3 Oct
2008
3 Oct
'08
6:13 p.m.
On Friday 03 October 2008 14:41, Tony Duell wrote:
They're not generic, in that they don't fit more than 1 types of
TV/monitor, but they're not really OEM parts, in that I suspect the
original flyback came from a different supplier. I suspect in some cases
the original was reverse-engineered and said third-party company came up
with a functional equivalent. It's only worth their while to do this if
they are likely to sell many of them, of course, so the HP9836C is not
going to be on the list...
Hmm.
[HP's odd designs]
They actually put ROM sources in the patent? Wow. I wouldn't have expected
that. What I would like, if not stuff quite so detailed, is something
along the lines of "this is how it's supposed to act" for a lot of stuff out
there. Like all those VCRs that I encountered that simply wouldn't turn on,
where I went looking for power supply and all sorts of other issues initially
only to find that if the controller chip in there didn't get what it
considered to be a sensible response from the mechanism when it tried to move
things it would give up. Causes were as simple as bad belts, etc.
Some engineer got very clever there, it sounds
like, and then somebody
else in the hierarchy decided not to let you in on how that worked, in
detail...
That reminds me, in passing, of the HP98x0. The 'service manuals' are
boardswapper guides with PSU schematics only. But HP patented the
machines, and the patents (I have a list of the numbers, I think they're
also on Eric Smith's site) are several hundred pages each, and include
such interesting things as schematics (albeit of pre-production
machines), interface schematics, the machine language instruction set,
ROM sources (sysrem firmware and many of the expansion ROMs, etc). In
other words what _should_ have been in the service manual... [...]
I will emphasise that again. The best tools/test equipment/CAD
system/whatever are no use at all unless you think about what you are
doing and use them intellegently.
I had the good fortune to have a teacher way back when who knew this stuff
well, and who taught me how to troubleshoot, though some of that was late
in coming to fruition. :-)
Over 10
years ago I bought an HP LogicDart. It was expensive, but I
have never regretted it. I've got other instrumetns that do all it will
do and more, but that's a useful handheld tool that will find 99% of
digital faults in classic computers, if used with that most important
piece of diagnostic equipment -- the thing inside your head.
Yes... The 3rd-party suppliers over here will sell you a
flyback for TV model
<foo> or monitor <bar> but they don't give any more details than that.
A generic replacement type flyback? Or an OEM part? If it's the former
then maybe there's some hope. I must admit I've never had any success with these
third-party flybacks.
I had an Amstrad VGA monitor with flyback trouble (the voltage divider
block for the focus and A1 supply was reaking down),
Snap, Crackle, Pop! :-)
I ordered the so-called replacement and fortunately I
checked out the
winding connections before fitting it (that is, I checked which pins were
connected by windings, which sets were totally isolated). I say
fortunately, because if I'd fitted it, the 100V or so output from the
monitor's SMPUS would have been directly connected to the CRT heater!. In
the end Iought the genuine Amstrad part (yes, it was available, it was
also a lot more expensive) and had no prolems.
Interesting. And yes, I've encountered the occasoinal bad cross-reference
too, though thankfully they're not all that common.
--
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