Subject:
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Re: Serial LED is not lighting up = pilot error
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Mon, 3 Sep 2001 08:13:17 GMT
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Viewed:
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1867 times
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I believe I've determined the problem. It looks like pilot error. Upon closer
inspection of the serial LED, I noticed that it was defintely backwards in
comparison to the power LED. I know that the power LED works like it should so
the serial LED must have been in wrong. Now my problem is, when I attempted
to remove the serial LED and re-install it, one of the leads came out of the
plastic dome.
My next question is, where do I find the specs for these LED's? I've looked up
the part number on Digikey but they don't seem to offer much in the way of
technical specifications (Current and Voltage settings). Followed the part to
Fairchild Semiconductor and was able to download a PDF spec sheet but I'm still
having a problem with determining the "simple" specs. All I want to do is go
down to the local electronics store and pick up a replacement LED (or 10).
However, the pack that I decided on has current and voltage numbers on the
front and I haven't been able to find a similar set of numbers for the Digikey
part (Fairchild part either).
What I bought says 10mA, 3V. I'm still not sure what came with the Acroname
kit. I will give them a call on Tuesday but if anyone has any suggestions or
information on the current/voltage settins for these LED's I would appreciate a
pointer. Sorry to keep clogging up the list with such newbie questions. Its
been a long time since I had any electronics. Rusty doesn't even begin to
cover it now. Thanks.
Scott
In lugnet.robotics.handyboard, Rainer Balzerowski writes:
> Hi Scott,
>
> as I mentioned before i only assembled some 6.270 boards, but no handyboard.
> So what's follwing is only what i guess.
> I can't check this out here.
>
> Are you able to measure (always with pin7 J9 as ground reference) +9V at
> pin2 U16 and -9V at pin6 U16 ?
>
> If so then you're connecting pin6 U16 to pin2 J9 (or pin 8 U16 which is the
> same). That means -9V to the (resistor in series !! or our LED will light up
> bright but a short time and only once !) cathode of the green LED. The anode
> should be connected to ground in the circuit (pin7 J9 and the anode of the
> LED should have a connection).
> (Have a look at hbmanual.pdf page 52)
>
> When doing so the LED should light up.
>
> If not your LED might be blown or the wrong direction, but you're sure that
> it's not. Or your resitor in series with LED is blown (or the wrong one, it
> limits the current of the LED. So if it's the wrong one the LED won't light
> up (or one short time, very bright :( )
>
> Regards,
>
> Rainer
>
> In lugnet.robotics.handyboard, Scott Hazel writes:
> > I'm in the middle of assembling the Serial Interface and Batt. Charger
> > board but have run into a snag. While testing the serial circuit, I was
> > able to see the +-9V values on pin 2 of U16. However, when testing the
> > transmit and receive functions of the MAX232 chip, I can't get the green LED
> > to light up. There are no troubleshooting/debugging tips for this section.
> > I'm pretty sure
> > that I installed the LED correctly. The short lead is the cathode
> > (negative) and goes into the square hole for SER LED. If this LED was
> > installed backwards, would that account for getting the right voltages but
> > no light?
> >
> > One caveat on my part, I misunderstood the directions and have already
> > installed the 25pin Serial connector (J9) so I've been making my
> > measurements with a bare lead inserted into the proper hole (pin 7, etc.) I
> > don't see how that would impact this problem but its best not to leave any
> > details out. Any suggestions on how to troubleshoot the serial LED not
> > lighting up? Thanks.
> >
> > Scott
> >
> > _________________________________________________________________
> > Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp
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