16 Sep
2007
16 Sep
'07
9:32 p.m.
No, but I didn't specify that I meant the keyboard
and mouse ports
(though there was some chatter about it. My concern is with things
such as printer and RS232 ports using the same connector, or putting
Of course the DB25 conneoctr has been used for all sorts of things, not
only computer-related. IIRC, the original ones were rated for 750V, so
it's not unhard-of for them to be carrying the HT+ (B+) line in valved
equipment.
Hoewever, you can also go too far the other way and end up with wha the
Hacker's Dictionary refers to as 'Connector Conspiracy'. When the only
thing that can plug in is the manufacturer's cabe/peripheral. This makes
life very difficult for the likes of us 10 years on when said cables are
long-since unobtainable.
power on connector pins where it's possible to
insert the connector
"upside down". Or using a power connector and wiring it differently
than the rest of the world (e.g. MD2 diskette drives as opposed to
anyone's 3.5" diskette drive). I believe that a few old Calcomp 8"
floppies actually put mains power through the signal connector on a
couple of models.
I find that very hard to believe. I would be suprised if most (if any)
signal connecotres met the approvale requirements for a mains connector.
[...]
Take a look at a dozen bits of equipment with wall
warts and you'll
note that many carry an entirely different branding than the
equipment they power. So matching brands won't work. And even when
Some of my classic-computer devices (mostly Japanese handhelds and
laptops) Have something like 'Use only AC adpater model <foo>' on the
lavel, or moulded into the case. I assume the origianl adapter had <foor?
written on it somwhere. Which is fine if you have the original adpater,
less useful if you don't and need tp rig something up using a bench
supply and normal components.
there are matching brands, there's no specific
information that a
Sony CD player PSU belongs to the CD player and not the DAT drive
sitting next to it. And so on.
It's inexcusable IMHO when 2 related devices from the same manufactuer
have different power requirements, come with different wall-warts, but
use the same power connector. That's just asking for trouble,
It also suprises me how few devices have even revers-polarity protection
on the input. I would have thought it would be worth including a diode in
each device, but anyway...
I have several of those "universal" wall
warts and find them to be
I don't trust wall-warts at all. IMHO they're downright dangerous, most
have no proper overcurrent protection. I've had the unversal type get hot
enough to melt the case when the '9V battery connector' on the output
side happened to touch one of the outers of the 4-ended plug on the same
output, thus short-circuiting the supply. There was no internal fuse and
the supposed safe fusing of the transformer windings simply didn't
happen.
useful also. I also keep a doublet (magnifier) handy
for deciphering
those connector symbols.
I've been knopwn to dismandle the device and trace out enough od the
circuitry to work out what it's expecting. That's if I don't have the
service manual, of course.
-tony