16 May
2008
16 May
'08
5:01 a.m.
Tony Duell wrote:
There is a de-facto 'standard' for 10 pin
monitors (using a
0/156" pitch edge connector or header plug). The DEC VT100
monitor PCB is one such, if you need more details...
Looks like the standard has been used... enough pins seemed to match up with
your description, that I went with it.
So, here are the two traces, hsync & vsync:
http://www.solutionengineer.com/ozzie/hsync.jpg
http://www.solutionengineer.com/ozzie/vsync.jpg
Apologies about the quality of the hsync one, the camera seems to have
refocussed itself on its own reflection...
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_
H-sync pulses (and the vsync, for what it's worth) are identical when the
machine is crashed or running. However, I don't understand why that would
put the fault in the monitor? And it still doesn't explain the digital
artifacts...
There does seem to be a significant amount of noise coming off the board; I
could get a reading on the 'scope when the probe was a good 2-3cm away from
the board - not sure WHAT signal, just a square-ish peak in the middle of
the screen...
Cheers!
Ade.
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19:25