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Old 10th January 2011, 06:27 PM   #1
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Default Oldies from japan:) Substitutes needed for 2sa763

Hello
Iam having some problem with old transistors in a 900+ Harman Kardon 4ch reciever. The transistors needed for th tonecontrolboard is a PNP transistor 2SA763WL and I cant find them only "SA763 Y. Iam not sure what the diffrences there are. Only max voltage? I tried a substitute "SA1015 but it wont work. The sound gets very noisy and low. Any one who have a suggestion or a company that sells and distribute to Europe, Sweden.
Private person. I tried utsource and mcm but nope.
Please come with a suggestion
Best Regards from Ulf in Sweden
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Old 10th January 2011, 07:28 PM   #2
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It is strange, that your replacement didn't work. The original transistor is not that special, especially in the tone control stage. The datasheet is attached.
Was pinout the issue?
See the difference between Y, W, L, and then there are a few gain grades.
Attached Files
File Type: pdf 2SA763.pdf (84.0 KB, 19 views)
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Old 10th January 2011, 08:25 PM   #3
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Hi and thanks. I think I saw that sheet on alldatasheet

Yes its very strange it didnt work. Pinout was the same for the replacement. The chanel just sounded very weak and noisy. At the moment I decided to rbuild the tone control board with new capacitors, resistors and so on. leaving only left front chanel with new lytic capacitors. Then I see what happens. Reason why was that I suspected problems with the board itself. Spanning when it was mounted. I tested to leave the incoming leads open and changing every incoming signal to the tonecontrol and that works. Also all 4 power amplifier works and the inverterboard and the clampboard. So Iam extremly frustrated. Not a specialist on measuring different voltages on amplifiers.
This is the servicemanual
http://jbmanuals.free.fr/HarmanKardo...K900+%20sm.pdf
If u have any idea why it does this I will appreiciate any help
The tc-board only got one input voltage and these are the same for all channels.I also changed all main lytics to new ones everywhere.
So at the moment only left front works and a noisy Left back and no components on right channels.
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