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Post by solarmike on Nov 15, 2018 19:00:02 GMT
Your secret is safe with me..... But I believe it as fact.... Thanks
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Post by birkie on Nov 16, 2018 2:02:05 GMT
Another issue which happens, is that copper residue from the lines and evaporator and windings can become dissolved in the oil and refrigerant. This will deposit in areas of high temperature and metal-on-metal contact. When the compressor was running under extreme stress due to the NCG's, it may have built up excess copper plating in the rotor chamber. Once the high temperatures and metal-on-metal contact were relieved, the copper plating can wear down; allowing some reasonable running clearances to be established. Hey, that triggered a distant memory. There were a couple threads by don that were notable in that they showed some copper deposition in a dismantled CA, and cited some literature. Take a look at the pics in this thread: monitortop.freeforums.net/post/11779/threadThen a thread specifically about copper deposits in the CA: monitortop.freeforums.net/thread/868/lard-oil-copper-platingIt cites a neat youtube video, and a satisfyingly in-depth article that suggests that contamination by air and oil contaminants are the ultimate cause of the initial corrosion that leads to a chain of events that lead to copper deposits. Interestingly, this seems to be one of the few areas where SO2 is beneficial in protecting against such deposits! Anyway, re-reading those threads in light of this one makes me wonder how widespread copper deposits are in those CAs that suffered from bad NCGs; especially if those NCGs came from air making its way into the system under vacuum.
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Post by turbokinetic on Nov 16, 2018 3:11:53 GMT
Hey, that triggered a distant memory. There were a couple threads by don that were notable in that they showed some copper deposition in a dismantled CA, and cited some literature. Take a look at the pics in this thread: monitortop.freeforums.net/post/11779/threadThen a thread specifically about copper deposits in the CA: monitortop.freeforums.net/thread/868/lard-oil-copper-platingIt cites a neat youtube video, and a satisfyingly in-depth article that suggests that contamination by air and oil contaminants are the ultimate cause of the initial corrosion that leads to a chain of events that lead to copper deposits. Interestingly, this seems to be one of the few areas where SO2 is beneficial in protecting against such deposits! Anyway, re-reading those threads in light of this one makes me wonder how widespread copper deposits are in those CAs that suffered from bad NCGs; especially if those NCGs came from air making its way into the system under vacuum.
Very good articles, thanks for the links!
I particularly enjoyed the scientific article on the chemistry of copper plating. It supports what we all have learned from anecdotal evidence. That a clean, dry, air-free system will minimize this effect. It also is interesting about the chelating agents to remove the copper from the oil and refrigerant. Will need to see if there are any dryers available which include this.
This CA, I doubt has a leak which allowed air to get in. If it leaked air in; then I would have expected it to have leaked OUT the NCG's, oil, or refrigerant during the decades it was out of service. But, anything is possible. There could have been a chunk of bacon left in the hog lard oil additive, which blocked the leak point from the inside, like a check valve flapper, and only allowed inward leakage but not outward!
I have a burned out CA. It was murdered. Someone removed the control (and therefore the overload breaker) and twisted the wires together. They then energized the compressor. Either it never started, or it started and seized while running. Regardless, it drew high current for long enough to burn the magnet wire enamel from the start relay coil winding. In light of this damage, I measured the resistance of the motor, and found it to be much lower than that of the other two CA's I have on hand. I did energize the motor, with a test cord and clip leads, and the clip lead jumper wire was blown in half. This makes me think the motor is dead-short. Before throwing in the towel on this one, I plan to remove the wiring from it and measure at the motor terminals.. but the prognosis is very grim.
I plan to cut it open eventually, to see the condition it's in. During the deconstruction process, my goal is to leave it in a condition where, if desired, it could be re-assembled. That will be a learning experience to see if possible / how difficult it is to cut one of these apart and leave it in a state to be reassembled.
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Post by turbokinetic on Nov 20, 2018 3:15:30 GMT
So, today I made a new coil for the burned out start relay from the destroyed CA-2-B16; and installed it on this CA which was missing a relay.
The only magnet wire I had was smaller, so I made a two-strand parallel winding. It still has the same original 75 wraps of wire. The winding and the paper spool piece are all Class F insulation system materials, good to more than 390°F.... so this coil should not burn out!
Some video of the relay: youtu.be/0qNh3oYrJxE
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Post by ckfan on Nov 20, 2018 13:22:25 GMT
Wow, I never would have thought to rewind a coil like that. It’s so simple though! Very nice work. One thing that is semi related that I have a question about. When you go to clean contacts in these things, what do you use? I’ve heard of using files and burnishing strips. What do you use?
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Post by turbokinetic on Nov 20, 2018 14:49:22 GMT
Wow, I never would have thought to rewind a coil like that. It’s so simple though! Very nice work. One thing that is semi related that I have a question about. When you go to clean contacts in these things, what do you use? I’ve heard of using files and burnishing strips. What do you use? Hi Ray. Yeah the coil was really easy to make. The harder part (yet still not really difficult) was making the little paper spool piece. It was time consuming since I had to make several patterns before finding one which fit just right, then cut the real one out of Nomex. The materials were all ordered from eBay last year for another project. The actual wire was from a coil that I made for a motor, but it was too small. Learning curve. So I unwound it and reused the wire for this project.
I have rewound relays before, but on those the coil bobbin was still usable. Those were rewound to change the current levels that trigger the relay, not because of a burned coil. This was the first time I had to make the whole coil from scratch.
As for the contacts, they sell miniature files for ignition points in an engine distributor. Even though points-type ignition is part of a bygone era, the tiny little files are useful and they still sell them.
I really don't think you need to have a highly polished surface. Just so long as the points are somewhat shaped properly it's fine. Normally, burnishing strips are used on points that are coated with thin layers of precious metals. They remove excess oxide layers, without sanding away the precious metals.
Start relay contacts are usually in very rough shape, where it's going to take an actual file to re-shape them. Or it has in my experience. Maybe because I end up with the saddest oldest scrap iron to work with.
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Post by ckfan on Nov 20, 2018 17:19:20 GMT
That all makes sense. I’ll have to see if I can pick up a good old set of ignition points files. Reminds me of doing that job on my dads 53 Chevy truck.
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Post by birkie on Nov 20, 2018 22:46:10 GMT
Very nice, I'm glad it worked! The paper spool is very clever. It's funny how the tone (in the manual) regarding relays changed. From "its function is obvious and it is easy to get to. Have fun" for the DRs, to "the relays are calibrated with expensive machinery. Don't even look at them wrong" for the CKs. Paraphrasing, of course . Glad the CA relay was a fun one
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Post by ckfan on Nov 20, 2018 23:33:34 GMT
Yeah, I noticed that too. I wonder why they got bent out of shape later on? Maybe because the relay is more delicate? Not sure.
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Post by birkie on Nov 21, 2018 2:52:41 GMT
I wonder why they got bent out of shape later on? Do you mean the armatures, or the authors of the scotch yoke manual
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Post by turbokinetic on Nov 21, 2018 5:00:23 GMT
I wonder why they got bent out of shape later on? Do you mean the armatures, or the authors of the scotch yoke manual
I have a pretty good idea I know why. The early ones were just a start-relay, which either worked, or failed in one of two ways - not closing or not opening. Both of these failure modes were self evident and immediate - and easy to fix.
The later ones, included the motor's overload protective device. If they were improperly assembled, the result could be a very expensive motor burnout, which GE might suffer warranty liability for.
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Post by turbokinetic on Nov 21, 2018 6:05:47 GMT
Got a little cleanup done today.
After using Dad's Paint Remover. Worked very well, but still required some manual mechanical paint removal at the very end.
Some Rust-Oleum rusted metal primer went on. It will support a top coat of white appliance paint.
Also cleaned up the control (borrowed from the un-charged CA top I have) and the control faceplate.
See me play with toxic sludge!
youtu.be/72Ilj0gC3xw
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Post by Travis on Nov 21, 2018 14:35:03 GMT
Just don't eat it, like the children do!
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Post by turbokinetic on Nov 21, 2018 15:54:03 GMT
Just don't eat it, like the children do! But it looks so TASTY!
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Post by birkie on Nov 23, 2018 3:51:02 GMT
That stripper was sure effective! Looking at the MSDS, it's mostly methylene chloride, with a few added alcohols. Interestingly, methylene chloride itself is apparently not an outstanding stripper in and of itself, despite penetrating easily in the paint. It's the other chemicals that come along for the ride that end up swelling and delaminating the paint. The methylene chloride just blazes the trail. So it is good to have found a winning combination for the paints and primer on the CAs.
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