Zener diode going bad on negative supply voltage

[ANMOL]

Dear all,
I have a 4*2030 circuit in which I am experiencing a problem that the Zener on negative voltage stops working or the voltage across appears to be 0 and I have observed in all these cases the op-amp ic 4558 I have used also stops working and if I change all of the 4558 and Zener the circuit starts working fine.
I am unable to find the issue why is only the Zener on the negative side causing the problem.

Anmol Malhotra
Student

 

[abraxalito]

Not at all easy to decode a schematic from a PCB layout. Do you have a schematic?

 

[ANMOL]

Please see i have attached schematic

 

[abraxalito]

What's the transformer (AC voltage, VA) you're using? Also what are the zener diode voltages?

 

[JMFahey]

The PCB states 13+13VAC but of course we don´t know what YOU are using.

And as abraxalito says, we also need Zener Voltage and Dissipation, to know whether they are overheated or not.

For proper answers we need to do some Math, and for that we need numbers 🙂

 

[ANMOL]

I am using 13-0-13 v 2.5 ampere (regulation 10% on full load) transformer and Zener In4742 12v 1Watt