Hello guys,

Quick question. Could these "bubbles" on black blob mean, that IC is cooked? Idk how to test it.

 

I don't think so. It's just the way the encapsulation set.

 

Manufacturing process where die were down bonded to pcb and/or substrate
then a glob was dropped on them to make package impervious to environment
like humidity for example.

Regards, Dana.

 

you test it at all the little holes around it but you need to figure out whats what first. Easier to test pcb input and output functions and then if fault is found work backwards from there imo. The bubbles are probably just how the blob dried.

 

This circuit is tuner in acoustic guitar. I bought it like 5 years ago, I remember that tuner was working just fine in the shop, after that it doesn't. I guess it will be impossible to find what's not working