Chris, Try BC327 / BC328, they are pinout-compatible if you fit them "flipped". On paper they are less powerful but the high gain and low saturation voltage works in your favour. I have used them for anode drivers in seven segment displays. Inexpensive, worth a try! Kind regards
Chris > -----Original Message----- > From: [email protected] [mailto:[email protected]] On > Behalf Of Chris Albertson > Sent: 22 January 2012 22:41 > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] HP5328A LEDS driver transistor > > Thanks everyone for all the options. OK there are real MPS-U51 for $5 > or $6 each. The NTE parts sells for between $25 and $30. HP places > these just on top of each digit with the tap fasting the plastic LED > so it can't short. HP also cuts the taps so they can't short to the > case. I think they grossly per spec'd them because they are used in a > place where there is no heat sink and very little airflow. I say > "over spec" but yet two burn out. > > Funny the seller thought the counter worked. The burned out digits > were the least significant and with them out you still have a 7 > digital counter. Really all that most people need for aligning radios > and such. > > My plan now is to do a parametric search on Digikey/Mouser a quick > search found many for under $1 that could work. I'll wait 'till I'm > in need of some parts to build my next projects and add a few > transistors. > > > On Sun, Jan 22, 2012 at 1:07 PM, Stan Searing <[email protected]> > wrote: > > > on my shelf I'd sell for $50 if you are ever up in San Jose). > > If you could drop them at Cal State I might take you up on that. > Yes, I'll look at that transistor below > > > I'd use a MJE171GOS- > ND<http://search.digikey.com/us/en/products/MJE171G/MJE171GOS-ND/919498> > > or 497-4829-5-ND<http://search.digikey.com/us/en/products/2SB772/497- > 4829-5-ND/954133> > > from > > DigiKey (but as mentioned by others, > > watch the pinout, as most any power tab transistor will have the > collector > > in the center, > > while the MPS-U51 is one of the few exceptions). You might also need to > > slim down > > the leads to fit the PC board. > > > > Stan > > > > > > > > > > On Sun, Jan 22, 2012 at 12:34 PM, Don Latham <[email protected]> wrote: > > > >> NTE lists their equivalent as: NTE-189 See: > >> http://nte01.nteinc.com/nte/NTExRefSemiProd.nsf/$$Search > >> Newark has 262 of them :-) > >> Don > >> Chris Albertson > >> > I have an eBay HP5328A counter with two dead digits on the display. > I > >> > figured out the problem was two dead transistors. I can swap > >> > transistors with a good digit and the problem moves. > >> > > >> > I'd not worked on LED displays before. Turns out only one digit is > >> > lit up at a time, they strobe the digits in sequence. The dead > >> > transistor is the one that controls the all the anodes in the > >> > 7-segment LED module. The service manual describes the transistor > >> > like this: "part number = 1853-0326", "description = TRANSISTOR PNP > >> > SI ... FT-50MHZ" > >> > The p/n 1853-0326 cross references to a Motorola MPS-U51. The MPS- > U51 > >> > data sheet matches the part that fails so I'm sure I got a correct > >> > cross ref. > >> > I took a photo of the dead transistor. It is on .1" perf board for > >> > scale. You can read the "3-326" p/n and see the Motorola "M" logo. > >> > http://www.dropbox.com/gallery/28915695/1/HP5328A?h=da35c1 > >> > > >> > I look up the spec in the mps-u51 and see it is a to-220 like case > and > >> > can handle 1W. I'm really surprised it burned out as I doubt an LED > >> > requires 1W even if showing an "8". Reading the mps-u51 spec sheet I > >> > see it has a low saturation voltage. Maybe that is why the selected > >> > it as it is being driven by 7400 TTL logic that goes through a > >> > connector and has some resistors involved. > >> > > >> > Question: These seem to be hardtop find. Can anyone suggest a good > >> > sub" > >> > > >> > > >> > > >> > Thanks, > >> > Chris Albertson > >> > Redondo Beach, California > >> > > >> > _______________________________________________ > >> > time-nuts mailing list -- [email protected] > >> > To unsubscribe, go to > >> > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > >> > and follow the instructions there. > >> > > >> > >> > >> -- > >> "Neither the voice of authority nor the weight of reason and argument > >> are as significant as experiment, for thence comes quiet to the mind." > >> R. Bacon > >> "If you don't know what it is, don't poke it." > >> Ghost in the Shell > >> > >> > >> Dr. Don Latham AJ7LL > >> Six Mile Systems LLP > >> 17850 Six Mile Road > >> POB 134 > >> Huson, MT, 59846 > >> VOX 406-626-4304 > >> www.lightningforensics.com > >> www.sixmilesystems.com > >> > >> > >> > >> _______________________________________________ > >> time-nuts mailing list -- [email protected] > >> To unsubscribe, go to > >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > >> and follow the instructions there. > >> > > _______________________________________________ > > time-nuts mailing list -- [email protected] > > To unsubscribe, go to https://www.febo.com/cgi- > bin/mailman/listinfo/time-nuts > > and follow the instructions there. > > > > -- > > Chris Albertson > Redondo Beach, California > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time- > nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
