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Post by turbokinetic on May 31, 2018 8:41:47 GMT
Was there a lot of debris in the sump, from the slot liners crumbling and falling into the oil from other places in the motor?
The oil is very clean, there are what I thought were a few pieces of metal in the bottom. I will look at them closer next time I take the dome off.
Cool. Again, thanks so much for keeping us abreast of the troubleshooting / repair efforts. Hope to see it go back together soon with new winding!
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Post by ckfan on May 31, 2018 14:32:15 GMT
Sad to hear of this failure mode, but now we know. That paper sure looks brittle in the pics! Thanks for sharing the updates. I'm a bit embarrassed that I haven't had a good block of time to get my DR3 on R124, but such is life. ckfan Are the windings bad on your DRA2, or are you looking to do so as a sort of prophylaxis? The windings aren’t bad currently. I just figure that if I’m going to repair a leak I might as well open it and rewind it if it’s been open to atmosphere this long.
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Post by coldspaces on Jun 5, 2018 2:10:43 GMT
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Post by turbokinetic on Jun 5, 2018 3:06:17 GMT
Interesting pictures again. It does seem that the winding and copper tubes have suffered some chemical attack.
Could it be possible that there is a pinhole leak in the evaporator; whereby water (from the frost on the evaporator) slowly seeped into the unit? If I'm not mistaken, SO2 runs at a slight vacuum under certain conditions, which could result in a very slow buildup of moisture. Again if I'm not mistaken. The acidic conditions created could explain the black residue on the copper, as well as the embrittlement of the slot liners.
The second picture down really does look like the winding is burned. The inner winding (the one closest to the rotor, mainly obscured by the main winding) appears to have lost its coating, leaving a bare oxidized copper appearance. This in contrast to the main winding closer to the camera.
This damage could be secondary to the failure of the slot liners, though. An earth fault in the winding would have put massive current through the other sections of the winding between the lead wire supplying the current, and the actual fault point.
The black residue is really strange, indeed.
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Post by coldspaces on Jun 5, 2018 3:14:33 GMT
The black crud is normal in these so2 machines. So2 is a dirty refrigerant compared to modern ones. We find black crud in every plugged so2 float. That being said this machine has been open 3 times before me at least so maybe some moisture has gotten in for all I know. I got the piece of paper, suspected paint chip and the metal chip all in a clear cap and ready to take a pic of it. That's when I dropped the phone and the cap flipped over on my far from clean workbench. So I lost the metal piece but by then I could see it was a small piece of copper, probably from the end of a tube. The paint chip is just above the 2. NJ DR3 (23) by
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Post by elec573 on Jun 6, 2018 3:38:46 GMT
Was there ever a consensus on where the black crud comes from? Originaly I thought maybe the Cotten fibers but this one was rewound . Or did they reuse the same oil ?
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Post by birkie on Jun 8, 2018 3:36:19 GMT
Was there ever a consensus on where the black crud comes from? Originaly I thought maybe the Cotten fibers but this one was rewound . Or did they reuse the same oil ? Good point. I recall coldspaces posted an article a while back about oils and SO2. The oil slowly (or fastly, depending on temp) reacts with SO2, resulting in the formation of carbon. There's a good chance that might be it See: monitortop.freeforums.net/post/14839/thread
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Post by joneske on Jun 13, 2018 14:48:27 GMT
It’s always amazing to me how prestine they look when opened up. Question do you try to mimize the open air it receives . Do you have a process you use to keep air to a minimum. To exposed parts ? I did try to have it open for a short time only. Then I put the dome back on with 4 bolts only and purged it with nitrogen. It is setting with a 25 PSI nitrogen charge on it for now. I also ran the AC in the garage to lower the humidity before I opened it. I hope to open it again and look at things closer, then I will vacuum it and put a nitrogen charge in till the windings are ready. This is probably a stupid question, but would it work to vaccuum seal the compressor with something such as a Seal-a-Meal to preserve it while working to have it rewound?
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Post by elec573 on Jun 13, 2018 20:01:25 GMT
I think that’s a good question but I’m guessing it would have to be a really good vacuum. To keep out moisture and air .
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Post by birkie on Jun 14, 2018 3:35:28 GMT
Slight pressurization with nitrogen would be better than a vacuum, due to the fact that mother nature abhors those things. That's why this DR3 is happily sitting in its nitrogen-filled dome while it waits.
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Post by coldspaces on Sept 26, 2018 2:44:14 GMT
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Post by csulaguy on Sept 26, 2018 3:19:06 GMT
Pretty cool. I also love the pictures of the inside, though I wish there were more.
This is probably a dumb question, but what is the evap flipper for specifically?
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Post by coldspaces on Sept 26, 2018 4:16:24 GMT
Pretty cool. I also love the pictures of the inside, though I wish there were more. This is probably a dumb question, but what is the evap flipper for specifically? It's so I can get coil flush to all parts of the inside of the refrigerant parts of the evaporators. Turning them by hand on a bench is not that easy.
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Post by turbokinetic on Sept 26, 2018 4:28:41 GMT
Hey I love your Evaporator Rotisserie!
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Post by coldspaces on Sept 26, 2018 4:31:04 GMT
Hey I love your Evaporator Rotisserie! Glad you like it, I made the bulk of it out of wood so I could change dimensions easier if need be.
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