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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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Simple transistor circuit sub help needed
Hi, folks:
I'd like to tap you folks' knowledge, for this is not something I do every day. I have a failed uPA1478H (four element silicon transistor array), but only one-fourth of it is bad I am repairing a Subaru ECM, that presently does not provide a ground for the Check Engine Light (CEL). I have determined that the base drive is present, but the failed junction does not turn on to complete the lamp ground. As I don't see an easy source for a replacement uPA1478 (tell me if you find one), what I'd like to do is sub a discrete transistor for that element, preferably one I already have in my junk bin -- I have a pretty decent junk bin. Datasheet picture (PNG format, with my scribbled-in circuit notes) he http://www.ncplus.net/~asavage/Subaru/uPA1478_01_.png (77k) http://www.ncplus.net/~asavage/Subaru/uPA1478_02.png (37k) Or, if you prefer JPEGs: http://www.ncplus.net/~asavage/Subaru/uPA1478_01_.jpg (147k) http://www.ncplus.net/~asavage/Subaru/uPA1478_02.jpg (74k) (Original NEC datasheet: http://www.necel.com/nesdis/image/IC-3566.pdf (59k) ) As you can see, the purpose is for 5v at the base (pin 8) to complete the lamp's ground (connect pin 9 collector to pin 10 emitter/ground) -- this is the OEM circuit. I don't think that I need the zener included in the original design, there's no inductive load. I do not know how much base drive current I have available beyond what the uPA1478 requires. Suggestions? -- Regards, Al S. |
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Simple transistor circuit sub help needed
On Mon, 8 Sep 2003 02:22:07 UTC, "Al Savage" wrote:
Find the specs at http://www.nteinc.com/specs/2300to2399/pdf/nte2338.pdf A cursory look through my junk bin yielded two D2018 parts, which cross to NTE2338, so I'm all set. Soldered in, testing tomorrow. The 2SD2018 is working perfectly. Again, I thank you. -- Regards, Al S. This OS/2 system ("Tori", W4 FP15) uptime is 8 days 10:18 hours |
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