Subject:
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Re: HD LCD problems
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Thu, 17 Dec 1998 18:12:15 GMT
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Original-From:
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john calhoun <calhoun1@apple.com%NoMoreSpam%>
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Viewed:
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1061 times
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> I encountered some problem in the downloading. I was successfully able to
> download the p_code into the HD. However, When the instruction proned me
> to reset the board,it always appears on the LCD without any lettering like
> "version 3.1...."on it . It is just blank with '16 dark squares' printing
> on the LCD.
On a lark, I'll suggest that perhaps U6 is damaged. If you have another
74HC138 around, try swapping it for the one on your HB. I had a
"similar" problem (although not identical) and was able to diagnose the
74HC138 as the problem.
I too was seeing occassional failures to come up and often saw instead
the 16 black elements across the LCD display.
I also saw that when I removed the LCD while the board was running and
re-inserted it, I often also go the 16 black elements. I don't know if
this helps shed any light.
I have now 3 Handy Boards and one was not working correctly. I was able
to narrow it down to U5 or U6 and with a simple chip swap with one of the
good HB's found it to be the 74HC138. BTW, everytime I pulled the chip,
all the p_code had to be re-downloaded again - pulling the chip seems to
do a complete brain drain.
If you have an extra 74HC138 lying around, it's certainly worth a try.
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