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Old 09-11-2020, 19:15   #16
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Re: Norcold DE-251E repair

This is the basic circuit of the 12V DC inverter, to drive the transformer which powers the compressor. This treansformer is used for both the 12V DC & the Mains. Norcold obviously use Engel units in there fridges.
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Old 20-02-2023, 23:06   #17
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Re: Norcold DE-251E repair

I have the exact same problem with a Norcold DE-390D which uses the same power supply, which apparently is out of production. It's been a while since this thread was updated, so I wonder if you were successful in using a 12V inverter to allow your fridge to run on 12V, with or without a shore power cut-off relay to disconnect the inverter when on shore power? It seems a 300W inverter would provide plenty of juice with a pure sine wave at 60Hz for less than $100 and what you suggested would be easy enough to implement. I just want to confirm that it worked. Hate to add an otherwise good fridge into a landfill.
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Old 21-02-2023, 06:47   #18
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Re: Norcold DE-251E repair

Hey Whidbeyben,


I installed a 150w inverter (non-true sine) that does perfectly ok.
In addition created a relay with two power cords, one leg connects to the 120v feed and the other to the inverter, when 120v comes in it'll route the 120v direct to the fridge - when the power drops it will default to the inverter. No issues with anything, just make sure your inverter doesn't need to be "turned on" every time you apply power, a hard power switch type or no switch type is needed.


Thanks,


--Phil
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Old 21-02-2023, 21:40   #19
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Re: Norcold DE-251E repair

Thanks so much for the update. I've got a 300W inverter standing by for me to pull the fridge out of it's cubby hole. Just have to pick up a relay on Amazon. My battery charger probably wouldn't have any issues with supplying the additional 3A to run the refrigerator that's drawing from the battery, but your idea of using the relay should be more efficient, and will allow the house battery to recharge faster.
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Old 06-04-2023, 19:47   #20
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Re: Norcold DE-251E repair

A follow up for the forum readers. A 150W inverter connected directly to 12V battery does power the refrigerator via the 120V plug, but the fan in the inverter made too much noise. I took the power supply off the refrigerator and pulled out the circuit board. A soldered on 0.5A fuse had blown, so I replaced that. This restored the LED Power indicator in the freezer but didn't seem to run the compressor. I then replaced the two K532 MOS FET's on the circuit board ($20 on eBay), which restored normal function to the power supply and to the refrigerator. I was able to do a component level repair with normal soldering skills and $20 in parts. If anyone else has this problem, it may be well worth the effort to check the circuit board for the fuse and consider replacing the transistors since this power supply isn't available for sale anymore. It ended up being simpler than figuring out how to rig up a relay to switch between direct AC power while plugged into shore power and AC power from the inverter when not plugged into shore power.
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