IR21884S Question

I have an amp here all of the outputs test fine out of circuit .

I tested the IR21844S driver ic’s and notice one is shorted .

Has anyone ever seen this were the ic goes bad but all outputs test fine ?

No work has ever been done on the amp prior to me getting it .
it is theoretically impossible for this to happen, so I advise you to double check on the mosfets.
When an IC breaks, the first to suffer are the output mosfets and vice versa.
When such a thing happens, very often the other ICs also break, causing a catastrophic failure of the entire audio stage.
If the protections are efficient enough, the power supply will be saved, otherwise even that one will break.
If you are lucky that the problem is isolated only to one of the amplification stages, you may still have to replace all the mosfets and all the ICs.
 
Any semiconductor can have a random failure. It may happen more often than we realize. When an amp fails and it comes in with blown outputs and drivers, who can say for certain which failed first? The failure of either can cause the failure of the other.
Holy words!!!
Last night I delivered an amplifier to my client.
Amplifier perfectly repaired, 100% working.
He just connected it to the test bench, he just phoned me and told me that the amp remains in protection.
Absurd things in life.
 
Testing MOSFETs with simple MM won't tell what is the health of the mosfets. Using transistor tester, which can show up Rds and all of the other specs helps a lot. Matching MOSFETS also minimizes the risk of future failures.

Two months ago I've repaired Ground Zero GZPA 1.10000SPL...output section - everything new, driver board refreshed, mosfets matched, new resistors...everything...2-3 days of work were put in this monster.

Two-three days later the client gives me a call back...amp has blew up again. Annnd it happened when he was listening it at a really low volume....go figure it out now...and it's not a cheap repair.....
 
You have to pick the amplifiers and customers that are likely to give the most profitability. Some techs want to repair the big amps to show how good they are. Well, the big amps sometimes have intermittent problems that are difficult to find (intermittently shorted inductors is a real problem). If you want to be profitable, you may have to expand the equipment that you repair (not just car amps) and may have to be selective on the make/models you will take in. I never had a problem telling someone that I didn't work on a particular amp because it was badly designed. For some, I worked out what was making them unreliable and didn't have further problems.

For some customer bases, you just have to bite the bullet and repair it for free or risk being threatened/having your shop damaged.