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| Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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Sumitomo Transistors any good?
Hi all, Can anyone please help me? I am working on a Crest 1400 power amp. I replaced all 6 pairs of b600/d555 outputs (1 chan). The amp played fine for 10 minutes at low volume then I cranked it up (scope showed music appx 60vpp into 4 ohms) then the same channel blew again. this time the pair of 2sa1006/2sc2336 (to220's) shorted too but the drivers 2sa1302/2sc2381 were still good. All other parts seem ok too. I used Sumitomo brand transistors not NEC. So the question is... Can anyone say good or bad about that brand? Or was there something else that I missed? Where can I get good INEXPENSIVE substitutes or must I use only the NEC's? Where can I get the NEC's cheap? the NEC's at MCM is about $8 times 12 pcs plus tax plus shipping!! Thanks a million in advance... baffled and disappointed |
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#3
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I find what you say verry intresting.
Can you please tell me where I can read more about fake transistors and Japanese numbering system. Mr Nisse Tim Schwartz wrote: Hello, Sorry to hear of your problems. There have been lots of fake transistors out there, often marked with legitimate brands. I have no experience with Sumitomo transistors. However, as far as I know, the Japanese numbering system is such that a number is assigned to one brand only. For example, a 2SA1302 is a Toshiba number, and no one else will make it. If Sony wanted to make a device with the same specs, it would still be assigned a new number. So, if the original transistors were NEC, anything with the same number, but NOT NEC is suspect. Regards, Tim Schwartz Bristol Electronics wrote: Hi all, Can anyone please help me? I am working on a Crest 1400 power amp. I replaced all 6 pairs of b600/d555 outputs (1 chan). The amp played fine for 10 minutes at low volume then I cranked it up (scope showed music appx 60vpp into 4 ohms) then the same channel blew again. this time the pair of 2sa1006/2sc2336 (to220's) shorted too but the drivers 2sa1302/2sc2381 were still good. All other parts seem ok too. I used Sumitomo brand transistors not NEC. So the question is... Can anyone say good or bad about that brand? Or was there something else that I missed? Where can I get good INEXPENSIVE substitutes or must I use only the NEC's? Where can I get the NEC's cheap? the NEC's at MCM is about $8 times 12 pcs plus tax plus shipping!! Thanks a million in advance... baffled and disappointed |
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#4
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Hello,
The info on fake transistors was posted here in one of these news groups in the last year or so. I did not save theatricals, but a search should turn it up. My understanding on the Japanese numbering system come from headers in Japanese transistor data books I have. I've never checked with the industry association. Regards, Tim Schwartz Bristol Electronics "klasspappa[remove]" wrote: I find what you say verry intresting. Can you please tell me where I can read more about fake transistors and Japanese numbering system. Mr Nisse Tim Schwartz wrote: Hello, Sorry to hear of your problems. There have been lots of fake transistors out there, often marked with legitimate brands. I have no experience with Sumitomo transistors. However, as far as I know, the Japanese numbering system is such that a number is assigned to one brand only. For example, a 2SA1302 is a Toshiba number, and no one else will make it. If Sony wanted to make a device with the same specs, it would still be assigned a new number. So, if the original transistors were NEC, anything with the same number, but NOT NEC is suspect. Regards, Tim Schwartz Bristol Electronics wrote: Hi all, Can anyone please help me? I am working on a Crest 1400 power amp. I replaced all 6 pairs of b600/d555 outputs (1 chan). The amp played fine for 10 minutes at low volume then I cranked it up (scope showed music appx 60vpp into 4 ohms) then the same channel blew again. this time the pair of 2sa1006/2sc2336 (to220's) shorted too but the drivers 2sa1302/2sc2381 were still good. All other parts seem ok too. I used Sumitomo brand transistors not NEC. So the question is... Can anyone say good or bad about that brand? Or was there something else that I missed? Where can I get good INEXPENSIVE substitutes or must I use only the NEC's? Where can I get the NEC's cheap? the NEC's at MCM is about $8 times 12 pcs plus tax plus shipping!! Thanks a million in advance... baffled and disappointed |
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#5
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Tim Schwartz wrote:
Hello, The info on fake transistors was posted here in one of these news groups in the last year or so. I did not save theatricals, but a search should turn it up. My understanding on the Japanese numbering system come from headers in Japanese transistor data books I have. I've never checked with the industry association. Regards, Tim Schwartz Bristol Electronics You can try: http://transfal.tripod.com/ It's a page in spanish, but with lots of pictures of counterfeit transistors. --- El Meda. http://ingemeda.tripod.com/ |
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