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 11:37:38 GMT
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Viewed:
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1795 times
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Hi Scott,
the handyboard part-list says that this LEDs are from the HLMP17xx series.
These LEDs are low-current LEDs and only need 2 mA current at (1.8V) 1.9V
forward voltage.
So your 10mA 3V LEDs doesn't fit.
Have a look at :
http://www.sli-lighting.com/cml/databookpdf/1-62.pdf
Instead you can use LEDs from the TLLx4400 series.
(TLLR4400 - red ; TLLY4400 - yellow ; TLLG4400 - green)
Regards,
Rainer
In lugnet.robotics.handyboard, Scott Hazel writes:
> 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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