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G4 Cube Power Supply Repair
Posted by: beachycove on 2011-11-25 20:38:52 Anyone on here have a failed Cube PS? I have just repaired mine. The "hairdryer fix" which I reported on some time ago suggested that I had capacitor trouble, and this led me to open the supply up and not just renew the solder joints, but replace the offending capacitor with a new one (C6, 35v, 220µF; I replaced it with a 50v, 220µF one for a little additional insurance). The disassembly of the PS is the troublesome part. Some suggest cracking the end cap, which is held in place by a little tab either side of the plug/ power line at each end. The tabs are located roughly in line with the beginning of the edge bend, in between the end cap and the inner metal case. I did not want to break the little plastic tabs, so instead I used a small handsaw to cut a 2cm nick in the plastic casing about 1cm in from the end on the rounded edge, thus making a hole just big enough to get the blade of a small pocket knife down between the plastic cap and the metal case inside. The blade is then easily leveraged, and thus the tab is easily depressed, so that the thing comes apart. Plastics removed, you then have the inner metal case to disassemble, which is begun by removing the four screws that you see, followed by prying off one of the ends, and then shoving a long, thick screwdriver down each side at the joint, which has the effect of releasing the metal tabs holding the thing together. A sturdy pen or a hardwood dowel (8" long or so) would likely have the same effect. It took me a while to figure out how to do this best, but this method works very well and does not so much as bend the metal. Once the "clamshell" inner case is apart, you discover that there are two copper plates in the way, glued together but with three points requiring simple desoldering, one on the first you encounter and then two underneath on the second plate. Do not use too much force; the layers are glued, as well as soldered as described, and you have to take them one at a time. I am not sure what they are for, but they must be removed in order to expose the innards, which allows replacement of the troublesome capacitor. Repair the capacitor, resolder the plates back in place, test with your Cube (not touching a thing in the PS, obviously), and then, assuming all is well (your Cube boots), reassemble the whole unit. Reassembly is fast and simple. QED. The cosmetic damage is slender, the thing goes together again and stays together without the need to glue on the end cap, and the sawcut can be filled with anything from plastic wood to ordinary caulking to matching plastic paste from plastic crumbs/ shavings dissolved in acetone.
Posted by: mondrage on 2021-10-01 15:50:47 Sorry for reviving an old thread. Mine just died on me. How did you arrive at the C6 capacitor? do you have a schematic? is that the C6 by the transformer? Thank you
Posted by: mg.man on 2021-10-02 00:39:28 You might want to check this out... - Post in thread 'Modern G4 Cube PSU replacement?' https://68kmla.org/bb/index.php?threads/modern-g4-cube-psu-replacement.37271/post-421871 Haven't tried one myself, but I'm in the market for one... two Cubes, 1 PSU atm... 😞
Posted by: beachycove on 2021-10-02 05:34:17 As that was ten years ago, I can’t remember the details, but I think I would have used a “how to” from this, that or the other Cube website. As for the question of capacitors, at this stage I might think about doing a complete recap rather than just hunt for C6.
Posted by: mondrage on 2021-10-02 07:19:47 Thank you both. I bought a 200W from AliExpress. And it’s small enough to fit inside the cube. but I still wanted to rescue the darn thing. besides. I still have two cubes. I think I’ll buy a mini DIN power connector and see what happens. but, it might be better to gut the thing. It was very inefficient to begin with.
Posted by: mg.man on 2021-10-02 07:48:50 Check the other thread... that "DIN" connector is not a common variety... there was quite a bit of discussion over there - you might want to go back to the top and review... Good Luck!
Posted by: mondrage on 2021-10-26 11:02:36 got the power supply from Ali Express. I think they sent me the 400W version, but very likely just the advertised 230W. More than enough. It's smaller than the apple PSU. (https://www.aliexpress.com/item/32839935570.html?spm=a2g0s.9042311.0.0.2e424c4dOEAr77) The problem is that it doesn't come with any manuals, and the input 120-240VAC terminals are not labeled... I'll probably make a video.
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