GE Monitor Top Switch/Thermostat Issue?

pipercollins71

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Model Number
CK-26-A16
Model Number: CK-26-A16

Brand: GE

Age: More than 10 years


I've got a 1936 GE Monitor Top. It's a beauty and it's been running in my retro kitchen for over 3 years. All I've done is clean it up, paint it, and replace the door seal. It still runs great. Except...more and more often it's deciding not to run. That is, not to switch on.

From time to time I'll notice it's not cold when I open the door. It was running, but then for some reason it stopped cycling. All I have to do to jump start it is to turn the switch to "off" and back to "on" again, and it starts right up. It gets cold again just fine and displays no sign of trouble. Maybe for a day, maybe several days. But it's getting to be more of a daily occurrence.

I've been through the housing for the contacts, and I've cleaned the contacts and everything else there. Those are fine, or I'd think it wouldn't run at all. It seems to me whatever is sticking is in the switch, or maybe the thermostat. I'm a little bit lost there, though. I can see what's going on with the contacts and the basic wiring. Can anyone help me troubleshoot from there?

Thanks much.
Bill
 

rickgburton

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It sounds like a thermostat issue. When the thermostat closes, the contacts are not making a good connection. You should be able to find a universal fit thermostat from Ranco or Robert Shaw.
 

pipercollins71

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Okay, sounds good as far as it goes. But what's involved replacing a t-stat on an old Monitor Top? The contacts were easy to get to. But I'm not sure what I'll have to do to get into the t-stat.
 

pipercollins71

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Here's what we're working with...
The contacts are in a housing mounted between fins inside the back of the round "monitor" top. The switch and thermostat setting are at the front. But that's a bigger rats nest of wires, and I didn't want to take that apart blindly. There must be a probe of some kind, too, right?

100_2770.jpg.html

100_2770.jpg photo by pipercollins35 | Photobucket

100_2777.jpg.html

100_2777.jpg photo by pipercollins35 | Photobucket
 

rickgburton

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This is the part I need to see and you need to be extremely careful with the wires or the insulation will crack and fall off. The thermostat and switch contacts can be cleaned as long as the gas hasn't escaped from the thermocouple on the thermostat. You need to know what you're doing. This is not a simple repair and on a scale of one to ten, I give it a ten.
Monitor Top.jpg
 

pipercollins71

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LOL. That's why I'm here.

I do have some antique appliance skills. I had a sideline for a while restoring several 1940s-50s Chambers gas ranges. I know what you mean about the wiring. That's exactly why I wanted some advice before I try to take things apart. I'm not a pro with these old fridges, but I do know what I don't know. If that makes sense.

The thermocouple must still be intact at this point, because as long as it decides to start up, it does run and will cycle, at least for a while. Maybe days. It will be a few days before I can take the time to get into it with proper care and attention. I'll let you know and maybe get some pictures of the wiring at the switches.

Thanks for the direction.
 

rickgburton

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I've worked on a few of these but you need to remember, they were an antique when I was born. I can tell you what's repairable and what's not and what parts you can use as a replacement for an original part but as far as actually taking it apart, that's going to be your job to figure the easiest or best way to do it without damaging any of the wires. You want a big work space and the monitor top does come off the machine to make it easier.
 

pipercollins71

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OK, here we go...
Sorry for the delay. This thing was running pretty well for the most part and I had a lot of irons in the fire. Now it won't run for more than a couple hours before quitting and not starting up again without assistance...so it's moved up the priority list.

I believe I can get into the switch housing now and look for ways to clean and adjust things. If there really is a replacement available, I'd like to know my options. But before I proceed, please read on and share with me any advice.

I managed to carefully straighten the probe and detach the switch housing, so I could raise it up above the monitor top. I haven't disconnected anything yet, other than the mounting screws and the knobs. So here are some pictures of what we're looking at.

IMG_1745.JPG IMG_1747.JPG

The markings on the side read as follows:
GENERAL ELECTRIC
057-812 GR. 27
CAT. MIA121
110 A/C 1/8 HP
??50 or 60 HTR 3.4 A
?????42 1688?3?
?????26 1974??

The markings get more faint toward the bottom and front edge, hence the question marks.

The on/off/defrost knob (upper) knob was a (hopefully minor) casualty. Some piece broke off the back as I pried it loose. I expected it to press onto a shaft similar to the other knob, but it's actually quite different. There's a square shank that goes through between the contacts, with a curved part that I guess spreads the contacts open when the switch is in the "off" position. I can probably salvage the knob well-enough, but I'd be interested in an intact replacement if anyone has one available. My blunder does not seem to have damaged the contacts.

IMG_1749.JPG

Thanks, Bill
 

rickgburton

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Bill, how many wires on the thermostat? Also, where does the capillary mount? And how long is it?
 

pipercollins71

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I haven't taken it apart any further before asking your thoughts, so I don't know for sure how many wires connect it. Must be either 2 or 3. The capillary threads through the top of the freezer box and out the side of it, with the bulb mounted vertically on the side of the freezer near the front edge where it meets the door as it closes. I'm not on site at the moment, but the bulb is probably 3 inches long, maybe 4. The whole capillary lead must be about 18 inches.

I can measure that more precisely Wednesday. And if I need to further disassemble the unit to tell more about the t-stat, I can do it then. I was hoping the numbers and photos would give you more to go on...but even the numbers are 80 years old. LOL.

I'll probably open it up and see what can be cleaned and reassembled and see how that goes. Nothing (except that knob) is actually broken...so far.
 

rickgburton

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OK, there's only two wires on it. The original part number is Cat: M1A121; Ranco A30-180 will work as a replacement and so will Mars 26244. I know the Ranco is available but still trying to locate the original.
 

rickgburton

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The Ranco A30-180 control is a kit that comes with different hardware and a universal control knob. It has a 42" thermocouple that can be rolled up and tucked away (the extra).
 

pipercollins71

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Alright, I think I follow you. Either of these replacements could be mounted, requiring more or less ingenuity, where the old control was. I can thread the new capillary through where the old one was, coil away the extra. (Although 42" is a lot...I'd say the original is 24".)

It's a little hard to tell from the pictures, I assume the new controls have a couple terminals for (carefully) connecting the old wires. So where the old control had one knob for off/on/defrost and a separate knob for temp setting, the new controls are all one knob. Right? So like a newer fridge...probably "off", and then a range of temps for "on".

Am I missing anything?
 

pipercollins71

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Okay, here's the big update. I found a Ranco switch from an on line distributor and made the swap out. It did take some creative mounting in order to reuse the original switch knobs (one of which is a dummy, now). But it's all back up and working and looks good now. All for ~ $50. Good for another 76 years. LOL

Thanks for all your help.
Bill
 

pipercollins71

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Well Rick, a month later, the contacts on this old Monitor Top are fried. I don't *think* that has anything to do with previously replacing the switch. It ran fine for a month.

Do you have a replacement part suggestion for the contacts/relay? Or if it's advisable, I could re-bend the existing contacts so the points will line up again. But I'm thinking that's a stop gap solution at best. Any advice is appreciated.
 

rickgburton

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Whenever you work on antique appliances and you run into something like that, your creative side needs to kick in. I've had to re-manufacture more parts than I replaced with new or used. More than once I've had to re-manufacture/repair contact points. I can't tell from the picture if the lower contact is steel or spring steel but replace the lower contact by manufacturing a new one with the same material. Then what I would do for a contact point is braze a point with silver brazing rod. If it's spring steel the braze won't take so you need to drill a small hole through it first then braze both sides. It needs to be cleaned, almost polished, with some fine sand paper and wire brush. If you want it to last, you'll need to clean the points once a year.
 
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