MCLR  is +5v, checked with the scope.
 Standard scheme to MCLR:
 Resistor and diode to +5v, capacitor to ground.

 RB3 is on the ground without resistor.

  Thank you.
   Mike.

Mike Harrison wrote:
> Sounds like MCLR is floating.
>
> >   I need your advices, guys.
> >
> >   I have few working 16F874-based boards.
> >   I decided to replace 16F874 by cheaper 16F871
> > as code is about 1K locations.
> > Ordered and received a couple of PIC16F871-I/P
> > $3.6 each from local Microchip folks.
> >   Placed them on the boards, programmed with the
> > same code and the same configuration word, verified.
> >
> >   Now all is working fine, but-t-t start - up time got
> > unacceptable: first 16F871 - 4.4 s, second - 6.3 s.
> >  The same code working with I/O ports and RS-232
> > through ICL-232, the same config word "3FFE",
> > the same boards and  crystals, only PICs are changed
> > and all these resulted in different damned start - up
> > times 4 - 6 seconds. (The time between Power-Up
> > moment and when PIC starts to send repeatedly
> > bytes (250 bytes per second) to PC. I monitor it with
> > a scope.)
> >
> >   With 16F874 on board start - up time is almost
> > imperceptible.
> >   I tried different crystals and resistors with them:
> > the picture is the same.
> >
> > What am I missing?
> > Maybe something simple & obvious?
> > I need your advices, guys.
> >
> > Thank you.
> >  Mike.
> >
> >PS: Locations:
> >h2007 - config word (h3FFE)
> >h2006 - device ID value (h0D21)
> >h2005 - (h3F15) - what is it? Does anybody know?
> >h2004 - (0000)
> >h2000-h2003 - (h3FFF)
>

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