Norcold power supply - FIXED!!!

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MisterBK

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I have a Norcold DE728 AC/DC refer in my 1984 Carver. A while ago it started an intermittent loud buzz while on AC; you could hear it from inside as soon as getting to the cabin hatch. No cooling during the "buzz periods" which lasted a while (while on 110v).

Now, it doesn't function at all on AC; 12v is fine. My assumption is the power supply & that the buzz might have been a failing relay. If that sounds right, I would like to just replace the power supply. I have not pulled the old one yet to see if there is a burned circuit board or an obvious blown component.

Anyone know of a source for this discontinued part? I've checked Norcold & several RV/marine sites to no avail.
 
when docked or on the gen you have your battery charger on so why not run on 12V
 
most dual voltage units are 12 volt units with a small inverter to take the 110v down to 12 volts. sounds like your inverter has failed. should be easy to check when you pull the unit out.
 
Some people call them NeverCold. I agree with the other poster that the inverter has probably failed. Can you just disconnect the 110V from it and run it on 12V?
 
Brian - Make sure you let us know how you make out. I have the same fridge and had a similar problem for short time last year. It went away but I was thinking about replacing the fridge figuring that it would come back at some point. The fridge is 24 years old and I didn't think that it would be worth fixing.
 
Thanks for the input, folks. I am running it for the time being the way pdecat suggested, but I'd rather for the long term use the 110 while in my berth (most of the time ... I stay on board a bunch & as a home office).

Since the 12v is workng fine, I haven't pulled the PS unit out yet ... working on more fun stuff like adding new electronics & upgrading my inverter. I plan to tackle it w/in the next few weeks, though. I'll post what I find.

Jim, the problem on mine went away for a while, too so I was hoping it was just a fluke, but, alas, it came back & the 110v quit. I'm not even thinking of refer replacement because it works great except for the 110 power.
 
A friend had one of those old fridges, needed a relay. I suggested Radio Shack and they actually had onw that actually worked. But I can't remember if the fridge was Norcold or Dometic. Pretty sure it was one or the other...
 
Well if it is buzzing more on 110VAC and doesn't work but works on 12VDC its probably not an inverter guys. I would think it is more of a power supply and buzzing usually means a filter capacitor or the diode bridge (full wave rectifier) has gone bad in the AC power supply. In fact my DE0061T which is only 2 years old when plugged into 110VAC lights my 12 volt breaker switch LED when it is switched on to 110VAC. We never use it in the 110 mode and it makes ice cubes in the freezer within 2.5 hours of turning it on. I had no problem with the original unit that lasted since 1993 other than the bottom was rusting and the new units draw less current at 12volts DC than the old units. They have a new style compressor in the units made in the last 3 years. Here is a place that sells replacement power supply boards for Norcolds.
http://www.rvstuffusa.com/interfacepowersupplyboardsfornorcoldrefrigeratorsbydinosaurelectronic.html
Bill
 
Bill, I might be wrong but that technology looks a litle new for 1984 frig.
Jim
 
You could try this, go to radio shack and purchase a 5 amp 12volt DC power supply. The kind you plug into AC and it gives you 12VDC out. I bet it would work if you attached it where the positive and negative wires went into the frig. If it works than you have your answer. Its cheap down and dirty but if the frig works on 12volts DC it will now work on 110VAC when you are hooked up at the dock. If it doesn't work take the supply back to Radio Shack I believe they have a no questions asked policy.
Bill
 
Years ago I fixed an AC-DC fridge in a Winnebago that needed a power supply. I found a match at one of the local Electronics stores. Similar to Radio Shack. I think most of that stuff made in America is made up of redily availble assembly line parts.

As opposed to the Chinese who order a 'run' of what the Engineers think they might need. After that 'Run' is over, there will never be another part exactly like it. Your faced with replacing the unit if its Chinese.
 
OK ... here's the update. First, thanks to all who offered all the advice.

I pulled the power supply, opened it up. Has one PCB and a 3-pole relay. The 12v DC is 'inverted' to 23v AC. The AC side drops the voltage on the secondary output of the transformer to 23V (voltages tested OK).

ATT00013.jpg


The one pole in the relay was fried, undoubtedly the one that was doing all the chattering before it "welded" to one side.

DSC00911.jpg


The original relay is no longer available (what a surprise), but I found Dayton makes a replacement (5X841 - 3PDT).

DSC00958.jpg


Replaced the relay, reassembled, and had ice in an hour on AC. [:-jump2]
icon_speech_yeah.gif


I got an extra relay if anyone here needs one. $5 including shipping for BE folks. Lemme know.
 
CONGRATS!!! You are the only person I have ever heard of who was able to do a repair to a Norcold. The mnftr is of no help. Good job!
 
I know this an old posting, but I had this problem with the relay going out on my DE728 this week and used MisterBK's instructions. I know nothing about fixing things but this worked great. Took about 45 minutes and saved me $1.5K. All the stealerships told me that nothing could be done to fix this dinosaur. Ebay was loaded with 5X841's and Grainger has them. Also, don't worry about the molded numbers pattern being different on the bottom of the 5X841 from the original Matsu****a 70428. I just installed it as is and it worked. Thanks MisterBK.
 
That's what I love about this site. It is amazing how much the members support each other! Congrats on the repair.
Rob
 
Just to archive useful info on the de728 I'm pasting this in for the next guy. Not sure of the original source but here it is:

Chatter Protectors Todd 10-8-08
The Type "B" chatter protector, the orange rubber one is basically used to operate a 110V DC relay off of 110VAC. It basically consists of a crude rectifier and something that appears to be protection from voltage spikes.
On later models, the chatter protector was removed & AC relays were used. I have converted many DE728, DE828 & DE704 units to an AC relay & eliminated the chatter protector completely. I have never had an issue. I do have a good tested "B" in stock. I do not know what exactly the "A-1" chatter protector does, as units using it already have an AC relay. The "A-1" is an external metal box that plugs inline with your AC cord. The "A-1" design is older than the "B" design. I would assume that it is for noise supression or voltage spike protection, as removing it completely does not seem to effect fridge operation. In both systems, the chatter protector is only connected via the relay directly to the transformer & does not connect directly to the inverter/oscillator at all. The switching relay keeps them isolated. We have a Norcold boneyard.

Also, I found that the old GMC motor homes had the DE728 so parts may be scavanged. HAPPY HUNTING.
 
You have to bear in mind that the "stealerships" and many repairmen have an agenda: to separate you from as much money as possible. Something that might need a $10 relay "can't be repaired" or "parts aren't available" so they'll try to sell you a new unit at a far higher cost.

Of course the price of labor enters into this; sometimes the labor involved in diagnosing and fixing the problem is more than a new unit would be. I can't count the times I've spent hours trying to fix some gadget, if I were paying a repairman I'd simply buy new.
 
quote:
Originally posted by ddurand

Some people call them NeverCold. I agree with the other poster that the inverter has probably failed. Can you just disconnect the 110V from it and run it on 12V?

Click to expand...

People that call them NEVERCOLD are just ignorant. The newer units do a great job of cooling and keeping food both frozen and cold. They do so using very little AH's on 12VDC. When I say the newer line I am talking about 2006 and newer.
I should rename my DE0061T to NEVERWARM or better yet ALWAYSCOLD.
Bill
 
BillyIII: I've got a 1989 sabre with the original norcold. We've owned it for the last 2.5 years and it works great, although it's appetite for amperage seems kind of high.
 
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