Hi All,

I bought a Waeco CF110 (A) fridge second hand and have found an interesting fault I can't diagnoise. Note: The Fridge can run off both 12V and 240V.

In 12V operation the fridge runs perfectly.
In 240V mode once warmed up a (after a period of ~40mins), the compressor will stop for a period of 1 min, then restart.

During the fault period I have seen/felt the following symptoms:

1. Compressor Stops (first indication of issue)
2. 7 Segment LED display turns off.
3. 12V Fan remains running for the duration (until seconds before the compressor restarts)
4. When the 7 segment display turns on again I sometimes get a single LED flash (error LED) indicating low voltage. But I think this may be a side effect of (C) resetting?

My only thought so far is that its related to the primary side of the SMPS (see block diagram (C)), as the fridge runs without issue on 12V

I pulled out the 101N0500 controller board from the black housing (it had a conformal coating) to visually inspect if any capacitors were buldging (didn't take photos, appologies) but all seemed to be intact.

Aside from checking for voltage drop at 12 the terminal (B), what other ideas could I try?



External Waeco Product Label (A)



Danfoss Controller (101N0500) (B)


Danfoss Controller (101N0500) (C) - Internal Block diagram from Wingless's post on another forum. Note: They couldn't fix an issue (different symptom) and replaced with a 101N0510, later model replacement part.



Danfoss BD50 Compressor and all components in the fridge before removal. (D)



External Filter Board (seperate to B) that has a 5V regulator for LCD and micro module. (E) As this is powered from 12V irrespective of input source, I assuming that the 5V regulator on this board is ok.
Link for source.

 

The display is fed by the 5V reg, this is fed from a 12V supply internal to the control box on the compressor. The give away is the display going out on 240V AC. The 240V supply is faulty, best of luck trying to fix that side of the board. On mine the SMPS failed & i now just use it on 12V.

 

Thanks DeBe.

Yesterday I shorted C & T on the 101N0500 controller and ran the compressor for several hours without issue. (2000rpm)

Next thought is to place a 1500Ohm resistor between C & T to run the compressor at 3500rpm to see if this can force the issue without any of the prepherials connected. This will hopefully prove your theory.

When I have the whole unit back together I am going to video the failure, just to get the failure order right.

 

Hi DeBe, Confirmed two items:

1) Definately a power supply issue when using 240V. After a period of time (~50min) I get 1 flash every few seconds.
2) I can only cause the issue when using a 1500Ohm resistor to force the compressor to run at high speed.

So good news is its isolated to the 101n0500 module, not sure how simple this will be to diagnose.

 

If you cant fix it then the cheapest way is just use it as a 12V fridge, & if you want to use 240V then buy a 240V ac to 12V dc powersupply.