The PICkit 2 is pretty hard to kill. I would try reloading the firmware as described on page 61 of the operator's guide (link in the article).
Aside from that, the following may be helpful:
1. I have never had reliable operation with the PICkit connected to a hub with more than 4 ports. It will lose connections and behave erratically.
2. Use a powered hub if using a hub.
3. If the PICkit errors, disconnect it from USB, shut down the GUI and start over. This is the only way to reset the self-protection features caused by shorting the power, etc.
I noticed the manual cautions against connecting the PICkit 2 to a self-powered circuit if it's not connected to USB. Makes sense because the output pins would be exposed to greater than Vdd + 0.3 volts.
There were also some engineering changes made to the earliest units. If your PICkit 2 has a black button instead of a red button (and it's a real deal), Google for "black button PICkit 2" and you should find the necessary changes.
Re: PICkit 2 Calibration
6 years 7 months ago #12916
Have you run the test procedure built into the PICkit2 Programmer app? It's under the Tools | Troubleshoot... menu.
That, along with the schematic in Appendix B of the Users Guide should get you pointed in the right direction. If the USB side works, then likely it's a problem with the output transistors/fet switches on page 2 of the schematic.
If you go through the troubleshooting steps and report your findings, perhaps we can help more.
Many thanks for the help . Seems it got worse since i last tried to revive the dead PK2 , now it's not working on USB either, and the 18F2550 not being seen by PK3 ! (I put a connector in J1 to try and burn a bootloader.) could be end of the road ,I could try to remove / replace PIC if i get stuck... Thanks again.