Quote Originally Posted by HenrikOlsson
Keith,
I found the info about the resistor in the file hlpPSPlus.chm in the ...MPLAB IDE\PicStartPlus folder. I tried with only the resistor and it SEEMED to work but I'll try to actually put a real file in it when I get home.
Thanks Henrik, found it now...

PICSTART Plus Limitations for PIC18F2331/2431
All power supply (Vdd and AVdd) and ground (Vss and AVss) pins must be used in order for these devices to program. PICSTART Plus will handle Vdd, Vss and AVss properly, but you must place a 1kOhm resistor between Pin 7 (AVdd) and Pin 11 in the socket with the device for proper operation. There are other devices that may require the use of all power supply and ground pins. Consult the datasheet if an unexplained programming problem occurs, such as inconsistent programming.

In your original mention of the resistor you said "between pin 7 (AVdd) and pin 11 (RC0)". the help file just mentions "Pin 11" rather than "RC0"

Looking at the pinout of the 4431, pin 11 is actually AVdd so I wonder if the resistor is because power is supplied to the wrong pins. Also the help file does not mention problems with the 4431 which also wouldnt program for me

Will experiment tonight.

Quote Originally Posted by acetronic
Hi,Keith

Have a look here :http://www.mbtronics.com/picxx.asp
Thanka Alain but I already have the upgrade fitted.