheets or perhaps use a component tester to identify them correctly).
 
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Hello everyone,
UPDATE:

I have been mercilessly searching all day for a suitable replacement, the closest i have been able to find based on the specs of the old B647 is the

KSA1220

Which would be paired with

KSC2690

Could anyone confirm if these would be a suitable replacement for the B647 and D667's?

DATASHEET:
https://docs.rs-online.com/ff4d/0900766b8145d625.pdf

Have you tried them? Were they a drop-in replacement or did you have to change any part of the circuit?
 
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This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.