12 Jul
2005
12 Jul
'05
7:45 p.m.
Its my understanding (but I've only seen it as a
rumor, not as hard
technical fact) that the reason the original IBM Monitors plug into the
PC Power Supply and not directly into an outlet is that they were
vulnerable to damage (probably the same horizontal drive problem) if
left powered on independent of the PC.
I've heard that rumour too, but I can't understand why, after looking at
the schematics. The horizontal drive is transformer-coupled, so it
doesn't matter if the input gets stuck high or low, it still won't turn
on the output transsitor.
I at one point had an original IBM monitor that had a direct power cord
connector and understood at the time that it was one of the very early
The CGA and EGA nonitors of course connect separately to the mains. The
MDA monitor has a built-in power cable ending in an IEC plug that would,
in theroy, fit into a normal 'kettle lead'. AFAIK all were built like that.
I am using a 5151 now. On the grounds it doesn't have a power switch of
its own, I plug it into the outlet on the system unit PSU. I suspect,
though, it would do no damage to power it separately.
-tony