14 Apr
2008
14 Apr
'08
1:56 p.m.
I aquired a HP 9816 with a faulty power supply.
Thanks to the diagrams of Tony I found out that the switching transistor
QP1008 is shorted and a 2n2222 but thats no problem.
I googled for it and searched my datbooks but can't find any replacement or
datasheet for it.
So does somebody knows the specs or a replacement for this transistor ?
There was also a second processorboard in it from Newport Digital with a
68020 at 33Mhz, does anybody know these boards?
Rik
14 Apr
14 Apr
2:13 p.m.
Rik wrote:
I aquired a HP 9816 with a faulty power supply.
Thanks to the diagrams of Tony I found out that the switching transistor
QP1008 is shorted and a 2n2222 but thats no problem.
I googled for it and searched my datbooks but can't find any replacement
or
datasheet for it.
So does somebody knows the specs or a replacement for this transistor ?
Maybe I don't understand what you're asking, but the replacement for a
2N2222 is a 2N2222. They're still made, and not at all hard to find.
If that's not what you're trying to replace, what is the part number
you're replacing? I could be wrong, but QP1008 looks like a component
designator, not a part number. Even if there's only an HP part number
(e.g., 181x-xxxx), that's more useful for finding a replacement than
a component designator.
Eric
2:35 p.m.
Sorry, I need to replace both and ment that the 2n2222 isn't a problem, but
the QP1008 is.
The PSU isn't build by HP but by RTE POWER/MATE a firm with doesn't exist
any more.
The text on the QP1008 (TO3) is QP1008 and the date stamp 8413 and the
Motorola sign.
I do have a Motorola component cataloge from '83 but can't find the part in
there and in my other books.
On the schematics of Tony the part is mentioned as QP1008
http://www.hpmuseum.net/document.php?hwfile=4020
I need to know witch transistor I can use to replace it.
Rik
----- Original Message -----
From: "Eric Smith" <eric at brouhaha.com>
To: "General Discussion: On-Topic and Off-Topic Posts"
<cctalk at classiccmp.org>
Sent: Monday, April 14, 2008 11:13 PM
Subject: Re: Replacement for QP1008 (HP9816 PSU)
Rik wrote:
I aquired a HP 9816 with a faulty power supply.
Thanks to the diagrams of Tony I found out that the switching transistor
QP1008 is shorted and a 2n2222 but thats no problem.
I googled for it and searched my datbooks but can't find any replacement
or
datasheet for it.
So does somebody knows the specs or a replacement for this transistor ?
Maybe I don't understand what you're asking, but the replacement for a
2N2222 is a 2N2222. They're still made, and not at all hard to find.
If that's not what you're trying to replace, what is the part number
you're replacing? I could be wrong, but QP1008 looks like a component
designator, not a part number. Even if there's only an HP part number
(e.g., 181x-xxxx), that's more useful for finding a replacement than
a component designator.
Eric
2:58 p.m.
Rik wrote:
The PSU isn't build by HP but by RTE POWER/MATE a
firm with doesn't exist
any more.
That explains it. If HP bought the PSU as an assembly, there wouldn't
be HP part numbers for its components, as it would be considered a single
FRU.
From Tony's schematic, I'd guess that it's
a semi-custom part. Motorola
probably binned one of their standard parts to a
higher spec for RTE.
Perhaps you can look at schematics for other switching PSUs
with similar ratings and determine what transistor they use. The
safety-critical parameters are breakdown voltage and maximum current.
If the PSU is rated at less than 500W, I suspect you could use a BU208A,
which costs less than $3 from Digikey, but don't take my word for it.
Eric
3:24 p.m.
Rik wrote:
Is that _always_ the case? I think I've seen a Tandon TM100 drive where
the logic board is identical in layout and circuitry to a standard one,
but is gold-plated (like most HP boards of the time), has an HP part
number in the etch and 1820-xxxx chips on it. I would be very suprised if
HP made that board themselves.
The PSU isn't build by HP but by RTE
POWER/MATE a firm with doesn't exist
any more.
That explains it. If HP bought the PSU as an assembly, there wouldn't
be HP part numbers for its components, as it would be considered a single
FRU. From Tony's schematic, I'd guess that
it's a semi-custom part. Motorola
probably binned one of their standard parts
to a higher spec for RTE.
Perhaps you can look at schematics for other switching PSUs
with similar ratings and determine what transistor they use. The
safety-critical parameters are breakdown voltage and maximum current.
Too low a current gain may mean the transistor operates in the linear
part of its chracteristic, and promptly overheats.
If the PSU is rated at less than 500W, I suspect you
could use a BU208A,
which costs less than $3 from Digikey, but don't take my word for it.
I am almost sure it's less than 500W. It's quite a small supply.
A BU208A is a good suggestion. As is a 2SC1942. And there are many
others. The problem is it gets expensive if one fials after another. And
you don't know if they're failing becuase they're unsuitable or because
the original fault, the one that caused the original transistor to fail,
is still there.
-tony
15 Apr
15 Apr
2:05 a.m.
Rik wrote:
Sorry, I need to replace both and ment that the 2n2222 isn't a problem, but
the QP1008 is.
The PSU isn't build by HP but by RTE POWER/MATE a firm with doesn't exist
any more.
The text on the QP1008 (TO3) is QP1008 and the date stamp 8413 and the
Motorola sign.
I do have a Motorola component cataloge from '83 but can't find the part in
there and in my other books.
On the schematics of Tony the part is mentioned as QP1008
http://www.hpmuseum.net/document.php?hwfile=4020
I need to know witch transistor I can use to replace it.
A line of speculation, FWIW:
1. Looking through the cross-refs of the 1984 Moto Bipolar Power Transistor and
Thyristor databook, the only part I spot with a number portion of 1008 is
UMT1008. Yes, that's a speculative and questionable association in-and-of
itself, but sometimes house or custom-request numbers bear some inheritance
from the common part number.
2. The "Motorola Similar Replacement" for UMT1008 is MJ13014.
3. Basic specs on the MJ13014:
"Switchmode Series NPN Silicon Power Transistor"
"..designed for high-voltage, high-speed, power-switching in inductive
circuits where fall-time is critical.."
"..particularly suited for switchmode applications such as: switching
regulators, inverters.. [etc]"
TO-3 package
VCEO: 350V
IC: 10A
Pd @ 25C: 150W
hfe: 12 min
60nS inductive fall time @ 25C
800nS inductive storage time @ 25C
Perhaps Moto was asked to supply something that
looked-like/similar-to/spec'ed-version-of a UMT1008.
The basic specs would suggest it passes a sniff test, but I'm not familiar with
the actual power supply so I'll leave it to others to perhaps comment on
applicability in the specific.
1:43 a.m.
Based on the specs placed on the board 5V/6A +14/1.6A -14/0.5A and a assumed
~80% efficiency, simple power calculation give (30W + 22,4W + 7W)/0.8 =
74,25 say 75-80W.
So I think I'll use one of the supposed replacements.
Rik
----- Original Message -----
From: "Brent Hilpert" <hilpert at cs.ubc.ca>
To: <General at priv-edtnaa03.telusplanet.net>;
"Discussion at priv-edtnaa03.telusplanet.net :On-Topic and Off-Topic Posts"
<cctalk at classiccmp.org>
Sent: Tuesday, April 15, 2008 11:05 AM
Subject: Re: Replacement for QP1008 (HP9816 PSU)
Rik wrote:
Sorry, I need to replace both and ment that the 2n2222 isn't a problem,
but
the QP1008 is.
The PSU isn't build by HP but by RTE POWER/MATE a firm with doesn't exist
any more.
The text on the QP1008 (TO3) is QP1008 and the date stamp 8413 and the
Motorola sign.
I do have a Motorola component cataloge from '83 but can't find the part
in
there and in my other books.
On the schematics of Tony the part is mentioned as QP1008
http://www.hpmuseum.net/document.php?hwfile=4020
I need to know witch transistor I can use to replace it.
A line of speculation, FWIW:
1. Looking through the cross-refs of the 1984 Moto Bipolar Power
Transistor and
Thyristor databook, the only part I spot with a number portion of 1008 is
UMT1008. Yes, that's a speculative and questionable association in-and-of
itself, but sometimes house or custom-request numbers bear some
inheritance
from the common part number.
2. The "Motorola Similar Replacement" for UMT1008 is MJ13014.
3. Basic specs on the MJ13014:
"Switchmode Series NPN Silicon Power Transistor"
"..designed for high-voltage, high-speed, power-switching in inductive
circuits where fall-time is critical.."
"..particularly suited for switchmode applications such as: switching
regulators, inverters.. [etc]"
TO-3 package
VCEO: 350V
IC: 10A
Pd @ 25C: 150W
hfe: 12 min
60nS inductive fall time @ 25C
800nS inductive storage time @ 25C
Perhaps Moto was asked to supply something that
looked-like/similar-to/spec'ed-version-of a UMT1008.
The basic specs would suggest it passes a sniff test, but I'm not familiar
with
the actual power supply so I'll leave it to others to perhaps comment on
applicability in the specific.
14 Apr
14 Apr
3:18 p.m.
Rik wrote:
Err, no....
This PSU [1] has 2 transistors on the primary side. The chopper,
component reference Q2, is a TO3 can marked 'QP1008'. There's also a
current-sense transistor, Q1, a 2N2222
The latter is not a problem to replace. The 2N2222 is trivial to find,
and it's not _that__ critical anyway. But the chopper transistor is
almost certainly selected for some parameter, but I have no idea what (so
that, for example, taking the chopper out of a good 9816 PSU board and
sticking it on a curver tracer won't help, you don't know what you're
looking for)
[1] A Power/Mate EVD-6S-300S IIRC.
And before someody suggests replacing the complete PSU, I should point
out hat this thing has strange outputs. +5V (normal), +15V and -15V (or
+14.4V, -14.4V?). The latter 2 are regulated down by linear regulator
circuits on the monitor PCB to give +/-12V.
[An aside for those who don't know the HP9816. It's a 68K computer with
uilt-in monitor, although no built-in drives (those connect via an HPIB
port). There are 6 PCBs in the case, and 2 expansion slots for HP DIO boards.
Flat in the bottom of the case is the processor board, which contains the
CPU, RAM (normally 256K bytes, it's possible to get 1M on there), boot
ROMs, HPIB port, RS232 port, keyboard port, etc.
THis plugs into a little backplane which carries the DIO slots
On top of that, also plugging into the backplane is the monitor PCB,
which contaisn the CRT drive circuitry and the +/-12V regulators)
Plugged into that are 2 more boards of mostly digital ICs. The larger one
is the text video circuitry, the smaller one the graphics video.
And finally there's a metal box down one side of hte mchine (LHS seen
I aquired a HP 9816 with a faulty power supply.
Thanks to the diagrams of Tony I found out that the switching transistor
QP1008 is shorted and a 2n2222 but thats no problem.
I googled for it and searched my datbooks but can't find any replacement
or
datasheet for it.
So does somebody knows the specs or a replacement for this transistor ?
Maybe I don't understand what you're asking, but the replacement for a
2N2222 is a 2N2222. They're still made, and not at all hard to find. from the back IIRC) that contains the SMPSU we're
discussing here. It
connectes by 2 camels (mains in, DC out) to connectors on the
monitor PCB]
If that's not what you're trying to replace, what is the part number
you're replacing? I could be wrong, but QP1008 looks like a component
designator, not a part number. Even if there's only an HP part number
(e.g., 181x-xxxx), that's more useful for finding a replacement than
a component designator.
There are no HP part numbers on the PSU board components.
-tony
6:35 p.m.
On Monday 14 April 2008 18:18, Tony Duell wrote:
You did those schematics? I'm impressed. It's been quite some time since
I've been quite that ambitious... :-)
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin
Rik wrote:
Err, no....
This PSU [1] has 2 transistors on the primary side. The chopper,
component reference Q2, is a TO3 can marked 'QP1008'. There's also a
current-sense transistor, Q1, a 2N2222
The latter is not a problem to replace. The 2N2222 is trivial to find,
and it's not _that__ critical anyway. But the chopper transistor is
almost certainly selected for some parameter, but I have no idea what (so
that, for example, taking the chopper out of a good 9816 PSU board and
sticking it on a curver tracer won't help, you don't know what you're
looking for)
[1] A Power/Mate EVD-6S-300S IIRC.
And before someody suggests replacing the complete PSU, I should point
out hat this thing has strange outputs. +5V (normal), +15V and -15V (or
+14.4V, -14.4V?). The latter 2 are regulated down by linear regulator
circuits on the monitor PCB to give +/-12V.
[An aside for those who don't know the HP9816. It's a 68K computer with
uilt-in monitor, although no built-in drives (those connect via an HPIB
port). There are 6 PCBs in the case, and 2 expansion slots for HP DIO
boards.
Flat in the bottom of the case is the processor board, which contains the
CPU, RAM (normally 256K bytes, it's possible to get 1M on there), boot
ROMs, HPIB port, RS232 port, keyboard port, etc.
THis plugs into a little backplane which carries the DIO slots
On top of that, also plugging into the backplane is the monitor PCB,
which contaisn the CRT drive circuitry and the +/-12V regulators)
Plugged into that are 2 more boards of mostly digital ICs. The larger one
is the text video circuitry, the smaller one the graphics video.
And finally there's a metal box down one side of hte mchine (LHS seen
from the back IIRC) that contains the SMPSU we're discussing here. It
connectes by 2 camels (mains in, DC out) to connectors on the monitor PCB]
I aquired a HP 9816 with a faulty power supply.
Thanks to the diagrams of Tony I found out that the switching
transistor QP1008 is shorted and a 2n2222 but thats no problem.
I googled for it and searched my datbooks but can't find any
replacement or
datasheet for it.
So does somebody knows the specs or a replacement for this transistor ?
Maybe I don't understand what you're asking, but the replacement for a
2N2222 is a 2N2222. They're still made, and not at all hard to find. If that's not what you're trying to
replace, what is the part number
you're replacing? I could be wrong, but QP1008 looks like a component
designator, not a part number. Even if there's only an HP part number
(e.g., 181x-xxxx), that's more useful for finding a replacement than
a component designator.
There are no HP part numbers on the PSU board components.
-tony
15 Apr
15 Apr
3:01 p.m.
You did those schematics? I'm impressed.
It's been quite some time sinc=
e=20
I've been quite that ambitious... :-)
Err, no. My cat drew them, and I simply plagarised them :-)
More seriously, yes, I've traced out the 9816 scehmatics. And many other
machines. The larger stuff is on the hpmusuem.net website, you can also
get a CD-ROM of everything from HPCC.
The 9816 was by no means the most complicated machine either (there were
a lot of helpful clues too : the DIO slot pinout was known, that gave a
lot of the signals on the CPU boartd DIN41612 connector, for example). If
you want a raal challenge, try an HP9100... Or even an HP9845
-tony
4:12 p.m.
On Tuesday 15 April 2008 18:01, Tony Duell wrote:
Well, there was a time when I might have given something like that a good
shot, but not any time recently...
On top of everything else my eyes aren't what they used to be. :-(
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin
You did those
schematics? I'm impressed. It's been quite some time
sinc= e=20
I've been quite that ambitious... :-)
Err, no. My cat drew them, and I simply plagarised them :-)
More seriously, yes, I've traced out the 9816 scehmatics. And many other
machines. The larger stuff is on the hpmusuem.net website, you can also
get a CD-ROM of everything from HPCC.
The 9816 was by no means the most complicated machine either (there were
a lot of helpful clues too : the DIO slot pinout was known, that gave a
lot of the signals on the CPU boartd DIN41612 connector, for example). If
you want a raal challenge, try an HP9100... Or even an HP9845
-tony
16 Apr
16 Apr
3:02 a.m.
Update, the PSU works again.
I used a BU208A witch seem to function fine.
As I supposed earlier C11 (220uF/16V) was leaking and destroyed the 2n2222
witch blew the QP1008.
On the secondery side there were some elco's going bad, after replacing them
the PSU is regulating ok?.
Everybody thanks for the advise (and of cause Tony's cat for the schematics)
Rik
1:51 p.m.
Update, the PSU works again.
Excellent...
I used a BU208A witch seem to function fine.
I'll make a note of that. BU208As are pretty easy to find, and it'll be
one to try if my 9816 ever has PSU prolems.
As I supposed earlier C11 (220uF/16V) was leaking and
destroyed the 2n222=
2=20
witch blew the QP1008.
On the secondery side there were some elco's going
bad, after replacing t=
hem=20
the PSU is regulating ok=E9.
It's actually a fairly standard SMPSU design, I think.
Everybody thanks for the advise (and of cause
Tony's cat for the schemati=
cs)
Enjoy the mahcine. It's one of my favourite 68K boxes. I have a 256K RAM
card in one slot of mine, and a GPIO (16 it parallel) interface in the
other. RS232 and GPIB are of course built-in.
How much memory do you have on the provessor board? Most came with 256K
(all loctaions filled with 4164s). You can increase it to 1M by replacing
all the RAMs with 41256s, fitting a 74F158 in the spare location at one
side of hte PCB, fitting a 33 Ohm (I think originally 31.6 Ohm, but it
makes no difference) resistor in the ovious positon, and cutting a couple
of jumpers (I can look up details). I've done this to my machine.
And which keyoard do you have? The 'compact' keyoard is odd in that it's
not scanned. One side of each switch is grounded, the other sides feed
banks of 4051 multiplexers.
-tony
17 Apr
17 Apr
5:46 a.m.
Enjoy the mahcine. It's one of my favourite 68K boxes. I have a 256K RAM
card in one slot of mine, and a GPIO (16 it parallel) interface in the
other. RS232 and GPIB are of course built-in.
How much memory do you have on the provessor board? Most came with 256K
(all loctaions filled with 4164s). You can increase it to 1M by replacing
all the RAMs with 41256s, fitting a 74F158 in the spare location at one
side of hte PCB, fitting a 33 Ohm (I think originally 31.6 Ohm, but it
makes no difference) resistor in the ovious positon, and cutting a couple
of jumpers (I can look up details). I've done this to my machine.
And which keyoard do you have? The 'compact' keyoard is odd in that it's
not scanned. One side of each switch is grounded, the other sides feed
banks of 4051 multiplexers.
-tony
It's a 256kB processorboard, but I have a 2M Ram board with it.
I also have a 'secondary processorboard' with a 68020 and 68882 at 25Mhz
with 4M on it from Newport Digital.
I got the small keyboard and have to share it with my 220 so if somebody has
a spare I'm in for it.
I like the machine also because it's a very compact design, and takes not
much deskspace.
Rik
3:21 p.m.
It's a 256kB processorboard, but I have a 2M Ram
board with it.
I'll include the notes I made on upgrading my 9816, but quite how you set
the switches if you have 2M RAM boaurd (which AFIAK HP never made) I
don't know.
I also have a 'secondary processorboard' with
a 68020 and 68882 at 25Mhz
with 4M on it from Newport Digital.
I'e never seen one of those (and thus can't help with schematics), but it
sounds rather nice!
I got the small keyboard and have to share it with my
220 so if somebody has
a spare I'm in for it.
Well, there's no microcontroller in the _keyboard_ (there is one on the
processor board in the mahcine, talking to the keyboard connector), so I
suppose it would be possible to make some kind of interface to another
keyboard. The interface is quite simple, after all.
I like the machine also because it's a very
compact design, and takes not
much deskspace.
It's a very neat deisgn. I'm undecided as to whether I prefer this
machine or the 9817, which has a 68010 processor, MMU and 6 DIO slots in
an 'HP shoebox' case. It has an exernal composite monitor of course and
an HP-HIL keyboard. Interestingly, the CPU boards of the 9816 and 9817
are the same size, and have very similar connecotr pinouts (the main
difference being the audio, but there are links to correct this). It
appears you could make a 9816 with a 9817 processor board or vice versa...
My 9817 has the higher-resolution video board, which uses a special
monitor, actually a Samsung chassis. And that is not pleasant to work on...
Anyway, here are the memroy upgrade notes :
Upgrading a 9816 to 1M RAM on the processor board
-------------------------------------------------
These instructions assume you're starting with a 256K processor board,
that is one with 32 4164 DRAMs fitted.
Firslty remove the processor board. To do this, disconnect all cables
from the rear of the 9816, then remove the DIO slot
cover plate (or a DIO
board witu an external connector). Remove any DIO boards in
the slots --
memory voards will need to have their addresses chaged after this
modification. Release the 2 quarter-turn fasteners on the rear of the
machine and free the top cover from the clips under the back edge of the
machine. Slide the cover rearwards, lift it off, and unplug the fan cable
from the monitor PCB. Pull the processor board -- at
the very bottom of
the machine -- rearwards, unclip the earth wire fromthe faston
tab on the
RS232 connector. Slide the processor board all the way out.
Now to upgrade the RAM. Desolder all 32 DRAMs from the board. These are
in 2 rows at the very front edge. Leave the clock oscillator can,
reset-circuit transsitor array, and resistor pack in place. Clear out the
pads for U122 (to the right of the rear row of DRAMs) and R47 (leftmost
resistor in the block of 3 resisotrs to the left of the ROMs) At this
stage both of those locations should be empty.
Fit 32 41256 (256K*1) DRAMs in place of the 64K ones that were just
removed. Fit a 74F158 at U122 and a 33 Ohm resistor at R47
Cut J11 and J12 (in front of the DIP switch array). Cut J8 1-2 and link
2-3 (this likn is in fornt of U34, near the ROMs).
Turn off all sections of SW3 (frontmost DIP switch). Sections 5-7 _must_
be off or the RMA will be diabled, sections 1-4 set the address of the
RAM. It's simplest to have them all off, which makes the processor board
RAM appear at the top of the memory map, then to address all other boards
following the HP instructions, regarding the processor board RAM as a 1M
board set to '0'.
Refit the processor board, conencting the ground wire. Plug in the mains
cable and power up. The screen should report a little under 1M free. If
all appeears to be working, switch the unit off, unplug the mains cable,
and refit the covers, DIO board(s) and cables.
-tony
14 Apr
14 Apr
2:16 p.m.
On Mon, 2008-04-14 at 22:56 +0200, Rik wrote:
I aquired a HP 9816 with a faulty power supply.
Thanks to the diagrams of Tony I found out that the switching transistor
QP1008 is shorted and a 2n2222 but thats no problem.
I googled for it and searched my datbooks but can't find any replacement or
datasheet for it.
Uhm, a 2N2222 is incredibly common, and is pretty much just a generic
NPN small-signal tranny.
Use anything. Unless of course Tony points out some clever idiosyncrasy
that makes it the only part to use here ;-)
Gordon
3:03 p.m.
I aquired a HP 9816 with a faulty power supply.
I asusme this is the SMPSU board in the metal case at one side of the
machine, and not the +/-12V regulators on the monitor PCB.
Thanks to the diagrams of Tony I found out that the
switching transistor
QP1008 is shorted and a 2n2222 but thats no problem.
As you've probably noticed by now, this PSU was not made by HP. At least
in my machine it was made byt 'Power/Mate'. Not that this helps very much.
I googled for it and searched my datbooks but
can't find any replacement or
datasheet for it.
Nor can I. My guess is that the it's a 'house number', and that the
trnasistor was selected for some particular characteristic.
My furst guess would be a 2SC1942, since that seems to work in many small
SMPUS, but don't blame me if it shorts at switch-on. And of course if it
doesn't you won;t know if that was becuase it was an unsuitale transistor
or because the origianl fault is still there.
I would certainly check all the secondary-side rectifiers and smoothing
capacitors. And the snuber componets (R6, CR4, C12, C3, CR5)
I assume that some of the low-value resistors in the Q2's emitter circuit
have burnt out too. Any open PCB traces?
-tony
15 Apr
15 Apr
1:58 a.m.
I'm replacing the elco C11 because it's expanding and I suspect it to leak ,
and yes I'm going to check the other components.
I didn't find any open pcb-traces yet but will check this too .
I'll keep you posted on this.
Thanks, Rik
----- Original Message -----
From: "Tony Duell" <ard at p850ug1.demon.co.uk>
To: <cctalk at classiccmp.org>
Sent: Tuesday, April 15, 2008 12:03 AM
Subject: Re: Replacement for QP1008 (HP9816 PSU)
I won't, I'm happy with every suggestion.
>
> I aquired a HP 9816 with a faulty power supply.
I asusme this is the SMPSU board in the metal case at
one side of the
machine, and not the +/-12V regulators on the monitor PCB.
YES, your right.
Thanks to the
diagrams of Tony I found out that the switching transistor
QP1008 is shorted and a 2n2222 but thats no problem.
As you've probably noticed by now, this PSU was not made by HP. At least
in my machine it was made byt 'Power/Mate'. Not that this helps very much.
I googled for it and searched my datbooks but
can't find any replacement
or
datasheet for it.
Nor can I. My guess is that the it's a 'house number', and that the
trnasistor was selected for some particular characteristic.
My furst guess would be a 2SC1942, since that seems to work in many small
SMPUS, but don't blame me if it shorts at switch-on. And of course if it
doesn't you won;t know if that was becuase it was an unsuitale transistor
or because the origianl fault is still there. I would certainly check all the secondary-side
rectifiers and smoothing
capacitors. And the snuber componets (R6, CR4, C12, C3, CR5)
I assume that some of the low-value resistors in the Q2's emitter circuit
have burnt out too. Any open PCB traces?
-tony
6094
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6097
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17 comments
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participants (6)
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ard＠p850ug1.demon.co.uk -
dr.emiel＠xs4all.nl -
eric＠brouhaha.com -
gordonjcp＠gjcp.net -
hilpert＠cs.ubc.ca -
rtellason＠verizon.net