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iMac G3 Dalmatian Restoration
Posted by: Arkious on 2026-09-05 08:03:52 Hi All, I have been in love with the iMac G3's since my parents bought me one when I was 8 year old. I have longed for a dalmatian and one popped up along with a blueberry for £20 for the set and only 30 mile away! unreal I thought! However, The 600mhz Dalmatian is in terrible condition inside and out having been left in a shed with water dropping into it by looks of it, but unbelievably it still works fine other than its failing flyback. Oddly, the 400mzh blueberry is immaculate inside but is dead, with what I believe to be capacitor failure. Now I have a bit of a unknown direction to take these... since the 400mhz has an LG and the 600mhz a CPT, the LG has a rev 1 board and the CPT has a rev 2 which can do either, but as I say its in terrible but working condition. The sticker on the flyback on the Rev 2 board is unreadable but the Rev 1 is a 6174Z-1017H and looks in decent nick. Will this work in place of the other without knowing which it is? and will the Rev 2 board work with either CRT with the same neck board simply by flipping the switch on the board? Thanks very much!
Posted by: Arkious on 2026-09-11 13:03:24 Well, I spent 2 days cleaning the absolutely destroyed Rev 2 board, swapping over all the heatsinks and replacing a few components that were damaged. I even filed off all the PCB ‘snap’ points so it’s smooth haha. I was then faced with the two flybacks that had differing pins positions, so having checked it wasn’t a multi layer PCB, I drilled the two new holes to suit. Voila! We have life! But unfortunately I have two dead flybacks so still need a new one 🙁
Posted by: Froggy814 on 2026-09-11 14:09:39 That's a good sign! If it is the LG flyback I would love if you could take some continuity measurements for me. Thanks! I have a Blueberry iMac that has a all white screen, so I hope it really is just a capacitor problem!
Posted by: Arkious on 2026-09-12 03:56:54 That's a good sign! If it is the LG flyback I would love if you could take some continuity measurements for me. Thanks! I have a Blueberry iMac that has an all white screen, so I hope it really is just a capacitor problem! I certainly will when I remove it again 🙂 I’m hunting for a replacement at present, which is not so easy without it costing a silly amount by time I pay import taxes 🙁
Posted by: Arkious on 2026-09-12 04:33:51 Whilst I continue my quest to find a FBT, I decided that I need to consider cooling improvements. Now space is significantly constrained and I don’t want to make it look like it’s been butchered either. So I took design cues from the tray loader and added a fan directly central at the convection gap. It’s 2.5mm thick including a 1mm lip on the opposite side to retain it without gluing/screwing. I’m then using a 40mm Noctua fan to force air up through its normal convection path. This should draw air over the back of the logic board improving the CPU cooling, as well as more air within the PAV/CRT area. At only 12mm tall, It’s rated at 8.2m3/h at only 17.9 decibels so should not add any significant noise. I considered adding ducting but will see how it feels when installed. I will run it externally powered and feel for air movement. I am considering adding a second directly to the FBT, but can’t do that until I find the replacement 🥲 see the video for size/noise
Posted by: Froggy814 on 2026-09-12 07:40:45 I certainly will when I remove it again 🙂 I’m hunting for a replacement at present, which is not so easy without it costing a silly amount by time I pay import taxes 🙁 So is the iMac all together? or just the flyback on the board? Because I would like the measurements from the board to see if everything is continueted to the same place as mine... Whilst I continue my quest to find a FBT, I decided that I need to consider cooling improvements. Now space is significantly constrained and I don’t want to make it look like it’s been butchered either. So I took design cues from the tray loader and added a fan directly central at the convection gap. It’s 2.5mm thick including a 1mm lip on the opposite side to retain it without gluing/screwing. I’m then using a 40mm Noctua fan to force air up through its normal convection path. This should draw air over the back of the logic board improving the CPU cooling, as well as more air within the PAV/CRT area. At only 12mm tall, It’s rated at 8.2m3/h at only 17.9 decibels so should not add any significant noise. I considered adding ducting but will see how it feels when installed. I will run it externally powered and feel for air movement. I am considering adding a second directly to the FBT, but can’t do that until I find the replacement 🥲 see the video for size/noise Please let me know how the fans go! That is a smart idea, to cool the parts that fail cause of heat!
Posted by: Arkious on 2026-09-14 22:04:19 So is the iMac all together? or just the flyback on the board? Because I would like the measurements from the board to see if everything is continueted to the same place as mine... Please let me know how the fans go! That is a smart idea, to cool the parts that fail cause of heat! Yeah it’s back together so will stay like that for now until I get a replacement Flyback (just to avoid damage). Let me know what you need testing and I will get it done for you 🙂 Yeah I’m quite happy with it to be fair! Not tested it in situ for air flow but it will physically fit fine. As I say when I get the new flyback I want to create a clip on attachment so that another one can be attached to give it direct airflow from that fan. While away from that though!
Posted by: Froggy814 on 2026-09-16 16:05:35 I marked what is internally connected to GND with red. If there is no continuity between the pins I didn't put a mark. Do you understand? Because I want to make a chart of what it looks like if it is internally shorted, but I need to know whether the flyback is working or not. Thanks! BTW how is the fan?
Posted by: Arkious on 2026-09-20 13:06:29 View attachment 103958 I marked what is internally connected to GND with red. If there is no continuity between the pins I didn't put a mark. Do you understand? Because I want to make a chart of what it looks like if it is internally shorted, but I need to know whether the flyback is working or not. Thanks! BTW how is the fan? Yeah I will do this as soon as I get hold of the new Flyback 🙏🏻
Posted by: Arkious on 2026-09-20 13:12:58 whilst I await getting hold of the flyback, I got hold of a brand new keyboard (in danish) as the keyboards supplied with the Dalmatian were DISGUSTING. Gives you a good idea of what I’ve been dealing with, but it’s coming up extremely well. So basically I’ve just cleaned and polished the black keys and transplanted them to the danish keyboard, and voila I have a brand spanker. It’s slightly different having a white inner rather than aluminium but I kind of prefer it. I plan on pairing it with the white mouse rather than the black, but it too needs a good bit of TLC.
Posted by: Froggy814 on 2026-09-20 13:13:05 👍 Thank you! My iMac seems to be fine. It was the HD, that was causing a all white screen without anything I think. It was locked and doesn't spin!
Posted by: Froggy814 on 2026-09-20 13:13:53 That new one looks a lot nicer to touch!
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