you're the solder expert, I'll believe itlooks like solder residue.
On my L30 (not broken), volpot shaft and RCA shield is electrically disconnected.Parts can fail without it showing on the outside.
My hunch is the OPA is at fault.
Did you find what was rattling inside ?
I read somewhere it may have been metal coming from one of the rear screws.
When you have a multimeter I am interested in the following thing:
Is the volknob made of metal ?
Does the volpot shaft make electrical contact with the RCA shield ?
Yes, looked like it.
The next question is whether or not the volknob is made of metal.
The rattling comes from the earbud not the L30. After doing the ESD tests and when I played music again with the earbuds attached to the L30, the right earbud got really hot. Later on I noticed that somehow a part inside the earbud must have gotten loose, because it rattles when you shake it.Parts can fail without it showing on the outside.
My hunch is the OPA is at fault.
Did you find what was rattling inside ?
I read somewhere it may have been metal coming from one of the rear screws.
When you have a multimeter I am interested in the following thing:
Is the volknob made of metal ?
Does the volpot shaft make electrical contact with the RCA shield ?
View attachment 105563
what's this silver-colored spot on @artburda 's photo?
My L30 board has no solder on that point.
Might be a blown trace. There's one running there to the suspect opamp.View attachment 105565
this is what my board looks like.
View attachment 105564
on my L30 (not broken), knob seems to be partly metallic, but its surface is coated so it's not conductive.
The attachment at the center grabs the D shaft and insulates it at the same time.
That trace appears to go to the dc detection circuit. So if its blowing that might explain why the amp isnt shutting down when the output shorts.