|
|
Post by mrhoot on Apr 22, 2018 0:34:25 GMT
Hey guys,
Picked up a 1939 GE flat top a while back from the junkyard. The body is in good shape and every part is pretty clean (inside the top especially, the condenser not as much). So I have put a new cord on it, a new relay on it (supco ro81), and then swapped it for a hard start (supco 3n1). After scouring these boards, I am fairly certain everything is wired correctly. The light works (big whoop). I can not however get the ol CF to kick on. The SO2 was percolating the other day in the heat. Of course, I can not find my modern digital multimeter. My crappy ancient analog one claims I am getting 1.5k ohms across common to run as well as common to start. I have also tried the ol’ 2x4 to the condenser (dont worry, i only hit structural, no fins).
Is she toast folks?
If so, anyone ever done a minifridge guts retrofit? I have a donor waiting and figure i can flare and connect refrigerant lines like automotive brake lines? Am I crazy?
Sincerely,
A Hoot
|
|
|
|
Post by mrhoot on Apr 22, 2018 0:42:23 GMT
For the record the unit is a PB6-39-A.
|
|
|
|
Post by ckfan on Apr 22, 2018 1:20:50 GMT
Hmm, that really sounds suspect but...
Let’s make sure your multimeter is working right first. If the reading that it is giving is correct that means your compressor windings are completely burnt out. That seems pretty unlikely for me. I’ll let the experts chime in.
|
|
|
|
Post by cablehack on Apr 22, 2018 12:47:38 GMT
Is there 120V present between the common and run terminals? If there is, and the motor doesn't make any sound at all, it would seem to indicate an open run winding. If the 120V is not present, the thermostat or wiring of the relay would be the next things to check.
Another test is to connect 120V directly to the run and common terminals of the motor and power up. There should be a loud hum from the motor, and if you momentarily bridge the start connection to the run connection, for about a second, the motor should then start. The motor must not be left in the not started condition for more than a few seconds, or the run winding may burn out, so it must be started as quickly as possible. The start connection must be removed soon as it does start so as not to burn out the start winding.
If the motor can be made to start and run this way, it points to something else being the fault. Bear in mind that in running the motor this way, there is no overload protection so do not leave it running unattended.
A plug in power meter is a particularly useful tool for diagnosing improper operation as the current draw will reveal much about the operating conditions.
|
|
|
|
Post by mrhoot on Apr 22, 2018 13:11:46 GMT
Hmm, that really sounds suspect but... Let’s make sure your multimeter is working right first. If the reading that it is giving is correct that means your compressor windings are completely burnt out. That seems pretty unlikely for me. I’ll let the experts chime in. Yeah, if anything, i would expect that one winding would be blown and the other fine. I did take these readings on the wires, not the terminals on the condenser. The wires are roached/original though so that may impede good readings. I just learned about tipping it back to get to those so i will try later. Im trying to find a sign of life before going through a full rewire. |
|
|
|
Post by mrhoot on Apr 22, 2018 13:17:21 GMT
Is there 120V present between the common and run terminals? If there is, and the motor doesn't make any sound at all, it would seem to indicate an open run winding. If the 120V is not present, the thermostat or wiring of the relay would be the next things to check. Another test is to connect 120V directly to the run and common terminals of the motor and power up. There should be a loud hum from the motor, and if you momentarily bridge the start connection to the run connection, for about a second, the motor should then start. The motor must not be left in the not started condition for more than a few seconds, or the run winding may burn out, so it must be started as quickly as possible. The start connection must be removed soon as it does start so as not to burn out the start winding. If the motor can be made to start and run this way, it points to something else being the fault. Bear in mind that in running the motor this way, there is no overload protection so do not leave it running unattended. A plug in power meter is a particularly useful tool for diagnosing improper operation as the current draw will reveal much about the operating conditions. Thanks for chimig in! I read about this direct power/bridging test yesterday on another topic. I will try that later today. The original relay is gone. It was present when i got it but severly roached out so i swapped with r-081. Currently it has a 3n1 supco on it (the r-081 didnt appear to work, yet). How many internal parts in the thermostat could be at fault. It has nice spring tension when twisted and seems to click at the right on/off spot. Would it be wires only or is there something else that could be the culprit in there? |
|
|
|
Post by ckfan on Apr 22, 2018 14:07:06 GMT
As cablehack suggested I think the first step is to see if you are getting 120 at the compressor terminals. You could also disconnect the wires from the thermostat and use your ohm meter to see if it has continuity.
|
|
|
|
Post by mrhoot on Apr 22, 2018 19:39:08 GMT
As cablehack suggested I think the first step is to see if you are getting 120 at the compressor terminals. You could also disconnect the wires from the thermostat and use your ohm meter to see if it has continuity. Aaaaaaaaaawwwww snap! I hooked it up to the cord directly, plugged it in, HUMMMMMMMMM, jumped the start wire over to the run wire, and it kicked right on like it was late for something! So Im thinking this points to the thermostat, yes? |
|
|
|
Post by mrhoot on Apr 22, 2018 22:18:55 GMT
Just did the old jump again and let it run for a minute to see if it would cool. Took about 45 seconds to a minute to get the juices flowing through the evap. Started cooling quickly. I unplugged it after that to be safe. But good news!
|
|
|
|
Post by cablehack on Apr 23, 2018 1:45:38 GMT
That's a huge relief! OK, so all is good with the sealed unit then  So, that narrows it down to the thermostat or relay. The thermostat is easy to eliminate, simply by short circuiting its terminals and seeing if the motor runs. |
|
|
|
Post by mrhoot on Apr 23, 2018 2:00:22 GMT
That's a huge relief! OK, so all is good with the sealed unit then So, that narrows it down to the thermostat or relay. The thermostat is easy to eliminate, simply by short circuiting its terminals and seeing if the motor runs. How would I go about ‘short circuiting its terminals’? Also, im pretty sure i wired the relays in right, if y’all can help out on a photo of a similar scotch yoke wired with a modern relay it would eliminate or elicit the relay/wiring I would think. |
|
|
|
Post by cablehack on Apr 23, 2018 13:27:43 GMT
|
|
|
|
Post by mrhoot on Apr 23, 2018 18:34:39 GMT
I connected the two thermostat wires and the motor immediately ran when plugged in. Relay is good! Wiring is correct! Thermostat at fault! Can they be fixed or do I just need to purchase a replacement? Im gonna rewire the whole thing now just in case I cant see a blowout somewhere before I order a new thermostat.
Edit/update: rewired the top to bottom connections with 16 gauge wire. Still no operation without shorting the terminals on the cold control. Just gotta grab the right ramco. I saw VC1 on another thread as usable I think?
|
|
|
|
Post by cablehack on Apr 23, 2018 23:42:08 GMT
It's worth opening up the thermostat for a look, but don't remove the bellows from the rear, because they will stretch and put the control out of calibration (words of personal experience here!).
I just wonder if it's something to do with the defrost function holding the control off. A modern Ranco will get you out of trouble if necessary, but knowing how well the originals were made, I would be curious to know what the fault is.
|
|
|
|
Post by mrhoot on Apr 24, 2018 0:10:47 GMT
It's worth opening up the thermostat for a look, but don't remove the bellows from the rear, because they will stretch and put the control out of calibration (words of personal experience here!). I just wonder if it's something to do with the defrost function holding the control off. A modern Ranco will get you out of trouble if necessary, but knowing how well the originals were made, I would be curious to know what the fault is. I havent been able to find any obvious way to open it. I found how to remove the plastic cover from the wire connections, and saw the bolts for the temp sensor line (which i assume is what leads to the bellows that i dont wanna mess with). It honestly looks like there is a spot that should be screwed shut but is just factory filled with plastic as if it was pressed as part of the body of the control. I would post a photo but I cant figured out how. |
|
