[time-nuts] HP5328A LEDS driver transistor
stake at btinternet.com
Sun Jan 22 18:31:01 EST 2012
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!
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] 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
> On Sun, Jan 22, 2012 at 1:07 PM, Stan Searing <timenutstan at gmail.com>
> > 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-
> > or 497-4829-5-ND<http://search.digikey.com/us/en/products/2SB772/497-
> > from
> > DigiKey (but as mentioned by others,
> > watch the pinout, as most any power tab transistor will have the
> > 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 <djl at montana.com> 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.
> >> > 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-
> >> > 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
> >> > 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
> >> >
> >> > _______________________________________________
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> >> --
> >> "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
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> Chris Albertson
> Redondo Beach, California
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