Odd issue, hardware or MCLR

[jpeakall]

Hi All,

I have an odd one here. On a PCB I made myself, I had a little project working. It's a nixie clock, with '595 shift registers. Everything was working fine, then the nixies stopped working correctly and the PIC16F88 wouldn't program. I am using ICP.

Buncha troubleshooting later, I discover this odd fact: With 5V on the MCLR pin, the sucker won't drive the nixie correctly. With 2.5V on the MCLR pin, it will. It has the standard pullup on MCLR, 10K and if I put a 10k pulldown (making a voltage divider) resulting in 2.5V being on MCLR it works.

What the heck?

Jonathan

[ScaleRobotics]

What are your configs set to? With LVP (low voltage programming) set to ON, it will behave badly at 5v. If it is on, set it to off.

[jpeakall]

Well, the LVP bits *should* be set correctly. But now the programmer won't program chips in the ZIF socket either. This is the third time a MELABS programmer has crapped out on me. I'm getting the "Target device doesn't match" error. I'm getting the right voltages on J3 and tried it on two computers. Grrr.

Jonathan