Yikes,

Mine is an -R4, and I've never done this mod!

Any quick ideas of what problems this is likely to have caused me?

Maybe I'm Ok because of the specific chips I've used:

16C84 16F84A 12C50x 12C50xA 18Cxxx 16C505 16F87x

?

Bob Ammerman
RAm Systems
(contract development of high performance, high function, low-level
software)

----- Original Message -----
From: Roman Black <fastvid@EZY.NET.AU>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Monday, February 26, 2001 10:52 PM
Subject: Re: [PIC]: Picstart upgrade (voltage trim)


> Spehro Pefhany wrote:
> >
> > 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.
> >
>
>
> Fair enough. Mine is a revision R11, so i didn't need
> to do this. Mine is pretty old though, a <R7 unit
> would have to be a few years old. :o)
> -Roman
>
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