15 Apr
2008
15 Apr
'08
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