Subject:
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Re: Trouble with handyboards
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Wed, 4 Oct 2000 16:45:21 GMT
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Reply-To:
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GLIVICK@nospamPACBELL.NET
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Viewed:
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907 times
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It is common when polarized caps are put in backwards! Some of those
little beggars are hard to see, and easy to get backwards. Other
things, such as solder bridges or bad solder joints, can be a problem.
Some have even reported finding debris under there processor chips as
they sit in the socket that shorts out pins sometimes, sometimes not.
The problems you are experiencing are user generated. Once in a great
while a hex inverter chip goes out and causes some problems, but that is
rare and would not be expected to occur in a bunch of boards.
To start off in figuring out what is going on, check for 5 volts in
various parts of the circuit. A short somewhere will pull the voltage
down. Next, feel around for things that are getting hot. Start with
the voltage regulator, it gets warm but should not be so hot that you
cannot touch it. Then feel the caps, if one is backwards they you can
get a nice blister on your finger from it. Feel the ICs for one to be
getting hot. Then check all your solder joints slowly and
methodically. Finally, start pulling chips and swapping them from a
known good board. Somewhere in the course of this, you'll find the
problem.... probably.
Good luck,
Gary Livick
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Message is in Reply To:
 | | Trouble with handyboards
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| I am having students in one of my classes build handyboards, and most are working fine, but some are failing. They all passed intermediate tests, but failed when fully assembled. The most common failure mode that I am seeing results in the (...) (24 years ago, 4-Oct-00, to lugnet.robotics.handyboard)
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