MCLR causing trouble . .

[Jerson]

I have modified the circuit as it should be. It is remarkable that you can reset your cpu by touching VCC. Please mod the circuit as I've shown and let us know how it goes. The resistors shown are all 100 Ohms.

[mister_e]

Are you using a breadboard??? any chance that there's faulty/loose contact on?

Any chance you have some splitted +/- tracks. mmm maybe a picture would help to explain better
<table><tr><td></td><td>What i mean is that sometime the supply line on some breadboard brands
have a break in the middle of their +/- line.

On the picture, you observe that red and blue line are not continuous,
This said, don't use it as a reference...


What i suggest is just do a continuity test on each breadboard + and - tracks between
each edge (say point 1 and 57).

might be one cause here...</td></tr></table>

PCB and DIP socket? any chance the Vss pin is broken underneath the socket... yeah it happen...

Are you living close to Area 51, Hangar 18?

[shahidali55]

Thanks for the info . . .
I've now got 120 ohm resistors in series with the segment pins.
The buttons are given to a 1K then to GND, internal pullup enebled.
I'm using pref board. Checked for loose contacts. Did find one but that didn't solve the strange reset problem.
The IC is resetting when i just make a light touch on the MCLR pin.
The MCLR pin is given to Vcc through a 10k resistor.
I've got another clock using the very same circuit and it doesn't reset that easy.
Could this be due to ESD ? ? ?

The clock also has a battery backup.
<img src="http://www.delabs-circuits.com/png_circuits/embedded/battery-backup.png">
Pin 3 is used to monitor the mains input. (it is given to the output from the 5v reg ,and not the output of battery backup ,through a voltage divider network).
Could the battery backup be causing a problem ?

[Jerson]

Is your power supply based on a transformer or is it one of those low cost capacitive coupled power supplies? I am suspecting that it is the latter one. Then your talk of ESD makes sense. The best option for you to get any valid answer is to post your entire schematic including the power supply. Without that, all answers will be conjecture.

JF

[shahidali55]

I'm using a SMPS power supply. (from a PC).
Connecting GND to the case of the XTAL solved my problem.
I've never had such a problem before and have no idea why giving GND to case of XTAL solved it . . .
Thank you everyone for helping me out . . .