Hi all,
  I've just built a David Tait "Classic" PIC Programmer from the schematics
that are floating around the 'net (PP.PCX). In the process, I removed the
78L12 and replaced it with a Maxim MAX662 that's currently wired so that its
output is locked at 12V. Now, this programmer works fine on most of my
PIC collection - 16F628s, 12C508As, 12C509As 16F84s, 16F84As, name it and
it'll program it. Except there's one type of chip that refuses to program at
all. That chip is the PIC12F629. I know the 629s are fine because my JDM
"PIC Programmer 2" can program them fine. If I plug one into the Tait
programmer, Vcc stays locked at 1.7V and IC-PROG complains that it can't
read the configuration word. All three test samples have been used
previously, all were configured with their INTRC oscillator turned on with
MCLR disabled. Like I said, the JDM can program them fine.
  The only modification I've made to the PIC interface hardware was to the
PIC socket - I used the socket wiring from the JDM programmer so I could
program SEEPROMs and 12F629s with the programmer.
  Has anyone experienced this sort of problem with 12F629s? All three are
from the same batch and were obtained as samples directly from Microchip.
The chips are marked:
  12F629
  I/PP55
  [M] 0245
(the [M] is the Microchip logo)

Anyone got any ideas? Is it worth buying a few more 12F629s and trying the
programmer with new, straight-out-of-the-box chips?

Thanks.
--
Phil.
philpem@dsl.pipex.com
http://www.philpem.dsl.pipex.com/

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