PIC stop responding - Strange Problem!

[Jerson]

The leds are shown the wrong way. If this is how you have them connected, they will not light up. But, this is a minor issue

Check your power supply. Remove the PIC and force both relays to on via jumpers. In this condition, what is the supply voltage to the input/output of the 78L05? Is the PIC Vdd being satisfied?

You do not have a decoupling cap across the PIC Vdd-Vss.

[Acetronics2]

Hi,

+1 for Jerson ...

AND, once more

Do not forget the .1or .22 µF cer capacitor as close as possible to the power pins ( 1-8 ) s

a 10µF tantalum at the 78L05 output won't be too much nor ...

instead of the Diode across relay coil terminals, a series RC really goes fine ... but some scope necessary to tune the values ... leaves the power lines much cleaner !

Alain

[financecatalyst]

The leds are shown the wrong way. If this is how you have them connected, they will not light up. But, this is a minor issue

Check your power supply. Remove the PIC and force both relays to on via jumpers. In this condition, what is the supply voltage to the input/output of the 78L05? Is the PIC Vdd being satisfied?

You do not have a decoupling cap across the PIC Vdd-Vss.

Thanks for thr reply Jerson. After I switch all 4 relays on, 78L05 input/output is left with 10.9V, still having 5V for PIC.

Should I increase the resistance for the LEDs as well?

[aratti]

Tray adding the two capacitors and one diode as per the attached schematics.

It should cure the problem.

Al.