Diode identification?
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From: John E. on 2 Mar 2007 11:49 It's shorted, burned on the side against the board, the side of the diode that has part of the p/n printed (of course)... Best I can make out is (reading around the diode: ITT 4? 47 Physically it resembles a typical 1A black epoxy rectifier. Would this be 1n4147? The "47" is clearly visible, and I think I can make out a "4" in the first part of the poorly-legible digits. No telling how many digits between the two "4"s. Any possibilities other than 4147? Thanks, -- John English
From: Palindrome on 2 Mar 2007 12:06 John E. wrote: > It's shorted, burned on the side against the board, the side of the diode > that has part of the p/n printed (of course)... > > Best I can make out is (reading around the diode: > ITT > 4? > 47 > > Physically it resembles a typical 1A black epoxy rectifier. > > Would this be 1n4147? The "47" is clearly visible, and I think I can make out > a "4" in the first part of the poorly-legible digits. No telling how many > digits between the two "4"s. > > Any possibilities other than 4147? > Not wishing to trach granny, but this would be my approach: Reverse engineer parts of the associated circuitry until I am reasonably confident of what sort of application it is being used for, eg lf rectifier, hs switch, flywheel, etc. Or more importantly, if it is a zener.. It is normally not to difficult to work out what the diode is doing and what sort of currents, voltages and frequencies are happening to it. At that point, wire in an external diode with a much, much higher spec than the original - and measure the actual running parameters. I keep a few huge and very expensive semiconductors just for this. Then match a diode to that requirement, by measuring what is actually happening - with any luck the spec will match to something with a lot of 4s and the odd 7 in its product name. Assumptions about what things may be tend to bite.. -- Sue
From: Genome on 2 Mar 2007 12:09 "John E." <incognito(a)yahoo.com> wrote in message news:0001HW.C20D962501E3C308F01826C8(a)news.sf.sbcglobal.net... > It's shorted, burned on the side against the board, the side of the diode > that has part of the p/n printed (of course)... > > Best I can make out is (reading around the diode: > ITT > 4? > 47 > > Physically it resembles a typical 1A black epoxy rectifier. > > Would this be 1n4147? The "47" is clearly visible, and I think I can make > out > a "4" in the first part of the poorly-legible digits. No telling how many > digits between the two "4"s. > > Any possibilities other than 4147? > > Thanks, > -- > John English > Unfortunately a 1N4147 is a small signal glass diode....... I would take a guess that what you have got is a zener diode. Try googling for a 1N4747. If it's fucked then something else might have fucked it so check the rest of the circuit. However it sounds like it might have been slowly fucked so you might want to re-design the circuit. DNA
From: John E. on 2 Mar 2007 16:36 Ben Miller sez: > You can't just guess at this. As sue suggested, you need to look at the > circuitry and figure out what that diode function is. ... OK, here goes: German-made paper-handling machine, c. 1989. Circuit activates solenoid, taking several inputs from other sensors, signals, etc. Anode of unknown diode is to ground, cathode to drain of BUZ72 MOSFET. 1uF cap also from drain to ground. Drain connects to solenoid. Drive voltage is 42vdc. Thanks, -- John English
From: Arfa Daily on 2 Mar 2007 17:01
"John E." <incognito(a)yahoo.com> wrote in message news:0001HW.C20DD98F01F38FF6F01826C8(a)news.sf.sbcglobal.net... > Ben Miller sez: > >> You can't just guess at this. As sue suggested, you need to look at the >> circuitry and figure out what that diode function is. ... > > OK, here goes: > German-made paper-handling machine, c. 1989. Circuit activates solenoid, > taking several inputs from other sensors, signals, etc. > > Anode of unknown diode is to ground, cathode to drain of BUZ72 MOSFET. 1uF > cap also from drain to ground. Drain connects to solenoid. Drive voltage > is > 42vdc. > > Thanks, > -- > John English > Not then, I would suggest, a 4.7v zener ... Sounds like it's just a flywheeling diode and a 1N4007 would do the job just fine. Does the FET source go to ground ? Many power MOSFETS have a diode internally in that orientation across from the source to the drain. It gets there as an integral side effect of the manufacturing process. Arfa |