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tha Thanks @Jockelill. I connected a jack and checked with a multimeter, but at boot I don’t measure any voltage difference (I don’t have a headset to test directly) when the chime should play. Instead, I just hear some squeaking noises. As I mentioned earlier, the sound was working fine right...

@finkmac. Got it. Still, I think we’re not usually driven by rational decisions or economic logic. If saving money were the goal, we wouldn’t be buying rusty old junk—we’re driven by passion ;)

This LB is gone, can I save the 8 x 2Mb RAM chips and create a 2MB 72 pins SIMM or a 30 pins SIMM? 2MB is not much, but maybe better than leaving them there. I can't find a PCB GitHub project for this scenario (Yes, I'll remove the CPU)

I found a (terribly) bombed LC475 with a different logic board, but the DFAC-II/ASC is the same. 9338XN, 343S0129-01, vs 48ACF5W, 343S0129-01 (the silent one). I plan to replace the 48ACF5W, 343S0129-01 (second in the list of attachments) with the 9338XN, 343S0129-01 (the first) I need to be...

thanks guys. Does anyone know if there are specifications that can help me find a replacement? Are there compatible flybacks? These original parts are really hard to find. +1 YAPJ ... Yet Another Piece of Junk? And, would this explain the incomplete vertical sync?

> Assuming the "hole" is the place circled in red in the initial photo, how does a short emerge from a part of the flyback where there are no wires? I probably wasn’t very clear before. The “hole” is right here in the pic – it’s at the spot where the arc kicks off and it actually goes through...

Also, there doesn’t seem to be much vertical deflection, as shown in the image below. I can see the bottom of the Mac desktop, and the images change when I drag the mouse downward, so the imaging circuits appear to be fine and the horizontal sync as well. From my limited experience with CRTs...

Thanks for this. The arc is between the flyback and the cage box around it; this is for sure. The line below is to emphasise the cage. I checked again after your remark. You were right, the arc originates from a hole I saw after further inspection. Can an epoxy impede the arc? But the coil is...

Is there any chance of replacing the flyback? Would an epoxy potting compound work to prevent the arcing? Time to say "RIP?"

https://68kmla.org/bb/index.php?threads/monitor-high-resolution-monocrome-mo400-arcing.50747/ my bad apologies I cant delete the post

I triple checked to traces and the four caps C137, C136, C149, and C150, they are fine, no shorts. For what it is worth Tattletech is reporting the existence of the sound manager, but no sound can be heard from the control panel. There is white noise and a soft squeaking sound when using it ...

Too early… I’ve very likely destroyed the DFAC-II. When I powered it up again, it made a nasty screeching sound and showed no sign of activity. I checked the board, and across C136 and C137 I noticed some flux residue that was likely shorting them to ground or across the pads. I cleaned and...

I’ve recapped the logic board. The PSU is fine, the voltage rails are stable, and it works with another LC475. It’s working now, but I still need to wait and run more tests, because one of the two VRAM chips is definitely dead now after running it in here. :( I just hope it’s not killing any...

I've ordered two of them .... it all makes sense to me, thanks

I connected an LC 475 to a High-Resolution Monochrome Monitor MO400, specified for 640×480. https://lowendmac.com/1989/apple-high-resolution-monochrome-monitor/ The monitor produced an image for about 5 seconds, then emitted a loud crackling noise consistent with high-frequency arcing. I...

Yes, it’s the one with the black block and a Molex connector on the end. I read about it here in the forum, where someone mentioned using it. I thought that without an HD and an accelerator, it would be sufficient. The Mean Well RPT-60A is definitely better — for what it worth, it’s also sold...

The battery is "new", meaning a couple of years old, left sitting in a drawer. I will: - use a new button-battery with the silicon insider adapter - do a recal - double test the PSU But the VRAM SIMM are really not working anymore now :( g "I'll be back"

Ok, I got a very nice-looking Performa 475 with a network card, HD, VRAM, RAM — but missing the PSU. I temporarily added a known-good PSU from another LC. The capacitors look fine. I even removed one to check underneath, and it confirmed no visible leakage. A very very nice board! Boot time...

Is this a dead thread? I'm planning to use an HD IDE PSU for a Performa 475. The lack of -5V means I’ll lose LocalTalk support — not a big deal, but not ideal either. My main concern is the power requirements. An HD IDE PSU provides 2A on both +5V and +12V rails. Is that enough for a Performa...

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