Hotpoint FFA47X Fridge Freezer

[budm]

Re: Hotpoint FFA47X Fridge Freezer

"Presumably meter on 600VAC. Touch ground first when I know where it is then probe chips." Set meter to DCV, 20V scale or auto range, check between GND pin and VCC pin as suggested.

[Rhothgar]

Re: Hotpoint FFA47X Fridge Freezer

notches, circle in the corner etc are the same, just different makers using different markings.

meter both pins on the chip, and set the meter to 10vdc
i'm expecting (hoping) for either 3.3v or 5v

you WONT get a shock from the chip even if you stuck your finger on it.

What about the triacs? Should I check them too? I know they are big voltage and AC I think?

[stj]

Re: Hotpoint FFA47X Fridge Freezer

triacs - stay away from.

the input and output are 230vac, but the control pin is 5v and if you short it - you blow the controller.

[Rhothgar]

Re: Hotpoint FFA47X Fridge Freezer

I've got plenty spares for the triacs stj!!!

The EEPROM is showing 0.231 volts in 20VDC scale and same on 2VDC scale so it looks like it is not switching the chip on.

Do I need to take any readings from any other pins on the EEPROM or just the Vcc and GND?

[budm]

Re: Hotpoint FFA47X Fridge Freezer

0.231VDC between VCC and the GND pin is not going to be enough to run the IC, you will need to trace out the VCC pin to see where it goes to, the VCC should be supplied by some kind of Voltage regulator somewhere on the board. You should also check the resistance between VCC pin and the GND pin to see if it shows low resistance or not.

[Rhothgar]

Re: Hotpoint FFA47X Fridge Freezer

0.231VDC between VCC and the GND pin is not going to be enough to run the IC, you will need to trace out the VCC pin to see where it goes to, the VCC should be supplied by some kind of Voltage regulator somewhere on the board. You should also check the resistance between VCC pin and the GND pin to see if it shows low resistance or not.

Right! When on continuity, it beeps momentarily and then stops. Remove proves, wait 10 seconds, do it again, short beep then stops.

Turned scale up to max and then down onto 2K scale. It reads 1.958 so 1958 Ohms. Obviously this must mean a component is blown somewhere.

Perhaps the chip itself?

I saw a video on the net somewhere about the LeakSeeker 88 which said that, IIRC, the closer you get to the fault the higher the resistance becomes? Is is correct?

I will try to trace back and do further readings some point this evening.

[stj]

Re: Hotpoint FFA47X Fridge Freezer

right, i was kind of expecting that.

now i need to go back to the foto's and see which pins the mains goes into the board through.
because i think the board is not getting power.

[Rhothgar]

Re: Hotpoint FFA47X Fridge Freezer

right, i was kind of expecting that.

now i need to go back to the foto's and see which pins the mains goes into the board through.
because i think the board is not getting power.

I think it is because it is warm after it's been left on.

Tell me how to safely probe the live and I will check them on the fridge with board out.

The earliest photos show N and L marked but you know me by now I am wary of just probing.

Another thing is and I will upload a photo in a minute, I am getting high resistance to certain pins in locale and then 10 on other side of some 103 resistors.

To me, it is looking like the resistance is in the chip and therefore I assume rightly or wrongly that the chip is damaged internally.

As always, I bow to tie greater knowledge and superiority.

[Rhothgar]

Re: Hotpoint FFA47X Fridge Freezer

On the right of the photo is the 8 leads of the EEPROM.

The bottom left of the 8 pins is Vcc and bottom right is GND.

If I measure from Vcc to pin above I get 11000+ Ohms. No idea if this is right but logic says not.

When I measure to pass North of the 3 no. 103 resistors in top left of photo I get 10,000 Ohms i.e. the value of the resistor. When I measure to the pad nearest to the south of the middle 103 I get 1915 Ohms. That pad goes through the south of the 103 to its right (103 immediately to left of Vcc) and onto GND.

you can probably see it.

I hope the above makes sense.

[stj]

Re: Hotpoint FFA47X Fridge Freezer

your supposed to be doing voltage not resistance.

set your meter to ac higher than 300 and check between the 4 blue wires in a row - any one will do, and the brown wire next to them.
that should be 230-240vac mains.

[budm]

Re: Hotpoint FFA47X Fridge Freezer

Around 2K Ohms between VCC pin and GND pin should not be enough to cause the VCC line to be at <1V. You need to find if you do have power on the main section first and then try to locate the Voltage regulator IC.

[Rhothgar]

Re: Hotpoint FFA47X Fridge Freezer

Oh! Sorry. Sounds hopeful that 2000 Ohms is not unexpected.

This is where it would be useful if I had a variable voltage power supply!

I cannot see any wires because the female spades are in a plastic connector block behind he fridge top panel.

On the first photos I uploaded, the N and L were marked by a testing company so I would assume they are correct.

Being high voltage, one should never assume so to play safe I have a few questions.

1) if I am wearing rubber wellies, can you confirm that I cannot get a shock assuming no other part of me or clothing touches anything else that is earthed?

2) can I use a fridge hinge as earth or GND? Is it likely to be earthed?

3) is it safe to use any confirmed earth anywhere on the appliance or am I likely to do more damage somehow?

4) what would happen if I touch two lives with the probes?

I apologise if these are basic questions. Just want to be safe than sorry.

[stj]

Re: Hotpoint FFA47X Fridge Freezer

mains earth and N should not be confused.
as for the boots - unless you step on the circuit i cant see much use for them.

that fridge must have fuses, and you shorted the power when you jumped the heater-wire.

[Rhothgar]

Re: Hotpoint FFA47X Fridge Freezer

mains earth and N should not be confused.
as for the boots - unless you step on the circuit i cant see much use for them.

that fridge must have fuses, and you shorted the power when you jumped the heater-wire.

I thought it prevented a live going to earth through me!

So if I probe a live wire with bare feet and no probe to neutral I would not get a shock? Surely I would.

I cannot see a way of removing any panels. There are screws but I don't think it's meant to be serviced.

It looks as though the case is built, wired, internals out in and then expanding foam to fill the voids between fridge compartment and metal casing.

[keeney123]

Re: Hotpoint FFA47X Fridge Freezer

Perhaps Stj can inform you how to check out the grounding system in your house's electrical so you will know you are safe. I live in the US so I am unaware of how the United Kingdom's system is.

[stj]

Re: Hotpoint FFA47X Fridge Freezer

u.k. wiring depends on the age of the building.
modern buildings the earth and N are bonded at the breaker panel.

older buildings, they arent and the earth is bonded to the incoming water pipes.
why?

[Rhothgar]

Re: Hotpoint FFA47X Fridge Freezer

u.k. wiring depends on the age of the building.
modern buildings the earth and N are bonded at the breaker panel.

older buildings, they arent and the earth is bonded to the incoming water pipes.
why?

i need to know how to find an earth (GND) or Neutral on the appliance ( not the house) because surely if I probe the wrong terminals because J cannot see the wires on the fridge then I will blow something else up and perhaps not the triacs this time hence asking the questions in previous thread.

Crikey. The wiring in the house is still on a Bakerlite panel. I had a wire between the garage and the house melt a couple of months ago.

EDIT: Just reading an article on a website called the circuit detective and it's given me an idea.

As my house wiring is very old and there are no breakers, would it be an idea to plug the fridge into an extension I have which has a 30mA breaker. If it trips then I know that there is a short circuit in the appliance.

[Rhothgar]

Re: Hotpoint FFA47X Fridge Freezer

I tested the first 11 spades on the fridge.

They relate to the photo uploaded.

I assumed GND or Neutral was the far right trace at the top of the photo.

The 7th trace in from the left is the only one that measured 240VAC.

[keeney123]

Re: Hotpoint FFA47X Fridge Freezer

i need to know how to find an earth (GND) or Neutral on the appliance ( not the house) because surely if I probe the wrong terminals because J cannot see the wires on the fridge then I will blow something else up and perhaps not the triacs this time hence asking the questions in previous thread.

Crikey. The wiring in the house is still on a Bakerlite panel. I had a wire between the garage and the house melt a couple of months ago.

EDIT: Just reading an article on a website called the circuit detective and it's given me an idea.

As my house wiring is very old and there are no breakers, would it be an idea to plug the fridge into an extension I have which has a 30mA breaker. If it trips then I know that there is a short circuit in the appliance.

If you are worried about being zapped by the metal on the refrigerator then you need to know your house wiring. If you have the neutral wired to the ground in your panel you will have three wires including ground to a single phase outlet. When you measure voltage on your outlet you will have three possible combinations (1)Ground to Neutral, (2)Ground to Line voltage and (3)Neutral to Line voltage. Number (1) should have no voltage, (2) you should measure line voltage, (3) you should have line Voltage. The two with no voltage are Neutral and Ground. Now to verify this switch meter two lowest AC voltage should still be no more than 1 volt AC. Now you can switch to ohms and verify a short between neutral and ground. With refrigerator unplug ohm measure ground of plug to bare metal on refrigerator. I am not sure of the wire code in UK either you will have one or two points on the three point plug of the refrigerator that will ohm out to the metal. One point connected to metal of the refrigerator you have a separate ground and neutral. Two points connected then code says it has Neutral connected to Ground on equipment. Three points connected to bare metal means you have a short of the line to ground, your breaker you pop.
Your garage wire burning up would mean the wire was to small for the breaker rating. If no breaker then you have a fuse box?

Do you have a ground connection going to plug? That would mean you only have two prongs in outlet. Anyway these are some things you can do but I would refer you to STJ as he is in the same locality.

[Rhothgar]

Re: Hotpoint FFA47X Fridge Freezer

I was just worried about probing a live circuit and blowing something on the PCB again.

I am trying to work out unsuccessfully but trying to learn as I go along which traces should have a live because I cannot see wiring in head panel.

The big black rectangular component on the PCB marked J1 - the top left lead ( from last photo) on the u/s of PCB connects to trace 1 but when I meter trace 1 it's not getting 240VAC and I don't understand why.

I've looked at legs on ACS108 data sheet and do not understand if COM is live or neutral.
I'm trying to think logically about which side of PCB is live and which side is neutral.

The company that marked board with L and N in marker pen seemed to indicTe that all 4 traces (7-11) were live but I'm not getting 240VAC in traces 8-11?