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Post by scooter76 on Sept 3, 2019 15:51:00 GMT
Well, folks, I'm heartbroken. After running beautifully for nearly a month now, I noticed this morning that I hadn't heard the DR-2E kick-in in a while (not unusual, as infrequently as it runs). I opened the cabinet and was greeted with an ominous puddle of warm water and then noted that the overload had tripped. Hmmm...not a good sign. I then began tracking-down the source of the problem and found two things amiss - the first thing I noticed was that the heater was open. Other than it being the original heater to the machine, no biggie. I have several modern cartridge heater replacements. I thought obviously its failure must simply be coincidental to whatever else went wrong and continued troubleshooting. I was sick to my stomach to discover that the start winding is suddenly dead shorted to common. Still 3.2 ohms from run winding to common, but 0.2 between common and start. I can only surmise that one of a couple different scenarios caused it. One could be that the insulation between windings just finally failed after 90 years - certainly possible. The other more concerning possibility is that the 100uf / 450V capacitor that I had been running in place of the failed vitreous porcelain start resistor is simply not a wise choice - maybe the surge it provides at startup was too much for the winding to handle over time and it eventually arced and welded internally? Third possibility is that the undetected heater failure (the machine is in my shop and ran unattended for about the last week or so when we took a trip to our cabin) caused a lubrication upset, the compressor got tight again, stalled on startup, and caused an already old and compromised winding to short out before the overload had time to trip. Or perhaps a combination off some or all these factors. Either way, sadly, I think it's a goner. The early Seeger-built porcelain cabinet is nearly minty, so I guess I'm now on the prowl for a period-correct "tall-control" pig-evap DR-2 refrigerating unit and I'll start all over. What a bummer...
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Post by turbokinetic on Sept 3, 2019 16:13:14 GMT
Well, folks, I'm heartbroken. After running beautifully for nearly a month now, I noticed this morning that I hadn't heard the DR-2E kick-in in a while (not unusual, as infrequently as it runs). I opened the cabinet and was greeted with an ominous puddle of warm water and then noted that the overload had tripped. Hmmm...not a good sign. I then began tracking-down the source of the problem and found two things amiss - the first thing I noticed was that the heater was open. Other than it being the original heater to the machine, no biggie. I have several modern cartridge heater replacements. I thought obviously its failure must simply be coincidental to whatever else went wrong and continued troubleshooting. I was sick to my stomach to discover that the start winding is suddenly dead shorted to common. Still 3.2 ohms from run winding to common, but 0.2 between common and start. I can only surmise that one of a couple different scenarios caused it. One could be that the insulation between windings just finally failed after 90 years - certainly possible. The other more concerning possibility is that the 100uf / 450V capacitor that I had been running in place of the failed vitreous porcelain start resistor is simply not a wise choice - maybe the surge it provides at startup was too much for the winding to handle over time and it eventually arced and welded internally? Third possibility is that the undetected heater failure (the machine is in my shop and ran unattended for about the last week or so when we took a trip to our cabin) caused a lubrication upset, the compressor got tight again, stalled on startup, and caused an already old and compromised winding to short out before the overload had time to trip. Or perhaps a combination off some or all these factors. Either way, sadly, I think it's a goner. The early Seeger-built porcelain cabinet is nearly minty, so I guess I'm now on the prowl for a period-correct "tall-control" pig-evap DR-2 refrigerating unit and I'll start all over. What a bummer... I'm so sorry to hear this happened to you after getting it running so well. I wouldn't feel as if it's your fault though. This seems to be the normal failure scenario for these. It seems the windings wear from vibration and deteriorate from SO2 over time. The fact that it was ever stuck means that there was some sort of corrosion or other problem. You never know until you put them on the road, so to speak. So, I don't think the capacitor was a factor. Often, the winding will short to ground from vibration wear. If two points ground out, it's a short which will create the problem you're seeing. Hopefully you will be able to find a replacement for it without too much hassle.
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Post by coldspaces on Sept 3, 2019 17:53:53 GMT
Sorry to hear this. It was most likely age and that the windings had been over heated when it was stuck. The I seized DR I freed a few years back didn't last long.
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Post by birkie on Sept 4, 2019 1:56:08 GMT
Sorry to hear that! Where approximately are you located? Maybe someone can help you find a unit.
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Post by scooter76 on Sept 4, 2019 19:24:02 GMT
Hi - I'm in Janesville, WI. About 40 minutes south of Madison and 1.5 hours north of Chicago. Any leads on a clean unit would be awesome. Ideally, I'd like an early DR2 unit with a pig evap, so that it is reasonably period correct for the early cabinet. Thanks for keeping your eyes peeled!
Ryan
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Post by turbokinetic on Sept 5, 2019 12:41:08 GMT
I have a "theory" about why these may become stuck and develop ground faults etc. It's fairly long so bear with me.... and it's only a "theory" so I could be completely wrong.
The theory is, the motor damage happened first, and lead to the stuck compressor.
How? This is where it gets fairly long. The windings are insulated with cotton, and separated by paper. These are cellulose based materials. One interesting property of these materials is that they undergo chemical breakdown well before they reach a melting point. Because of that, if the motor is severely overheated (as in stalled and energized, or start-circuit is constantly energized) the paper and cotton materials can be partially degraded without completely failing. If the overload has been tampered with in the past, or repeatedly reset without letting the motor cool, the winding could reach a temperature where the cotton and paper materials begin to break down. Two of the resulting compounds are char (carbon containing solids) and water vapor.
In looking at a severely burned CA compressor motor, it was apparent that the cotton had completely charred but was still mostly in place. It was extremely brittle and came off when touched. Before opening this compressor, the electrical resistances were not too far out of line for this motor; and the unit would initially hum and draw somewhat reasonable current for a stalled motor.
The second observation was the destructive test of a Westinghouse motor with both start and run engaged at once. That motor continued to function, without solidly short-circuiting, until it had been on fire for several minutes.
So it is apparent the winding materials can undergo significant chemical changes without immediate electrical failure.
My theory is that the controls went bad in some way. The control failure its self (or misguided troubleshooting attempts), allowed the motor to remain energized stalled, or have its start-winding stay engaged while running. This would result in overheating, with partial breakdown of the winding insulation. The contaminants being released into the system would include water and other gases. The water will immediately react with SO2 and form a corrosive solution. This could then cause sticking of the compressor whenever it is allowed to sit without running. The charred winding materials would also be very brittle (and possibly conductive), allowing for eventual ground faults after the insulation flakes off from vibration.
This could explain why the older DR's have a high chance of electrical failures if they have been found in a "stuck" condition. Thoughts?
Sincerely, David
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Post by birkie on Sept 5, 2019 14:16:53 GMT
Yes, I agree that an errant control can cause such a cascade failure. I also wonder if stuck floats might also cause the same sort of breakdown in machines whose controls are/were fine. I have two DRs that show poor isolation between the motor terminals and ground. One just had a stuck float, and the other had a stuck float and was seized. The DRs relied on refrigerant flow to cool down the windings, which obviously stops happening when the float is stuck. Run for a long time (overnight?) in that condition, it's possible it may get hot enough to increase the reaction rate between the SO2 and the cellulose, and/or start to cause thermal decomposition.
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Post by turbokinetic on Sept 5, 2019 14:30:39 GMT
Yes, I agree that an errant control can cause such a cascade failure. I also wonder if stuck floats might also cause the same sort of breakdown in machines whose controls are/were fine. I have two DRs that show poor isolation between the motor terminals and ground. One just had a stuck float, and the other had a stuck float and was seized. The DRs relied on refrigerant flow to cool down the windings, which obviously stops happening when the float is stuck. Run for a long time (overnight?) in that condition, it's possible it may get hot enough to increase the reaction rate between the SO2 and the cellulose, and/or start to cause thermal decomposition. Very good points. As well, the controls are purely an overcurrent device with no thermal shutdown capability as modern ones have. So the control can't sense if the unit is overheating while not drawing excess current.
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Post by scooter76 on Sept 7, 2019 21:08:51 GMT
I think these are all good theories. The interesting anomaly with mine is that there wasn’t (and still isn’t) any ground short or even any measurable “leakage” to ground from either winding - merely a short between start and common.
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Post by turbokinetic on Sept 7, 2019 22:38:01 GMT
I think these are all good theories. The interesting anomaly with mine is that there wasn’t (and still isn’t) any ground short or even any measurable “leakage” to ground from either winding - merely a short between start and common. That is interesting. Have you verified that there isn't a problem with the wiring at the back or bottom of the control?
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Post by csulaguy on Sept 11, 2019 7:21:27 GMT
I'm trying to skim through this thread myself. To the OP (Ryan) - I have a DR-2 with a pig evap myself. I got back from a Monitor Top acquisition/repair trip and found the same puddle of water (someone unplugged my DR-1, so the food in that fridge is all trash now), but my DR-2 was running, but the evap was sweating at around 54 degrees. I feel heartbroken as well, as I really liked my DR-2, but I'm not giving up on it just yet.
Are you going to keep yours to possibly rebuild?
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Post by Travis on Sept 15, 2019 15:13:44 GMT
Do you think the high side dome and the heat also tends to cook the windings? I haven't experienced many problems with the controls. They have tended to work or they fail and make the unit inoperable.
I suspect that if I was 90 and wearing cotton in a hot smelly environment, I would have given up also.
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Post by turbokinetic on Sept 15, 2019 15:16:41 GMT
....I suspect that if I was 90 and wearing cotton in a hot smelly environment, I would have given up also. LOL you have a good point there as well!
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Post by scooter76 on Sept 16, 2019 16:50:37 GMT
I think these are all good theories. The interesting anomaly with mine is that there wasn’t (and still isn’t) any ground short or even any measurable “leakage” to ground from either winding - merely a short between start and common. That is interesting. Have you verified that there isn't a problem with the wiring at the back or bottom of the control?
There does not appear to be any visible problem with the wiring at or near the control, nor at the grommet where it enters the deck. I think the next step would be to pull the unit off the cabinet, remove some screws underneath, and see if I can validate that the start and common wires haven't shorted together somewhere under the deck. I tend to think that's unlikely, as the failure didn't coincide with moving the unit or any other event which should've caused a mechanical rubbing, etc. to cause a short. Never know until I look, though. I agree it's odd that it would short winding to winding with no ground fault.
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Post by Travis on Sept 16, 2019 23:38:21 GMT
Scooter, I hate to tell you this, but the earlier DRs have a solid deck under the neck piece. You won’t find access to much wiring by lowering the evaporator plate.
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