Subject:
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Re: handy board troubles...
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Tue, 21 Mar 2000 23:11:09 GMT
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Viewed:
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1346 times
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re: this problem with the memory contents not persisting, check the
separate power supply to the RAM (U14). you might need to remove all
socketed ICs from the board 'cause power can bleed to chips via input
pins.
also check that U12 the DS1233 is working. when you turn the HB on,
the low batt led should come on for 1/3 sec.
i doubt it's the ram if things work normally otherwise.
btw the HM6264 chip is 64k *bits*, i.e., 8k bytes. won't work, use
the 62256 variety.
fred
In your message you said:
> In lugnet.robotics.handyboard, Jake Burkholder writes:
> > In lugnet.robotics.handyboard, John Wynne writes:
> > > Actually Jake, I'm having a similar problem right now, with regard to
> > > loss of RAM capabilities.
> > >
> > > I've been testing a new Polaroid 6500 sonar (which now works!) on the HB
> > > and I've got it hooked up through the exp. board. I tried to run a simple
> Yes! I apologize, I meant "..._without_ the RJ11 cord connected..."
>
> Is it possible a surge could have fried the RAM and now it won't
> hold memory? That was my contention, but I'm not sure...
>
> John
>
> p.s. RAM replacement question: Will any 64K CMOS SRAM 28 pin chip work?
> I have a HM6264P-12 120ns RAM chip that I bought today, and was wondering if
> I might expect problems (due to difference from the recommended RAM chip)...
> Thanks!
>
>
>
> > > program that used actuated two servos, two motors, while polling one analog
> > > input. It seemed to work without the Polaroid connected, but when I fired
> > > it up with everything loaded on, it died, and now my HB can't seem to hold
> > > it's RAM with the RJ11 cord connected to the charger/dler. I'm not complete • ly
> > ^^^^
> > Do you mean without? That's my problem; the board only holds its data if
> > the cord is plugged in.
> >
> > > sure how the servos are powered/oscillated (etc.) so I haven't been able
> > > to locate where I might have suffered some kind of power surge (possibly
> > > from the sonar ranging board)... does it make any sense to think that
> > > the sonar could have any affect on other periferals without being directly
> > > powered up?... How ARE the servos on the Exp. Board driven?
> >
> > I've also got a servo which I can't figure out how to drive from the
> > exp. board, but the problem of the RAM discharging happens even with a
> > bare board (no exp., no lcd).
> >
> > I'm convinced its a voltage problem and was going to try replacing the fuse
> > at F1 next.
>
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Message has 1 Reply:
Message is in Reply To:
 | | Re: handy board troubles...
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| (...) Yes! I apologize, I meant "..._without_ the RJ11 cord connected..." Is it possible a surge could have fried the RAM and now it won't hold memory? That was my contention, but I'm not sure... John p.s. RAM replacement question: Will any 64K CMOS (...) (25 years ago, 21-Mar-00, to lugnet.robotics.handyboard)
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