68kMLA Classic Interface

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PowerMac/Performa 5xxx NOS tube swaps directly into slot load iMac G3
Posted by: Trekintosh on 2026-02-22 15:45:02 This is an informational post to confirm for any hopeful future googlers that the tube from a Power Macintosh/Performa 5xxx series swaps directly into a slot loading iMac G3 (at least my early 400mhz DV) with no issues. There’s a dynamic purity/moire coil on the iMac tube that doesn’t exist on the 5xxx tube, but the analog board doesn’t seem to mind. This means the 5xxx tube will swap directly to a Molar Mac or tray loader, too. What I don’t know is if the Chungawa or LG tubes from a slot loading iMac will work properly without that purity coil connected. I’d imagine it should be fine, I just can’t confirm or deny it. The final two pictures are my after and before, in that order. The before (the open firmware picture) actually looks sharper on my phone than it does in real life. The tube I replaced was cooked. Yes, I adjusted the focus. It was just tired. The new tube is so sharp I could weep, I’m running into the limits of the dot triads, not the beam focus. (This has been cross posted to all the major Mac forums to maximize the chance of searchers finding useful info)
Posted by: obsolete on 2026-02-23 09:41:00 Wow! Dare I ask where you got the 5xxx CRT and how much you paid for it?
Posted by: Trekintosh on 2026-02-23 11:22:46 Wow! Dare I ask where you got the 5xxx CRT and how much you paid for it? Actually got it on eBay for about a hunge shipped. Screamin’ deal, all things considered. Also have a NOS analog board for the 5400, too. When I finally got around to testing the 5400 I have it turns out the tube is basically brand new tier already, and Techknight informed me that the new tube would probably fit in my iMac, so I decided to confirm that.
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