LC 575 refurb options?

[Arbee]

I can fix the lack of schematics, although if the headphone jack works your problem may not be on the logic board.

 

[ClassicMacintosh]

Appreciate it. Time to take it apart down to the bare plastic and find out where the speakers are connected.

 

[ClassicMacintosh]

Currently at this stage of the disassembly - everything is apart down to the front speakers & shield.



Can anyone help make sense of where to start to troubleshoot this? Don't want to break anything, even though perhaps the connection on the inside is already frayed.

 

[pizzigri]

@Arbee, you don’t happen to have the schematics of the analog board? That’s where the audio amplifiers are located….

 

[Arbee]

I have no analog boards, sorry.

 

[ClassicMacintosh]

@pizzigri @Arbee Appreciate the support! Will have to do it without schematics, and hope we stumble across the fault. Have taken it down to the bare plastics -



Nothing immediately obvious below the bottom shield, apart from being a fair bit less dusty than the rest.



The only obvious thing are these two posts where the speaker wires connect to the AB.




Zooming in, it looks like there's some green material on one of the metal "prongs".



Here's where they connect to on the AB. Guessing a clean with iso and then a quick sanding down would be the way to go?

 

[pizzigri]

The two TDA7052A chips are the audio amplifiers… surely cleaning the contact posts can’t hurt

 

[joshc]

Recapping your AB wouldn't hurt as well, those capacitors are probably way beyond the end of their design life and at least a few of the ones that are near high temperature areas are probably out of spec.