Been there, done that...
The programming voltage internal to the Picstart is fairly critical and is
generated from a step-up DC-DC converter.  Cranking in the higher voltages
from a cheap wall-wart can crank the programming voltages well above where
they need to be.  The PicStart says 9.0 volts.  Give it 9.0 Volts.  The
older microchip supplies have failed--I've gone through two of them so far.
 In both cases, the picstart started working normally.  Nominal 12-volt
wall-warts can put out 17-20 volts under low load.  They are NOT regulated
in most cases.

MicroChip replaced my power supply, no questions asked--although I did have
to go through the local rep for an RMA number.  Ditto for the Picstart if
necessary.

I have had problems with communications as well.  Seemed to be dependent on
the state of my system.  For programming, I normally power everything down,
re-power and reboot the main system.  Power up the picstart, bring up
mplab, then connect the Picstart to the serial port.  Usually will
talk--but not always.  Protel 99SE grabbed my com1 port and would not let
go, so there are known conflicts at the operating system level with windows
98.  If this happens, try moving MPlab to a different system and see of the
problem moves as well.

Kelly





At 02:06 PM 2/15/00 -0500, you wrote:
>I am using a PICStart Plus with the original power supply that came with
>the machine when I purchased it two years ago.  I have had progressive
>difficulties with the programmer in the past two days.  The problems
>usually are characterized by a message from MPLAB instructing me to
>check the power and serial connections and/or reset the programmer.  The
>PICStart Plus is rated for a 9VDC input; also the output rating of the
>power supply I am using.  I have measured  the power supply output and
>found close to 12VDC even when plugged into the programmer.  I say the
>problem was progressive because it was initially manifest as the
>occasional inability of MPLAB to talk to the programmer.  This became
>more frequent and finally resulted in failure to program a 16C84  and
>then the complete inability to talk to the PICStart Plus from MPLAB.
>
>I know it isn't unusual for a power supply to show a voltage different
>from the nameplate rating, but 12VDC in lieu of 9VDC seems excessive.
>Does anybody have any experience with how tolerant of variations of
>input voltage the PICStart Plus programmer might be?
>
>Thank you for your consideration,
>
>Andrew McDermott
>
>
William K. Borsum, P.E. -- OEM Dataloggers and Instrumentation Systems
<borsum@dascor.com> & <www.dascor.com>San Diego, California, USA