If the symbol of Texas is upside down then it is a Chinese copy.

It is very kind of the fakists to make their work so readily identifiable.

 

A new Chinese grocery store opened. It was selling LAMP meat because a "b" is a "p" that is upside down. LAMP chops.

 

A new Chinese grocery store opened. It was selling LAMP meat because a "b" is a "p" that is upside down. LAMP chops.

https://www.alibaba.com/showroom/lamp-meat.html

 

I did not know that Chinese food stores use a pink lamp to make rotten meat look fresh. Then they call it LAMP meat.
Do they call DOG meat GOD meat?

 

Hello,

Do you have decoupling capacitors on the boards fitted?

Bertus

I tried 10 mfd and 100nF decoupling capacitor. Problem persists.

 

(A lot of text removed for clarity) Once I replace the opamp, then every thing will be fine. This is happening only in some of the boards.

That strongly suggests either a defective opamp or a soldering problem. One can imagine a bad batch of opamps or perhaps more likely damage such as ESD damage when handling the opamps or loading onto a PC assembly.

It may be worth examining the handling of the opamps and circuit boards during stocking and manufacturing and to replace the opamps in finished goods inventory before shipment.

 

Hello,

I tried 10 mfd and 100nF decoupling capacitor. Problem persists.

Can you post a schematic complete with all decoupling capacitors?
I would expect a 10uF on the power entrance of the board between +supply and 0V and between -supply and 0V.
Also the 0.1 uF at each opamp between +supply and 0V and -supply and 0V.

Bertus