Hi y'all,
    Fixed it ! The problem was caused by a 100nF decoup cap across the +5V
to gnd. Cap in -> no program, Cap out -> program!
I have had this in for many other projects (usually '877 or '876) without
any problems but I guess the line on the PS+ driving the +5v  for the '628
just hasn't got what it takes. The logic analyser indicated the timing was
right but I guess it's trip level and that required by the 628 were not the
same.

Anyway it is just something to watch out for when using a PS+ to "ICSP"
program a '628. (I know - the PS+ is not meant for ICSP - but I have had no
problems until now because I keep my lines very short ~1-2cm).

John

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