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Post by joneske on May 14, 2018 15:25:54 GMT
Oh wow - the start contact is definitely staying closed, or trying to re-close.
There are several reasons for this. One would be that the start relay is out of adjustment, causing the relay armature to NOT fall back down. This is what you hope for!
I would take a PLASTIC, NON-CONDUCTIVE item, such as a ballpoint pen - and manually press the start contact arm down, separating the contacts. Do this as soon as possible just after the motor starts running. If the arm stays down after you do this, see if the motor will continue running without tripping. If the arm immediately rises back up, that would indicate the motor current is very high and it is actuating the relay again. If the arm stays down and everything seems healthy, then you probably just have relay problems!
I would also again suggest checking the motor current draw, as well as the motor's winding resistance and insulation resistance to ground.
We tried this and it worked in that the arm stayed down. it ran and appeared to begin to cool, then eventually tripped off.
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Post by turbokinetic on May 14, 2018 20:45:37 GMT
Oh wow - the start contact is definitely staying closed, or trying to re-close.
There are several reasons for this. One would be that the start relay is out of adjustment, causing the relay armature to NOT fall back down. This is what you hope for!
I would take a PLASTIC, NON-CONDUCTIVE item, such as a ballpoint pen - and manually press the start contact arm down, separating the contacts. Do this as soon as possible just after the motor starts running. If the arm stays down after you do this, see if the motor will continue running without tripping. If the arm immediately rises back up, that would indicate the motor current is very high and it is actuating the relay again. If the arm stays down and everything seems healthy, then you probably just have relay problems!
I would also again suggest checking the motor current draw, as well as the motor's winding resistance and insulation resistance to ground.
We tried this and it worked in that the arm stayed down. it ran and appeared to begin to cool, then eventually tripped off.
Well, this is a good troubleshooting step, which does eliminate the start relay as being the cause of the tripping. So it went several minutes before tripping?
Do you have a Kill-A-Watt meter? It would be very useful as a next troubleshooting step! www.harborfreight.com/kill-a-watt-electric-monitor-93519.html
If you have one, see how many amps the motor is taking, and what the amps are immediately after startup and if it ramps up to a trip point, or starts very high and stays high until the trip. If you don't have a Kill-A-Watt meter, a regular multimeter with current mode can be used, but it is not as convenient.
Also, it would be good to measure winding resistance and compare it to the original readings from your earlier post. I copied and pasted it here: Start to common: 4.1 Start to run 7 Common to run 3.5
Hopefully the measurements are the same as before.
Also, measure resistance from the power cord terminals to the compressor shell, to see if there's any ground continuity. Hopefully there is not a connection with ground.
If the resistance measurements are not wildly different, and there's no ground fault - then the next step, in my opinion, would have to be current measurement.
Best of luck with it!
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Post by joneske on May 14, 2018 20:49:34 GMT
We tried this and it worked in that the arm stayed down. it ran and appeared to begin to cool, then eventually tripped off.
Well, this is a good troubleshooting step, which does eliminate the start relay as being the cause of the tripping. So it went several minutes before tripping?
Do you have a Kill-A-Watt meter? It would be very useful as a next troubleshooting step! www.harborfreight.com/kill-a-watt-electric-monitor-93519.html
If you have one, see how many amps the motor is taking, and what the amps are immediately after startup and if it ramps up to a trip point, or starts very high and stays high until the trip. If you don't have a Kill-A-Watt meter, a regular multimeter with current mode can be used, but it is not as convenient.
Also, it would be good to measure winding resistance and compare it to the original readings from your earlier post. I copied and pasted it here: Start to common: 4.1 Start to run 7 Common to run 3.5
Hopefully the measurements are the same as before.
Also, measure resistance from the power cord terminals to the compressor shell, to see if there's any ground continuity. Hopefully there is not a connection with ground.
If the resistance measurements are not wildly different, and there's no ground fault - then the next step, in my opinion, would have to be current measurement.
Best of luck with it!
I have that model Kill-A-Watt. I believe I answered most of those questions in this post: "We took readings yesterday. And the news was not great. Start to common was 4.2, start to run 7.1 and common to run 3.2, which was nearly identical to my first readings, but this time the start read 8 ohms to ground. It’s draws 610 watts when first started, and drops to 580 before tripping off. The wiring was somewhat compromised back when I removed the control to replace the back. I had attempted a repair using heat shrink, but it is possible the damage is a little deeper. I am going to try and dig out the grommet and see if that is a potential source, and hope it is not something more serious."
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Post by turbokinetic on May 14, 2018 21:01:25 GMT
Well, this is a good troubleshooting step, which does eliminate the start relay as being the cause of the tripping. So it went several minutes before tripping?
Do you have a Kill-A-Watt meter? It would be very useful as a next troubleshooting step! www.harborfreight.com/kill-a-watt-electric-monitor-93519.html
If you have one, see how many amps the motor is taking, and what the amps are immediately after startup and if it ramps up to a trip point, or starts very high and stays high until the trip. If you don't have a Kill-A-Watt meter, a regular multimeter with current mode can be used, but it is not as convenient.
Also, it would be good to measure winding resistance and compare it to the original readings from your earlier post. I copied and pasted it here: Start to common: 4.1 Start to run 7 Common to run 3.5
Hopefully the measurements are the same as before.
Also, measure resistance from the power cord terminals to the compressor shell, to see if there's any ground continuity. Hopefully there is not a connection with ground.
If the resistance measurements are not wildly different, and there's no ground fault - then the next step, in my opinion, would have to be current measurement.
Best of luck with it!
I have that model Kill-A-Watt. I believe I answered most of those questions in the previous post.
Yes you did answer it. For some reason the only post I had notification on was your one above about pressing the start relay arm down. The post with the readings was a page back. Sorry about that. Replies below.
We took readings yesterday. And the news was not great. Start to common was 4.2, start to run 7.1 and common to run 3.2, which was nearly identical to my first readings, but this time the start read 8 ohms to ground. It’s draws 610 watts when first started, and drops to 580 before tripping off. The wiring was somewhat compromised back when I removed the control to replace the back. I had attempted a repair using heat shrink, but it is possible the damage is a little deeper. I am going to try and dig out the grommet and see if that is a potential source, and hope it is not something more serious.
If the Start was reading 8 ohms to ground, that seems similar to the start-run measurement. This could mean that somewhere in the Run circuit there is some damaged wiring. Hopefully the grommet repair helps to resolve this.
Do you have a 3-wire grounded cord on this unit?
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Post by joneske on May 14, 2018 21:04:24 GMT
I have that model Kill-A-Watt. I believe I answered most of those questions in the previous post.
Yes you did answer it. For some reason the only post I had notification on was your one above about pressing the start relay arm down. The post with the readings was a page back. Sorry about that. Replies below.
We took readings yesterday. And the news was not great. Start to common was 4.2, start to run 7.1 and common to run 3.2, which was nearly identical to my first readings, but this time the start read 8 ohms to ground. It’s draws 610 watts when first started, and drops to 580 before tripping off. The wiring was somewhat compromised back when I removed the control to replace the back. I had attempted a repair using heat shrink, but it is possible the damage is a little deeper. I am going to try and dig out the grommet and see if that is a potential source, and hope it is not something more serious.
If the Start was reading 8 ohms to ground, that seems similar to the start-run measurement. This could mean that somewhere in the Run circuit there is some damaged wiring. Hopefully the grommet repair helps to resolve this.
Do you have a 3-wire grounded cord on this unit?
No, it is the original two-prong style.
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Post by turbokinetic on May 14, 2018 21:09:31 GMT
Yes you did answer it. For some reason the only post I had notification on was your one above about pressing the start relay arm down. The post with the readings was a page back. Sorry about that. Replies below.
If the Start was reading 8 ohms to ground, that seems similar to the start-run measurement. This could mean that somewhere in the Run circuit there is some damaged wiring. Hopefully the grommet repair helps to resolve this.
Do you have a 3-wire grounded cord on this unit?
No, it is the original two-prong style.
Oh man. Was hoping it had been a grounded cord. This would have allowed a power path back to ground through the cord's grounding conductor. That would have made a short to ground anywhere in the system have a big effect on the operation of the motor.
Without the grounded cord, there would have to be an internal short in the system, somewhere, allowing an unintentional current path.
Again I hope you locate a short in in the wiring, however without a grounded cord to carry this short current back to ground, it doesn't seem like this would be causing the symptom you are having.
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Post by 100yearfridge on May 14, 2018 23:34:39 GMT
Hey guys. So I was over there briefly last night, and I measured all three motor leads had continuity to ground, similar to the resistance across the windings themselves. That is except the run winding; it was much lower, around 2.1 ohms. Made me wonder if that is the one partially grounding, leading to high current, causing the start armature not to drop out, then lead to the overcurrent heater tripping.
I'm just hoping the problem is near the control end of the wiring, like near the hole where most of the stress occurs when messing with the control wiring. It has that dovetailed box preventing good access to the wiring, and looks like it is only removable by disconnecting the evaporator. I was thinking Jonseke and I could split it on either side with a Dremel, after pulling the bolts out, then plate it back together with metal straps. I don't see any other good way to get at the wiring leading to the compressor; at least to confirm the nature of the problem.
Has anybody removed the wood, without breaking refrigerant lines?
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Post by turbokinetic on May 14, 2018 23:56:53 GMT
Hey guys. So I was over there briefly last night, and I measured all three motor leads had continuity to ground, similar to the resistance across the windings themselves. That is except the run winding; it was much lower, around 2.1 ohms. Made me wonder if that is the one partially grounding, leading to high current, causing the start armature not to drop out, then lead to the overcurrent heater tripping. I'm just hoping the problem is near the control end of the wiring, like near the hole where most of the stress occurs when messing with the control wiring. It has that dovetailed box preventing good access to the wiring, and looks like it is only removable by disconnecting the evaporator. I was thinking Jonseke and I could split it on either side with a Dremel, after pulling the bolts out, then plate it back together with metal straps. I don't see any other good way to get at the wiring leading to the compressor; at least to confirm the nature of the problem. Has anybody removed the wood, without breaking refrigerant lines? I haven't had experience with a DR to be able to help with the lines and wood removal.
One thing to check while working on it is the winding resistance to ground WHILE you're working on the machine. In other words, as you move the unit around, see if the ground continuity changes with position of the unit (tipping) or with moving the wiring.
I remember reading about a similar issue. That one had internal shorting which was position dependent. This ended up being conductive debris collected inside the compressor housing and making contact at the terminals inside the compressor base.
Either way, I really hope the motor can be saved, even if it requires a rewind.
Sincerely, David
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Post by Travis on May 14, 2018 23:59:59 GMT
Mike,
On the older DR3's the upper deck is a solid plate with about a 1" hole under the dome that allows the three motor leads and the pair of heater leads to pass through. I am not sure when the upper deck stopped being made this way and changed to the design that allows you to access the bottom of the motor leads. You might be able to peak into the heater access hole and see if the deck is solid.
My guess is that if this partial grounding is in the external motor leads, that it's near the control.
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Post by Travis on May 15, 2018 0:02:15 GMT
Yes, I realize I am commenting about an old DR3 unit in a DRA2 thread. I believe they were built the same. I also have a failed DRA2 that was running fine until it failed in this same manner.
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Post by birkie on May 15, 2018 1:32:34 GMT
]Again I hope you locate a short in in the wiring, however without a grounded cord to carry this short current back to ground, it doesn't seem like this would be causing the symptom you are having. I would tend to agree with this - I would say that an external short would be really lucky at this point. It is unfortunate how common internal winding shorts are, relatively speaking. The heat (with the meager draft cooling in the DR), vibrations, and SO2 are quite harsh on the cotton insulation. But is is nice that the older ones like the DRA2 can be opened. Removing the badge and looking through the heater hole is an excellent idea - it'll be obvious right away whether it has the plate or not (I'm betting it does)
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Post by turbokinetic on May 15, 2018 1:44:42 GMT
.....But is is nice that the older ones like the DRA2 can be opened....... it'll be obvious right away whether it has the plate or not (I'm betting it does) Yes. That was my thought after reading up on the DRA2 on here, would be a rebuild. That may be its only salvation at this point.
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Post by Travis on May 15, 2018 2:22:37 GMT
I will tell you that I got between the decks on on of my DR3's once. I removed the unit from the cabinet. I then removed all the screws that hold the decks together, except those in the corner by the float. Then I used my lift to raise the upper section until I could get my hand in there. I chipped out the cork insulation and used heat shrink as far as I could go.
This was the DR3 that was later rebuilt. I did all that and it shit the bed within a couple months. They're 90 years old or 91 if you're lucky. They're not the best design, but they are the coolest looking. I defy you to get a new fridge of any make and keep it running for 90 years. It would probably turn into a puddle of goo.
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Post by elec573 on May 15, 2018 3:06:23 GMT
That’s interesting Travis didn’t know they were built that way . Only 8 ohms to ground is all most a short . Hopefully it’s the wiring around the grommet . Sense you reworked the control maybe moving the wiring around weakened it . The cloth wiring on the drs auctually held up better than the plastic coated wire on the later models . We’ll be interesting to see what you find .
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Post by joneske on May 15, 2018 18:27:11 GMT
I was able to get the grommet out and inspect the wiring as it comes through the opening. It was in relatively good shape, with no sign of bare wire. Obviously not what I was hoping for.
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