Schematics of HP 9845b

From: Joe <>
Date: Mon Mar 4 17:23:30 2002

    The power supply in the 9845 isn't likely to resemble that in the 9825.
The 9845 PS is a shoe box sized unit that sits below and between the two
pillars that support the monitor. Inside it has one large circuit board and
four more circuit boards that plug into it around the edges so that it
resembles a box with an open top.

  I just pulled out the dead one that I still had laying around here. It
has a number of test points on the top. One group of four with + 17 VDC,
-17 VDC, +13 VDC and Gnd 2. Another group of four with two of them plugged.
The reamining two are marked "C 18 175 VDC Max" across them. Then two
individaul ones on the top RH side that say 12 VDC and Logic Gnd. Below
them is five more in a zig zag pattern. They're marked +5 VDC, -12 VDC,
+18VDC, +7 VDC and - 18 VDC.

   FWIW IIRC the other style didn't have test points on it but it seems to
be more reliable. I think all the ones of this style that I've seen have
had problems. This one has a large choke that's broken away from the board
and all of it's pins is broken off flush with it's housing. It could
probably be drilled out and the wires reconnected but I didn't bother since
I had other PSs. I don't know if this PS has any other problems.


At 10:35 PM 3/4/02 +0000, you wrote:
>> Hello all,
>> I'm very sad - finally my HP9845b is dead!
>> I'm beleaving, it's a problem with the power supply. Some years ago I
>> changed some capacitors already.
>How similar is the PSU to that in the HP9825? I have a reasonable amount
>of info on that machine.
>In particular, what are the part number(s) on the PSU board(s). The first
>5 digits normally give the machine where the board was first used, which
>can be a help in tracking down info.
Received on Mon Mar 04 2002 - 17:23:30 GMT

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