16 May
2008
16 May
'08
2:10 a.m.
On Thursday 15 May 2008 19:48, Ade Vickers wrote:
(Snip)
I believe so, though it's been a long time and I can't be 100% certain of it.
Not necesarily.
I've not counted the pins, but one thing - where's the brightness control
go? The machine has external (to the monitor) controls for both contrast &
bright; as well as trimpots for both on the monitor PCB itself.
Darn, I *really* need to find my schematics on this stuff... :-)
(Snip)
--
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
Maybe I should monitor the PSU voltage on the
'scope while the machine's
booting - I hadn't thought of that one. Could be interesting - the bulk of
the computer is currently upside down on the bench to make it easy to
access the bits of the PSU I need to probe... if the 5v line is flapping
about, this could cause the digital effects. Mind you, the fact the machine
boots properly indicates that the logic side of the machine is working
fine; and I'd have thought the disk drive would be more sensitive to 12v
fluctuations than the monitor?
The drive only uses the 12V for the spindle motor, I think, but do check
them both.
And clean the edge connectors for the drive ribbon cable too, that's been a
trouble spot in my experience, what with them running power through the
ribbon cable.
Does this
machine use a 6845 or similar for hre video timing
chain?
Dunno, will look tomorrow (err, later today). If so,
mis-programming that will cause apparent sync
problems. So the fault could bever well be proscessor, ROM,
or bus related.
Bearing in mind the machine boots, and works behind its corrupted video
output, would that necessarily eliminate any of those parts from enquiries? That's why
I'd start by looking at the horizotnal sync pulses
when you have the lines and when you have a good display
(even if the machine has crashed). If they're the same
timing, then the fault is monotor (or PSU?) releated. If not,
then the video timing circuitry is palying up _or being
mis-configured by software_
Gotcha - will look at that tomorrow.
I'll
look for it... the monitor circuit board is quite well labeled; but
I'm not sure if the connectors themselves have individually labelled
connections.
Sony were sometimes kind enough to label connector pins,
supply lines, CRT pinouts, etc in the slikscreen, few other
manufacturers were.
If it is a standard pinout, then the connections are
1 Ground
2 One end of the contrast control
3 t'other end of the contrast control
4 Slider of the contrast control
5 ground
6 Hsync
7 +12V power input
8 video input
9 Vsync
10 ground