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Old 30th January 2004, 04:12 PM   #1
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Join Date: Jan 2004
Location: Leeds, West Yorkshire
Default 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
- 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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Old 30th January 2004, 06:50 PM   #2
Did it Himself
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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.
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Old 30th January 2004, 09:30 PM   #3
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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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