Beta Group (Hfe) of replacement transistors

Sep 20, 2005 1 Replies
T

I'm replacing a pair of shorted outputs in an Onkyo TX-SV525 AV Receiver. The manual states, "Replacements must be from the same beta group (Hfe) as the original type". This has something to do with the devices' gain, I suppose. The originals are marked "Toshiba B1557 O 5H" and "Toshiba D2386 O 5G". MCM Electronics has 2SB1557 and they sub



2SD2386 to 2SD2387. Assuming I properly replace all the other faulty components in the failed channel's output stage, what's likely to happen when I power this unit up with sub's that most likely have different Hfe than the originals? Thanks for any thoughts.
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E

As long as you "caught" all the other likely faults and faulty components like shorted diodes, open low ohm resistors, electrolytics, driver transistors, cracked solder connections, etc, etc,.. then your Onkyo amp will power up just fine even with transistors that are not exactly beta matched.... the final product might be distortion numbers that are very slightly off spec but not really a big problem. Put in the transistors that you have, doublecheck for other related failures and cross your fingers and power it up, if they blow again, it is NOT the output transistors that you installed, it would mean that you missed something. .... otherwise, enjoy the music. electricitym . .

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