Chosen Solution
Hi there :) I’ve purchased this laptop from company who repair laptops. Left speaker is “squeaky” like it would have interference (and only when is active) I’ve replaced it with second hand from eBay and still got such a noise - is it possible that something else is broken? Connector looks ok. Can it be something connected with headphone jack or something else. Definitely obvious things like new macOS reinstall - SMC and NVRAM reset did not helped :( Some updates: No liquid damage - all 10 or more stickers are whiteBoth speakers are 100% fine as I swap them and left working one was crackling in right connector.System plays music great on headphones - so my guess audio chip is fine.Squeaky speaker still plays music - but with squeaky background.
When the speakers are making sound when you are not playing something that has a sound is what we call leakage. This could be a low hum to a high pitch squeal. The cause is often related to a bad noise filtering capacitor or liquid damage. What was the warranty on the sale? I would bring it back to get fixed by them. Update (11/26/2018) This will take some work ;-{ You’ll need a set of schematics and board view to locate each one. You’ll also need to work though quite a few caps. I would start around the audio area first, To give you an idea here is the part of the logic board you’ll need to start with
The Yellow marked chip is the DAC and the caps on this side and the other here
Will need to be checked one by one.
