16 Jun
2013
16 Jun
'13
7:18 p.m.
Hi all,
The LA-120 Decwriter that I got off Craigslist a couple of weeks ago has a dead H7150
power supply. Transistors Q1 and Q2 are open and shorted, respectively, and fusible
resistor R4 is open. I'd guess that failure of Q2 led to the other two parts going.
Q1 and Q2 are high voltage NPN power transistors in TO-3 cans, labeled
__
81 [ti logo] 41 (or maybe 4I but I'm guessing for a date code, 41)
R3004
BRITAIN
DEC part number appears to be 15-12782-00. The printset identifies them as "NPN 100W
S1325 15". I can't find any substitution info online. There is a NOS pair for
sale on eBay. So that's one option. Does anyone know what the modern equivalent(s)
are? And what if you do, where did you find the reference?
Thanks,
Brian
17 Jun
17 Jun
7:48 a.m.
Brian Knittel <bknittel at quarterbyte.com> writes:
The printset identifies them as "NPN 100W S1325
15".
Given that the previous three lines are:
XA 55 PNP 500MW SI 60 50 P
D 44Q5 NPN 31W SI225 30
XA 05 NPN 500MW SI 60 50 P
I'd assume that's actually meant to be
NPN 100W SI325 15
(although it looks like a 1 to me on the printset as well, Vceo = 1325V
seems a bit unlikely).
There was a thread about interpreting these specs last year:
http://www.classiccmp.org/pipermail/cctalk/2012-April/127683.html
So I guess you're looking for a silicon NPN transistor with 100W max
power dissipation, a Vceo of 325V or better, and an hFE about 15 (and
the right pinout!). Tony or one of the other PSU gurus can probably
suggest something that'll do the job?
Thanks,
--
Adam Sampson <ats at offog.org> <http://offog.org/>
2:47 p.m.
Hi all,
__
81 [ti logo] 41 (or maybe 4I but I'm guessing for a date code, 41)
R3004
BRITAIN
DEC part number appears to be 15-12782-00. The printset identifies
them as "NPN 100W S1325 15". I can't find any substitution info online.
To save you a wasted search, neither R3004 nor S1325 are listed in
'Towers International Transistor Selector' -- a book that gives brief
chracteristics of many thousands of transistors. So they must be pretty
unusual.
There is a NOS pair for sale on eBay. So that's
one option. Does anyone
know what the modern equivalent(s) are? And what if you do, where did
you find the reference? >
I've not looked at the printset, what are these transistors used for?
SMPSU chopper? I wonder if you can make sensible guesses as to the
requirements nad pick a more common transistor that will work. But if it
is a chopper, you can get grey heair trying to find one that will work.
My bitter eperience is that if you find a transisttor with simiular
published specifications to the failed chopper it may not work. There are
plenty of other chracteristcs that matter...
-tony
5:36 p.m.
On 17/06/2013 19:47, Tony Duell wrote:
Brian Knittel <bknittel at quarterbyte.com>
wrote:
> DEC part number appears to be 15-12782-00. The printset identifies
> them as "NPN 100W S1325 15". I can't find any substitution info online.
To save you a wasted search, neither R3004 nor S1325
are listed in
'Towers International Transistor Selector' -- a book that gives brief
chracteristics of many thousands of transistors. So they must be pretty
unusual.
DEC's internal parts list says 15-12782-00 is a BUY69A.
So "NPN 100W SI 325 15" makes sense (from Towers):
NPN silicon TO3 Vcb:1kV Icmax:10A Ptot:100W HFE:15(min)
--
Pete Peter Turnbull
Network Manager
University of York
4087
days inactive
4088
days old
3 comments
4 participants
participants (4)
-
ard＠p850ug1.demon.co.uk -
ats＠offog.org -
bknittel＠quarterbyte.com -
pete＠dunnington.plus.com