Seem to remember similar recent posts about this problem - either on this forum or Microchip or Et.
Have you got mclr pulled up with 10k.
Also worth putting RB3 / LV PGM to 0v - see the datasheet section - Low-Voltage ICSP Programming.
As mentioned in many forum posts you are pushing your luck with the JDM programmer - really suggest you look at the Pickit2 - worth every dollar - or if you want to - its quite easy to build a simple cut down, programmer only, version of it - as long as you can do the initial programming of the 18f2550 chip.
Thanks for ur reply.
I have Pickit2 Programmer and i am using pickit2 for 1 year.
But this JDM is problematic in my older board but i am in a situation to rectify that problem.
I pulled up the MCLR pin with 1k resistor and I grounded the RB3/PGM pin as well.
Please upload the schematic of the JDM that you tried to use. Generally most JDMs use high voltage for programming. If so, there is no need to ground Pgm pin.
I would suggest you make one external powered Programmer like the design by DL4YHF
In case you are trying to program keepinyt in the target bord, without disconnecting other links, there might be some issues. you need to isolate connections on RB6, RB7,Mclr, and RB3
the best us is to use pickit2 compatible, like JUNEBUG from www.blueroomelectronics.com or PICKIT2 clone from www.mcuhobby.com .
perhaps you may purchase a simple PIC Cruizer programmer from www.united77.com
Hai Sukumar
Just go for this pocket size PICkit2 compatible PIC programmer with USB port support from United7 technologies. Just costs 1500/- for complete assembled tested kit with a programming board, programming software and manuals on CD icluding postage anywhere in India. For more info visit
Finally its working. I replaced 1K with 10K(thanks wp100) and Tied PGM to ground. Replaced Series resistor with MCLR pin with pullup resistor. And finally it is working.
Hai Sukumar,
Thanks for the nice words abt the PIC Cruizer. In case you decide to go for it, and you are from Bangalore, It is availble in Bangalore at the below mentioned address:
M/s Sunrise Electronics,
No 67, Karthik plaza,
S.P. Raod, Bangalore-2
Ph: 080 41243027