Hotpoint FFA47X Fridge Freezer

[Behemot]

Re: Hotpoint FFA47X Fridge Freezer

Polarized is for DC as it has + and -. For alternating current it has no reason, the polarity is changing very fast. You may want to refer to wikipedia or some similar source http://en.wikipedia.org/wiki/Electrical_polarity

[Rhothgar]

Re: Hotpoint FFA47X Fridge Freezer

Cool! So although the feed to the board is live (AC) it is being converted somehow into DC and the caps with the white strips are DC caps. Perhaps there is a mix on the board?

I will re-upload single photos or at least try to.

[Rhothgar]

Re: Hotpoint FFA47X Fridge Freezer

Here are some revised photos

[Rhothgar]

Re: Hotpoint FFA47X Fridge Freezer

Well. I've spent the last 40 minutes going through the RS online catalogue and it appears that they do not appear to stock capacitors (certainly not) 100V DC or AC in 2.2 uF.

Desperate to get this fridge fixed so will look to grab some desolder braid and a flux pen from them and try to find an identical rated capacitor on some junked PCB I have sitting around.

At least I can test my desoldering skills!

[Behemot]

Re: Hotpoint FFA47X Fridge Freezer

Cool! So although the feed to the board is live (AC) it is being converted somehow into DC and the caps with the white strips are DC caps.

Yep, by a device called bridge rectifier. Or jsut four independent diodes may be used. http://en.wikipedia.org/wiki/Diode_bridge

Anyway, it does not seem to me there is actually any in here so it must be somewhere else in the fridge and here it only controls the freezer.

What is the capacity of that biggest capacitor by the three blue ones?

There are 9 quality 2.2/100 caps http://uk.rs-online.com/web/c/passiv...1&m=1&aaaExp=Y

[stj]

Re: Hotpoint FFA47X Fridge Freezer

make a list of all the electrolytic caps.
include the voltage, the uf, the diameter, and the make+series.

[budm]

Re: Hotpoint FFA47X Fridge Freezer

The power supply circuits uses capacitive power supply (the blue rectangular cap is used for dropping the Voltage to lower value). The power supply is half-wave rectifying, and C20 looks to be the main filter cap, what is the Voltage rating of that cap. RV1 is the MOV.
Check R30, R100. Also check the capacitance of those large blue rectangular caps.
What is the rating of that relay with white paper on top? the coil Voltage will give you some idea of what the power supply Voltage should be.
There is display circuit board that is attached to this board, right?

[Behemot]

Re: Hotpoint FFA47X Fridge Freezer

Isn't it too small for that? Usually such caps I have seen have been big (1+ uF) and it still took only a couple watts for logic circuitry. Here with that big transformer it looks like 10, 20 watts.

[budm]

Re: Hotpoint FFA47X Fridge Freezer

Isn't it too small for that? Usually such caps I have seen have been big (1+ uF) and it still took only a couple watts for logic circuitry. Here with that big transformer it looks like 10, 20 watts.

Just enough to drive the relay.
There are two power supplies, one the SMPS, and one for the relay.
I did not finish tracing the board yet.

[stj]

Re: Hotpoint FFA47X Fridge Freezer

i wonder why it has a reed-switch?

[Rhothgar]

Re: Hotpoint FFA47X Fridge Freezer

Yep, by a device called bridge rectifier. Or jsut four independent diodes may be used. http://en.wikipedia.org/wiki/Diode_bridge

Thank you. I'm getting into this. There's a huge amount to learn though.

What is the capacity of that biggest capacitor by the three blue ones?

I'll check and report back when I get time over the weekend.

There are 9 quality 2.2/100 caps http://uk.rs-online.com/web/c/passiv...1&m=1&aaaExp=Y

They do have them but the problem was they do not stock them at the local branch. Online only so no weekend fix or attempt at fixing.

I blew my first capacitor up yesterday! Will start another thread on another project I have going when I get a minute.

[Rhothgar]

Re: Hotpoint FFA47X Fridge Freezer

The power supply circuits uses capacitive power supply (the blue rectangular cap is used for dropping the Voltage to lower value).

Which blue rectangular cap - C7?

The power supply is half-wave rectifying, and C20 looks to be the main filter cap, what is the Voltage rating of that cap.

I will check all and report back sometime over the weekend.

RV1 is the MOV.

What is a MOV please?

Check R30, R100. Also check the capacitance of those large blue rectangular caps.

Will do and report back.

What is the rating of that relay with white paper on top? the coil Voltage will give you some idea of what the power supply Voltage should be.

Hopefully, it will state this on it when I remove the paper. Otherwise I'd have no clue how to do that but can hopefully research that online.

There is display circuit board that is attached to this board, right?

You are correct. That is the problem with the fridge. The display used to blink over so often but now it doesn't bother!

If only I could buy a spare board for it but they are obsolete.

[Rhothgar]

Re: Hotpoint FFA47X Fridge Freezer

i wonder why it has a reed-switch?

No idea but it is open. Don't know if it should be.

And thanks to everyone so far for helping me out with this. It is very much appreciated. I hope I can crack it and get it working again. If it doesn't stop buzzing SWMBO wants a new fridge.

[stj]

Re: Hotpoint FFA47X Fridge Freezer

No idea but it is open. Don't know if it should be.

yes, it should be open.
it closes when you put a magnet near it.

[Rhothgar]

Re: Hotpoint FFA47X Fridge Freezer

All measurements are taken in circuit (with components on board) at this point in time as the fridge needs to be kept live and I need to develop my desoldering skills. Any good videos out there? Watched a few on YouTube last night but they were fairly varied in quality.

I am currently using a Peak Atlas ESR70 to provide measurements in circuit.

C7 markings:
Top
N101083561 C
S4-X1M275V~ (Unsure about X though could be letter W)
Side
B81130 X2 MKP/SH
40/100/21/B
ENEC logo with a number 10 by side of it then RL in capitals written backwards with 250V~ under it and then cRL written backwards with 250V~ under it next to that

C13 markings:
Top
100n K 400V
373 MKT
Side
BC
R 0422

C29 markings:
Top
MK250
Cannot see any other markings on this cap.

C7 - Open Circuit or low resistance
C13 - 9.84uF ESR 2.3 Ohms
C20 - 400V 10uF (measures 9.53uF and ESR 4.4 Ohms)
RV1 - In-Circuit/Leaky ESR = 0.00
R30 - 10 Ohms
R100 - 27 Ohms

Other caps:-
Rating
C6 - 100V 2.2uF RMU (M)105degC (4R)
Measures
522.6uF ESR 0.61 Ohms

Ratings
C30, C31 and C33 - Teapo 50V 22uF SH105degC A3 04/04
C32 - Teapo 25V 100uF SH105degC A3 11/03

Measure
C30 - 0.92uF ESR >40 Ohms
C31 - 1.12uF ESR >40 Ohms
C32 - 88.48uF ESR 0.93 Ohms
C33 - 7.9uF ESR >40 Ohms

Rating
C28 - ELNA 10V 470uF CE105degC 0422 and a letter S in a circle RJH (M)

Measures
524.8uF ESR 0.19 Ohms

Rating
C26 - Teapo 25V 100uF SH105degC A3 11/03

Measures
88.22uF ESR 0.78 Ohms

Rating
C5 - Unknown RMU 100V 2.2uF SH105degC A3 11/03

Measures
88.22uF ESR 0.78 Ohms

Rating
C25 - Unknown KME 50V 22uF (M)105degC
Measures 24.6uF ESR 1.76 Ohms

[Rhothgar]

Re: Hotpoint FFA47X Fridge Freezer

As an aside, I have put my DMM on the copper windings of L2 and there is no beep? Surely there should be continuity?

Anyway, better plug it back in before food defrosts completely.

[Behemot]

Re: Hotpoint FFA47X Fridge Freezer

Oh yeah seems like just one way rectification than.

These are most likely bad, such high ESR is too high even for GP caps of that capacity (they yrae not so bad as JingHai caps so they should not have over 40 ohms; yet here you would nicely use ESR Micro which has range up to 200 ohms):
C30 - 0.92uF ESR >40 Ohms
C31 - 1.12uF ESR >40 Ohms
C33 - 7.9uF ESR >40 Ohms

These seem to be in parallel, if you have multimetr you can set it to diode/continuity tester (beeper) and check both appropriate sides, they should beep:
C28 - ELNA 10V 470uF CE105degC 0422 and a letter S in a circle RJH (M)
524.8uF ESR 0.19 Ohms
C6 - 100V 2.2uF RMU (M)105degC (4R)
522.6uF ESR 0.61 Ohms

[Rhothgar]

Re: Hotpoint FFA47X Fridge Freezer

Thanks Behemot.

How can I tell if a circuit in general is AC or converted to DC? This question is for this board but also in general so two questions really.

I am trying to find out how I can tell whether a capacitor is AC or DC? I suppose you could technically have a mix on a board depending on where it is located in the circuit.

[clearchris]

Re: Hotpoint FFA47X Fridge Freezer

Considering that you need the fridge in service, capacitors are cheap, and the caps are 11 years old, why are you even bothering to troubleshoot? Just replace them all, and if there are any relays on the board, Id replace those too.

As far as ac caps go, I havent ever seen a pcb mounted AC cap in an appliance. AC caps tend to be large and screw terminal or use quick disconnects.

[kc8adu]

Re: Hotpoint FFA47X Fridge Freezer

some are mounted near hot resistors.
replace all.
any lytic over 40 ohms esr is gone anyway.