Arthur Brown asked for more information.  I'm afraid I forgot to
mention that this is a PIC programmer for the PIC range, and that I
have used it quite successfully so far on PIC 16F84, and PIC 12C509.
I know the information is scant, but that was my choice.  Sorry.
I was asking about the effects of this apparent defect on programming.

Stuart O'Reilly made an observation that the erasure time for windowed
parts was reduced as a result of the lower Vpp, but otherwise it
worked.  Fascinating!  I think this matches my experience with PIC
12C509-JW, though I had not realised this as the cause.  It was about
the time I switched to a 13V Vpp programmer that my erasure times
suddenly grew.

Bruce Gennette claimed that I was using a multimeter.  I'll admit I
was using a Fluke digital multimeter with a fairly high impedance
input.  But I don't think his point was valid, since the 1k pulldown
resistor would be the lowest impedance in the circuit at the time, and
would be the cause of the current flow through the 100 ohm resistor.

Morgan Olsson said I was perfectly right.  Excellent!  Thanks!

My conclusion is that I should not worry unduly.  For development work
with UV EPROM designs, I should take care to verify.  I should also
program with full Vpp for production EPROM chips.  For work with
EEPROM such as PIC 16F84, it clearly works, and so is probably not a
worry.

Thanks for the replies!

--
James Cameron    mailto:quozl@us.netrek.org     http://quozl.netrek.org/

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