Samsung Domestic nightmare

[andre_fridge]

Hi All
Looks like I live for electronic faults in town here in plett, I got called into a Samsung domestic frost free fridge freezer that switches itself off & on when it feels like it, AAAAggg easy I thought checked the plug, terminal box, all checked ok, perviously the PCB got replaced as they thought it was that but it still carries on doing the same fault, I checked the low voltage transformer voltages (it supplies the PCB) and this thing is kicking out some very wierd readings, after switching on measured 24Vac , then 84Vac, after the compressor kicks in I get 60Vac. and the unit is still running!!!!!!!

I know that I have heard of this problem before, and as usual have samsung confused with this one

Any body got this fault or heard it please reply

[NoNickName]

60 + 24 = 84.

It looks like you have got a floating potential on the neutral.

[andre_fridge]

Hhhhhmmmmmmm, good point will, check on that !
One thing that I didn't mention that I only just remembered was that while I was lying on the cold kitchen floor waiting for my multi meter from the truck, contemplating swimming with the sharks in the sea was watching the compressor "rocking" as if trying to start and then stopping, as if in split seconds, didn't really start or click off on overload.

that shed some more light on the matter at hand

[Dan]

It looks like you have got a floating potential on the neutral.

Hey, nonick. Care to expound on this phenomenon? In the states, we have a term called "floating" neutral. As I understand it, it means that the neutral wiring is open somewhere and ground is providing the direct circuit. Why do we use the term "floating"? I could learn here.

[NoNickName]

Aux transformers can be 0-24 or -12-0-+12, with the central zero that should normally be neutral, which potential is normally referred to earth.
Sometimes the neutral of the trafo has a floating potential to earth (let's say 60 V).
The three terminals will then have 48-60-72 V potential to earth or 60-72-84 V.

[andre_fridge]

Right went out and checked all the neautrals for on the fridge and no burning or shorts are evident, the floating neautral theory is correct as I monitored it for a while and the transformer output voltage is 24Vac, that is untill the fridge is started and it bumps upto 60 odd volts, phone the samsung agents in capetown and they don't seem to understand what I am telling me, the other thing that i thought of doing is adding a temporary wire from PCB neutral to the main connectors to check if one of the cables are indeed "broken" whats your take on this??
Dan here is one for you if you are working on a 3 phase with neutral installation and you loose the "bonded" neutral before it is grounded, it then in theory becomes a floating neutral and all the voltages start to go ape some of the single phase circuits voltages climb in accordance with the impedance of the load on them, it is very interesting to watch, but extremely costly for the client hahahahaha

[NoNickName]

Well, I'm no expert here, but sometime connecting the neutral to the PE terminal works. Sometimes not, and the result is a big black crispy trafo.
So, to keep risks at the minimum, I would first inspect with the utility company how the local mains is setup.

[andre_fridge]

The customer is a dutch guy and I could just see his face when it goes up in smoke, they are seriously lacking in the humour department when they are here!!!!
I am waiting for a full circuit diagram to get faxed from samsung so will look at that before connecting wires. a cowboy I am not, I get to deal with the cowboys in town, a quote to repair a B65 scotsman icemaker that got worked on was R16500.00 a new one costs R15750, thats the fun I have!