13 Apr
2008
13 Apr
'08
7:59 p.m.
From: ard at p850ug1.demon.co.uk
---snip---
FWIW, there have been some very complicated SMPUs in classic machines.
The HP9845B, a complicated machine in all respsects, has a PSU on a
3-dimentional sculpture of PCBs, with 4 chopper transistors, 2 main
chopper transformes, and IIRC 17 ICs on the control PCB.
Hi Tony
I have a HP 21mx. The switcher in there is one of the most complicated
that I've ever seen. When I first got it, it took me a while of studying
the schematics before I realized it needed the resistor that was suppose
to be the thermal sense in the battery pack.
This group was great in helping get the right value and connector.
I think the switcher the fellow is looking at is the typical type used
in most PC's. It does sound like he may be able to get enough parts
to put together a working PS. It is at least worth a try.
Both cases may have issued in the primary side though.
Dwight
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