Hi Steve,

thank you for your advice.

I`ve moved my circuit from the ProtoBoard to a PCB (universal one, with isolated holes), reduced the crystal speed to 10 Mhz and now, everything is soldered.
Just the power supply lines are a bit long (I´m using a regulated 5 V Power supply).

I still have problems to make the 16F877-20 and the 16F877A working. I have to touch the PIC with my fingers many, many times to make it working ! ! ! really strange...

I tried to substitute the crystal for a ressonator too... but I got the same problem...

Is there another option rahter than the Tantalum Caps ?

Is this problem related to the Power supply or to the Crystal Speed ? (maybe both ?)

Thanks

Sérgio Pinheiro