From: "Vasile Surducan" <piclist9@gmail.com>
> David Corrigan wrote:
> > I bought the EasyProg kit from embedinc (http://www.embedinc.com/EasyProg/)
> > and had it working for a short time. Right now the Vpp pin is stuck at 10
> > volts. (I checked all the lines with pic_ctrl) Does anyone know specific
> > traces on the programmer that could cause this?
> 
> http://www.embedinc.com/EasyProg/prog7.pdf
> 
> Unfortunately this is a very good example about how simple things
> could be done amazing complicated. For example generating the Vpp
> from a 17V line with dozens of transistors, OA and so on, when 13.5V
> is already on the board near another chip. Guess which one ?

Do you have the faintest idea what you are talking about?

I see 1/2 of a quad opamp, three transistors, two diodes and eight
resistors, which together provide two separate voltage-regulated and
current-limted Vpp supplies with individual logic-level enables. Can
you honestly do better, while meeting the same specs for flexibility
of control, accuracy, protection and component count?

Where do you see 13.5 V anywhere in the design?

Anyway, to help the OP, if you can see the PIC outputs switching
(pins 10 and 11), but the Vpp output(s) are stuck on, then either
the opamp or one of the transistors is damaged. One of the 430-ohm
resistors (R8, R9) could be open as well, but this is unlikely.

-- Dave Tweed
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