Testing a 1488 line driver...
Roy J. Tellason
rtellason at verizon.net
Wed Jan 2 23:12:22 CST 2008
On Wednesday 02 January 2008 22:50, Gene Buckle wrote:
> > On Wednesday 02 January 2008 22:10, Gene Buckle wrote:
> >> I used an LED to watch the output on the 1488.
> > With an appropriate current-limiting resistor I would assume?
> I actually used a little light bar I have that has 3 12V LED assemblies on
> it. I ended up using this after my resistor decade box died on me and I
> couldn't find a 500 Ohm resistor. :)
Why I salvage all sorts of parts...
> >> The LED lights the instant I attach it to the output and doesn't flicker
> >> or go out when I reboot the computer to make it send data out the port.
> > The little tester I have for rs232 stuff uses bi-color LEDs, makes it
> > easier to see what's going on.
> I've got one of those as well - it never shows a state change. I tried
> that first.
Well, there ya go then.
> > Could be, I've certainly replaced my share of those. And put sockets in
> > while I was at it. :-) Just make sure it's getting the proper power
> > supplies, as if one or both of them are missing you won't see proper
> > output then, either.
> I did check the power first. :) 12V like it's supposed to be. If I have
> to pull the board, I'll certainly put in a socket. :)
Both plus and minus 12V? You do need both.
If there's no change in the LED indicator, and the input that drives it is
changing, then yeah, it's probably toast.
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