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LC 575 refurb options?
- Thread starter ClassicMacintosh
- Start date
Appreciate it. Time to take it apart down to the bare plastic and find out where the speakers are connected.
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.
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 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?
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?
OK, so thanks again to all - cleaning up the posts on the AB and removing the gunk from the connectors did the trick.
@joshc Everything appears to work, however now on power-on there appears to be a hissing/whining, almost sounds like a kettle. Sounds like it's coming from the back, near the flyback, or even where the AB connects to the back of the CRT. It only appears to be producing this sound when the crt powers up (after the sound of the initial static). Couldn't isolate it to the speakers - could it be related to the caps, as you mentioned? Have checked all connections.
@joshc Everything appears to work, however now on power-on there appears to be a hissing/whining, almost sounds like a kettle. Sounds like it's coming from the back, near the flyback, or even where the AB connects to the back of the CRT. It only appears to be producing this sound when the crt powers up (after the sound of the initial static). Couldn't isolate it to the speakers - could it be related to the caps, as you mentioned? Have checked all connections.
@ClassicMacintosh That's a classic symptom of "corona discharge", the high voltage finding a path to ground somewhere. It's often due to dirt/dust or cracked insulation on wires. Worst case, it can be due to the insulation inside the flyback transformer breaking down, in which case you're unfortunately on borrowed time. Try powering the machine up in a dark room with the screen brightness turned down and look for kind of a blue/purple glow to track down where it is.
That doesn't sound ideal. Alright, will power it on in a dark room - could it be due to the shielding below the AB (which was pretty rusty, & bent out of shape a little when reinstalling it)?
Alternatively, can a 580CD AB + CRT fit in the same spot? Got one that the case exploded into showers of brittle plastic, but the insides survived.
Alternatively, can a 580CD AB + CRT fit in the same spot? Got one that the case exploded into showers of brittle plastic, but the insides survived.
Yeah, if you look at it and go 'oh, that's a really pretty purple', it's probably corona discharge which isn't a good sign unfortunately...
