Unfindable driving transistor

Frisbee78 · 30th January 2004, 04:12 PM

Hi everybody!

I am attempting the repair of my mate's amp but I am stuck to find a replacement for the driving transistor, called B647A. After some Googling around, I found that these where only available in Japan... Great, I live in England

So, does anyone know either:
- where I could find a B647A in the cupatea country
or
- what substitute to the B647A I may use (if I must)

Also, if you could take a look at the pics here and here, showing the extent of the damages as I can see them, could you let me know if there is anything I might have missed out? Thanks a lot in advance.

Oh and by the way, the amp is (was?) a Denon AVC-1530.

Thanks all

richie00boy · 30th January 2004, 06:50 PM

The power transistor is made by Sanken if that's any help.

The B647A is actually 2SB647A and is PNP, but I guess you knew that.

I am only going by what transistors I have used myself in similar applications and that 'stretched' TO92 driver transistor is like ones I use for drivers, so it could well be a suitable replacement. They are made by Sanyo and are 2SC2910 (NPN) and 2SA1208 (PNP). However, I wouldn't like to use these for more than a 60W/8R amp. If it's much more than this you could try MJE15032/33 or MJE340/350.

You may also like to try Toshiba 2SC5200 (NPN) and 2SA1943 (PNP) power devices as replacements.

You can get these parts from Profusion who are a UK company are very nice to deal with. They also sell Sanken transistors so may have original replacements anyway.

What camera do you use? I like how your pics have come out and need a similar capability myself.

Frisbee78 · 30th January 2004, 09:30 PM

Thanks for your reply richie00boy.

I hadn't realised that B647A stood for 2SB647A. Duh!

The 2SA1491 had its full ref given away as it was written on the PCB...

I forgot to mention that I already found a replacement for the 2SA1491 which I got from a company called Telepart.
I just realised that they also have the 2SA647A in their list.
If I had known, I would have ordered them together, saving me having to pay for the P&P twice. Oh well...

Thanks also about the replacement alternatives you offered for the 2SA647A. If I can't get hold of one, I'll consider your propositions.

About my camera, I used the Canon PowerShot S50 (retails at a bit over £300). A very good review is available here. Note that the images I posted have been reduced to 1024x768 from their orginial resolution of 2592x1944. That extra resolution was useful for the zoom on the 2SA647A.

30th January 2004, 04:12 PM	#1
Frisbee78 diyAudio Member Join Date: Jan 2004 Location: Leeds, West Yorkshire	Unfindable driving transistor Hi everybody! I am attempting the repair of my mate's amp but I am stuck to find a replacement for the driving transistor, called B647A. After some Googling around, I found that these where only available in Japan... Great, I live in England So, does anyone know either: - where I could find a B647A in the cupatea country or - what substitute to the B647A I may use (if I must) Also, if you could take a look at the pics here and here, showing the extent of the damages as I can see them, could you let me know if there is anything I might have missed out? Thanks a lot in advance. Oh and by the way, the amp is (was?) a Denon AVC-1530. Thanks all

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30th January 2004, 06:50 PM	#2
richie00boy Did it Himself diyAudio Member Join Date: Nov 2003 Location: Gloucestershire, England, UK	The power transistor is made by Sanken if that's any help. The B647A is actually 2SB647A and is PNP, but I guess you knew that. I am only going by what transistors I have used myself in similar applications and that 'stretched' TO92 driver transistor is like ones I use for drivers, so it could well be a suitable replacement. They are made by Sanyo and are 2SC2910 (NPN) and 2SA1208 (PNP). However, I wouldn't like to use these for more than a 60W/8R amp. If it's much more than this you could try MJE15032/33 or MJE340/350. You may also like to try Toshiba 2SC5200 (NPN) and 2SA1943 (PNP) power devices as replacements. You can get these parts from Profusion who are a UK company are very nice to deal with. They also sell Sanken transistors so may have original replacements anyway. What camera do you use? I like how your pics have come out and need a similar capability myself.

30th January 2004, 09:30 PM	#3
Frisbee78 diyAudio Member Join Date: Jan 2004 Location: Leeds, West Yorkshire	Thanks for your reply richie00boy. I hadn't realised that B647A stood for 2SB647A. Duh! The 2SA1491 had its full ref given away as it was written on the PCB... I forgot to mention that I already found a replacement for the 2SA1491 which I got from a company called Telepart. I just realised that they also have the 2SA647A in their list. If I had known, I would have ordered them together, saving me having to pay for the P&P twice. Oh well... Thanks also about the replacement alternatives you offered for the 2SA647A. If I can't get hold of one, I'll consider your propositions. About my camera, I used the Canon PowerShot S50 (retails at a bit over £300). A very good review is available here. Note that the images I posted have been reduced to 1024x768 from their orginial resolution of 2592x1944. That extra resolution was useful for the zoom on the 2SA647A.

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