Hydra Cooking L78L33s?

[Pauleo1214]

Hi everyone! On one of my past builds, the Hydra keeps cooking L78L33s. All resistor values and capacitor values are correct. There are no cold joints or bridges either. I've tried with both TL072s and JRC4588s and get the same results. No delay signal, only the dry signal. R7 and R16 don't show any resistance (both are 10K). These resistors read 1.16k on my hydras that are working.

I'm pretty baffled and since there is no schematic, lost. I read some other threads about the L78L33 getting cooked on other FV1 builds but nothing conclusive or common among the threads posted. Does anybody have any idea what might be causing the issue?

Best,

Paul

 

[DGWVI]

 

[Sturdag Lagernathy]

I'd look for shorts around the switches on the 3.3vdc rail. A short will kill those little regulators quick!

 

[Pauleo1214]

I'd look for shorts around the switches on the 3.3vdc rail. A short will kill those little regulators quick!

Nothing there unfortunately. Leads were cut nice and low before I soldered the switches in. They're housed in plastic to boot.

 

[fig]

What's the current draw? I think they are rated for 100mA....

 

[Pauleo1214]

Dunno if this applies but 0. Now it's reading 0 volts across the board. I hate to say it but it's time to scrap this board.

 

[KR Sound]

How about some pics? Maybe we can spot something.

 

[Pauleo1214]

How about some pics? Maybe we can spot something.

Thanks for that. I already pulled the pots and some other components in preparation for a new one.