Subject:
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Re: pcode downloading
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Fri, 3 Jan 1997 05:52:56 GMT
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Original-From:
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Fred G. Martin <[fredm@media.mit.edu]ihatespam[]>
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Viewed:
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1522 times
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> > I assume you are successful in getting the -10 v out from pin 3 of J9
> > when nothing is attached -- what voltage do you get when you jumper
> > pins 6 and 10? You need to get at least +5v; this is the way that the
> > HB transmits back to the host computer.
>
> I get -8.9v when its not jumped. When jumped I get some floating values
> in the mV range. I checked all of the solder joints. Changed power
> supplies. Removed and reseated the chip. Checked power and continuity at
> various points around the board and things look fine.
OK, well I think it is isolated at the pseudo-MAX232 chip. Did you
get the +10 v power supply pin on the p-MAX ok? It's at pin 2.
Measure it w/r/t ground and you should get +10v.
Before you order a real Maxim, check the polarity of your
electrolytics. Also, it is possible that one of them is marked wrong.
I have seen this---electrolytics with their wrapper on backward so you
install it wrong. I am not kidding.
Measure the voltage across each of the 10uF electro's. Two of them
should have 5v across their terminals, two of them should have 10
volts.
-Fred
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Message has 1 Reply:
 | | Re: pcode downloading
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| (...) Yep, that checks out. (...) I get the correct voltages for the caps. And if the wrappers are on correctly they should all have the correct polarity. I ordered a replacement MAX232CPE (not the high speed "A" version). Hopefully this will either (...) (28 years ago, 3-Jan-97, to lugnet.robotics.handyboard)
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Message is in Reply To:
| | Re: pcode downloading
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| (...) : (...) I get -8.9v when its not jumped. When jumped I get some floating values in the mV range. I checked all of the solder joints. Changed power supplies. Removed and reseated the chip. Checked power and continuity at various points around (...) (28 years ago, 3-Jan-97, to lugnet.robotics.handyboard)
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