Subject:
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Re: Help debugging.
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Sun, 2 Jun 1996 14:15:19 GMT
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Original-From:
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Fred G. Martin <fredm@media.mit.edu(stopspam)>
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Viewed:
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1760 times
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> In the interface/charger serial circuit, I get 17 volts at pin 2 and I get
> 0 volts on pin 6. The MAX232 chip is oriented to the right, and all the
> capacitors have their negative stripes on the left - matched up to the
> square pads and the picture of the board on the web...The test for the
> first section checked out fine.
which pin were you using as ground reference? Maybe redo your test
using pin 15 of the Maxim as ground. First check the Maxim is getting
good power and ground (pin 15 is ground, pin 16 is +5). Then re-check
the voltages on pin 2 (should be +9 to +10) and pin 6 (-9 to -10).
if this fails check, the voltages across each of the 4 charge-pump
capacitors -- C10 through C13. Check each cap individually with the
black (minus) probe going to its square pad; C10 and C12 should have a
+5v potential, and C11 and C13 should each have a +9 or +10 potential.
if the maxim really has just the normal +5v on its power pin (16),
then there's no way it can generate 17 volts. i'm guessing that you
must have used a -10v point for your ground reference in your initial
testing, which would explain the voltages you got.
-Fred
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Message has 1 Reply:
 | | Re: Help debugging.
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| Okay - thanks - you were right - I mis-read the ground location and used pin 7 of the MAX232 instead of using pin 7 of J9. The chip is getting 5 volt range, but the negative voltages are in the mid-8 range - is this something to worry about? thanks (...) (28 years ago, 2-Jun-96, to lugnet.robotics.handyboard)
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Message is in Reply To:
| | Help debugging.
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| Well, I didn't get far without running into a bug. In the interface/charger serial circuit, I get 17 volts at pin 2 and I get 0 volts on pin 6. The MAX232 chip is oriented to the right, and all the capacitors have their negative stripes on the left (...) (28 years ago, 2-Jun-96, to lugnet.robotics.handyboard)
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