piclist 2001\02\26\224059a >
Thread: Picstart upgrade (voltage trim)
www.piclist.com/techref/power.htm?key=voltage
picon face BY : Spehro Pefhany email (remove spam text)



At 02:30 PM 2/27/01 +1100, you wrote:
>Spehro, I think the PicStart Plus has the voltage controlled
>by firmware. I just replaced the main firmware chip in mine
>with the new one. It now works perfect. :o)
>-Roman

Thanks, someone was kind enough to send it to me. I'll copy it here,
just so it's in the archives:

(This only applies to early versions- 7.0 or lower).
But then I have an original Picstart programmer (not the plus)
kicking around somewhere.

:-)

===============================================================

NOTE: There has been an update to Picstart Plus Hardware to
change the Vpp programming voltage to comply with newly revised
programming specification.

PICSTART Plus Vpp Adjustment
Overview:  In keeping current with Microchips programming
specifications, any PICSTART Plus, Revision 7 or lower,  may
need a slight adjustment of the Vpp voltage.  This adjustment
will bring the Vpp voltage from a nominal 13.75volts to a
nominal 13.00 volts.  This is due to the update of the programming
specifications after the introduction of the PICSTART Plus.

To identify the revision of PICSTART Plus, look at the label on
the back, the serial number will end in a -Rx where x is the
current revision of the PICSTART Plus( Look for a value of -R7
or Lower).  There are two ways to adjust the Vpp Voltage to the
nominal 13.00 Volts.

Method 1:  Locate resistor R4, and solder a 562Kohm 1% resistor
across R4.  This will lower the value of R4 and lower the Vpp
voltage to a nominal 13.00V.

Method 2:  Locate resistor R4, and remove R4 and replace with
a 22.6Kohm 1% resistor. This will  lower the Vpp voltage to a
nominal 13.00V.


Validation:  After completing either of the above methods for
compliance, Apply 9V to the PICSTART Plus and measure the voltage
across Capacitor C5.  It should be a nominal 13.00(12.75 -13.25)
volts.  If this is correct, the modification is complete.  If this
is not correct, make sure that the method was properly followed
and there are no solder shorts near where re-work was performed.

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Subject (change) Picstart upgrade (voltage trim)

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