PNP NPN Complimentary Transistors

dannywhac · 12th August 2009, 07:16 PM

Hi - I'm repairing my old Sony F110 amp at the moment (see the end of this thread) and have discovered it's the output transistors causing the fuse blow.

After some searching (and help from Sinistersoulz) for replacement transistors 2SA1670 and 2SC4385, I've discovered the 4385's are near on impossible to source (unless I fancy paying a fair amount of postage from the States).

Cricklewood Electronics have recommended replacing the transistors with a different complimentary pair - 2SC4388 and 2SA1673. Having had a butchers at the datasheets they seem comparable to the original transistors, although I'm a bit reluctant to bung 'em in until I've had a bit more confirmation as I'd rather not fry anything else in my beloved amp!

What do you think? And ta in advance!

richie00boy · 12th August 2009, 07:21 PM

Replace the drivers as well or you will probably end up doing it all over again.

h_a · 20th August 2009, 06:23 AM

I just had a short look at the datasheets and the Sanken 2SC4388 seems a good replacement to me. Similar fT and available in the same hfe-groups. Higher Voltage ratings may indicate higher capacitances as well, but that's most certainly not much of an issue.

Just be sure to check the hfe-group (O,P or Y) on the original (destroyed) parts and order the replacments from the same group. If in doubt go for the Y parts with highest hfe.

I would replace drivers as well to be sure (or at least test them) as richie already recommended.

Have fun, Hannes

12th August 2009, 07:16 PM	#1
dannywhac diyAudio Member Join Date: Aug 2009	PNP NPN Complimentary Transistors Hi - I'm repairing my old Sony F110 amp at the moment (see the end of this thread) and have discovered it's the output transistors causing the fuse blow. After some searching (and help from Sinistersoulz) for replacement transistors 2SA1670 and 2SC4385, I've discovered the 4385's are near on impossible to source (unless I fancy paying a fair amount of postage from the States). Cricklewood Electronics have recommended replacing the transistors with a different complimentary pair - 2SC4388 and 2SA1673. Having had a butchers at the datasheets they seem comparable to the original transistors, although I'm a bit reluctant to bung 'em in until I've had a bit more confirmation as I'd rather not fry anything else in my beloved amp! What do you think? And ta in advance!

12th August 2009, 07:21 PM	#2
richie00boy Did it Himself diyAudio Member Join Date: Nov 2003 Location: Gloucestershire, England, UK	Replace the drivers as well or you will probably end up doing it all over again. __________________ www.readresearch.co.uk my website for UK diy audio people - designs, PCBs, kits and more

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20th August 2009, 06:23 AM	#3
h_a diyAudio Member Join Date: Sep 2006 Location: Graz, Austria	I just had a short look at the datasheets and the Sanken 2SC4388 seems a good replacement to me. Similar fT and available in the same hfe-groups. Higher Voltage ratings may indicate higher capacitances as well, but that's most certainly not much of an issue. Just be sure to check the hfe-group (O,P or Y) on the original (destroyed) parts and order the replacments from the same group. If in doubt go for the Y parts with highest hfe. I would replace drivers as well to be sure (or at least test them) as richie already recommended. Have fun, Hannes