Must unplug and replug power to make Cooker Hood / Kitchen-Fan work

[carlsweden]

Problem:

Nor the fan nor the built-in spotlights will work. Then I unplug the power plug, wait for 5 min, and re-attach it to the power socket. Then both fan and spotlights work when switching them on using the normal buttons on the cooker hood. But after switching them off using the same buttons, and then trying to switch them on again, they will usually not work until I again detach and re-attach powerplug as described above.

When looking and smelling the circuit board I do not see anything out of the ordinary.

Question:

Do you have any idea what the problem may be? If so, is it something I can fix myself? If so, how?

Would it be a high chance of solving the problem by ordering a new circuit board from the manufacturer? (Circuit board (excluding transformers) costs 150 euros. A complete new cooker hood costs 400 euros)


Manufacturer:

Franke (The actual brand is Cylinda, but on the inside it says Franke Futurum)

Model:

Cylinda Sunda RF, but I believe the insides is the same as Franke’s model: F600 60 RF Franke.

Year: 2007

I attach PDF with an electrical diagram and photo of circuit board on page 3.

Any help is much appreciated.

Thank you!

Carl

 

[kellys_eye]

The lights are powered directly via a transformer and have no other intermediate controllers so the fault must be the transformer.

If it is fitted with a thermal overload it may be the reason for the problem. Check that you have the correct wattage lights fitted - anything higher than the manufacturers specified wattage and a thermal trip could be instigated.

Have you changed the lighting recently? Made any other changes/modifications?

 

[73's de Edd]

Sir Carl from Sweden . . . . .

If being a "sophisticated /involved" problem, it will involve the non existant . .as to date . . . actual schematic of the GREEN board circuitry.
Prior to seeking that out . . . . it sort of suggests of a possibility of a power loading problem.
If being the 12V halogen bulbs . . . and suspecting them to be the common bi pin contacts and peanut quartz envelope . . .is there a chance that one/ or / they might have accidentally received a slightly higher wattage lamp replacement ?

Looking at the fan wiring thereby, assuming the fan motor at the bottom as being a single speed option, with push on connector J0 being its relay related power on/off source.
Is there a possibility of 14 years of accumulated cooking grease grunge, having loaded it down and it now is pulling more wattage than should be normal ?
In power off . . . AC power unplugged . .or breaker off . . . condition, access the blade / impeller to hand spin and evaluate for its free spinning.

First evaluative test might be to duplicate your two fault conditions mentioned by initially unplugging connector J0 and seeing if those same two testing conditions you speak of being experienced, are unchanged.
Then replace J0 to then be able to unplug the bottom halogen lamp that only has 2 wires to it.
If its being a naked quartz glass lamp . . . don't get finger grease on the bulb exterior in handling.
Then redo the test.
If these have no effect then we move to the GREEN control and relay board.

FIO . . . . .
For the peanut gallery spectators . . . "Brytare" ? ? ? . . . . pushbutton switch panel.

Thaaaaaaaasit . . .for now . . .

73's de Edd
.....

 

[carlsweden]

Thank you so much Kellys_Eyes and 73's_de_Edd for trying to help me with
this!

I bought this for my mums 60 year birthday several years ago, and the price of a new one is 2 weeks salary for me, so I soo very much appreciate you guys trying to help me. Thank you!


I have made more detailed testing based on your questions. Below I write the results.


How it used to work before problem started:

The cooker hood has 5 touch-buttons (photo 1) that connect directly to the circuit board via a ribbon conector.

1 button for the spotlights. 4 buttons for the 4 different fan-speeds.

When pushing a button the first time, it makes something (I assume it’s the relays) on the circuit board make a “clicking”-sound, and then the function that belongs to that button is initiated (for example lights go on if it’s the light button).

The second time the button is touched; it again makes the clicking sound, and stops the function that corresponds to that button (for example switch off the lights).


How it works now after the problem appeared 2 weeks ago:

1. If I plug in power supply and wait without pushing any buttons for 1 minute or more, nothing works when I finally push the buttons.

2. If I plug in power and within seconds push one of the buttons (light or fan), it will work.

a. If I then switch off the function, then I will not be able to switch on any function without first unplugging and replugging powercord. (Even if I only ran the fan or had the light on for 2 seconds)

3. While having light on, I can switch the fan on and off and switch fan speeds as many times I want without malfunction.

4. While having one fan speed on, I can switch light on and off as many times I want without malfunction.

a. However, if light is switched off, and I have one fan speed switched on and working, then if I push the button for another fan speed, then everything will stop working (each speed-change involes pushing the fan-button that corresponds to that speed and have the corresponding relay “clicking” sound.

5. Sometimes, when I push the button for fan speed number 2 (after having disconnected power just before to make it work), the light will come on at the same time without me pushing the light button. This happens maybe one time out of 4 tries. This never happened before the other problems started.

6. Above results do not change when I try different power outlets, and I have verified that the Halogen spotlights do not exceed the max Effect (20W). Also, the fan has been regularly cleaned inside and appears to run smoothly.

7. To reply to 73s_de:Edd's suggestions, I tried removing the Halogen lightbulbs but the fan still had the same issue. Tried to disconnect fan wire (J0 wire in electrical diagram), but lights still had the same problem

Questions:

1. Is there anything I can try to fix the problem?

2. Is there a high probability of resolving the problem by buying new circuit board from manufacturer? (cost 150 euros).

 

[KJ6EAD]

After reading your first description, I thought a PTC resettable fuse in the fan or one of the transformers was being tripped and reset and I was going to suggest the same divide and conquer diagnostic method that Ed did.

After reading your second very thorough description of symptoms I suspect the PCB, specifically the microprocessor, is thermal cycling but there's still the possibility that a transformer is overheating. I suspect the processor because the 5-minute reset time would be sufficient for it but probably not for a transformer. I also don't believe any of the other components on the PCB are likely to have internal thermal protection though it's possible. All of my speculation about board components is moot anyway since component level repair is not an option for you.

I believe board replacement is indicated but I'd like to see a test of the transformer outputs to be more confident.

 

[kellys_eye]

The push buttons, being located ABOVE the cooking area, may have crud inside them that is affecting their operation. Can you dismantle the button unit enough to see inside and check for dirty contacts?

If a replacement button panel is available it may be cheaper than the circuit board BUT there are test and checks we can make to eliminate one or the other before laying out any money.

If you can blow cold air over the transformer/circuit board whilsst testing it and it keeps working then there is an issue with the main circuit board.

If you can find the individual wires for the push buttons and disconnect them, making the contact by simply shorting the correct pair(s) to establish the required function (or not!) we can eliminate the switches as a source of problem.

 

[73's de Edd]

Sir carlsweden . . .

Your selective disconnects of the lamps and then the fan seems to signify neither lamp overload or motor loading to be at fault.

NOW

Go to this site:

http://www.cylinda.se/produkt/kok/flaktar/9004341#

Play the top right . . . . . EASYCLEAN.
This relates to two aspects of your unit, the first part is being the two very-very easily accessible filters on the unit.

The second aspect is the then accessible main fan assembly, of which there are two different
filters in that pull down fan assembly which is not so easily done by the two go-go girls . . .SINCE . . . that next degree of complexity, requires Mamma Cass to pull down the fan module and remove its filters to clean them.
Have you ADDITIONALLY done this fuller degree of cleaning ?
( Unless this unit sat in stock for awhile, it's parts codes relate to it being around a 2008 model. )
If so, and you have seen that "fan module " proper, look for the electrical connections that apparently are made as you either pull it down for access or put it back in its replacement. I am interested in knowing how many contacts are involved in its two male and female in connector matrii..
I am expecting MORE than two connections being involved, If it only had 2 connections, that would ONLY account for the two connections of the fan motor assembly.
If you had 2 more connections, that could account for a sensor feed backs connections .
If you had two more connections that could account for AC power routing to a high voltage electrostatic filtering precipitator, that is all being built within that self contained assembly.


I am thinking that your first fan position ? ? ? "E fan" ? ? ? might be relevant to Electrostatic fan, which might suggest of an electrostatic particle precipitator being built into that removable fan assembly. That would also involve a leakage sensor / detector in the unit that would be feeding back the state of cleanliness of that plate network, needing it to be free of carbonized / conductive particulate matter , if having gradually accumulated between the separate electrostatic plates /grids elements .
If these bad and ever worsening conditions have evolved and are now bleeding down the high voltage, the sensor feedback faults the 32 pin Atmel microprocessor and tells the system to shut own.

BTW . . . pass back the identifications on the 4 other interfacing IC's on the board, as I can only read the Atmel unit.
Also, I am rolling around in my mind, why the 6 power switching relays and having only an apparent 5 functions, UNLESS that 6th relay function, proves to be related to switching on the units suspicioned electrostatic cleaning / filtering function.

73's de Edd
.....

 

[Tha fios agaibh]

Just my 2 cents to some great suggestions;

Monitor the power supply with a voltmeter before/after your 5min reset fix to see if there's a problem there.
It's possible a ps component such as a zener diode is shorting out the supply. Unplugging it causes the capacitor to discharge and temporarily resets the faulty component when voltage drops.

The power supply should be parallel with that big capacitor and should be easy enough to check.

 

[Bluejets]

Brown (active) terminal top right 2nd photo...... burnt up.

 

[KJ6EAD]

Brown (active) terminal top right 2nd photo...... burnt up.

Good catch! That's J0, the motor common. I see heat discoloration on the metal but fortunately no damage on the solder side or at the wire crimp so it's evidence of excess motor current. I also see signs of heat damage at J4 which corresponds to the motor's highest speed (insulation meltback, ferrule rotated and solder fillet distorted). I'm back to wanting a finger test on the fan followed by voltage measurements on the fan transformer.

@carlsweden, is a replacement fan motor available? Can you solder? Would you ever want to?

 

[carlsweden]

@Bluejets: Thanks for the tip. I agree it looks burnt in the photo, but it is just some shadow in the light when I took the photo. In reality it is a bit crooked, probably from manual handling when I removed it to test.

@KJ6EAD: Thanks. When looking closer without the camera-lence in between, J4 looks fine. No misscoloration. Wire was just leaning different than the other wires when solded during manufacture. I also already done the fingertest and the fan spins very smoothly when spinning it using my finger. No replacement motor available, but hopefully that is not the problem. Yes, I've got solding gear and will happily solder


Anyone?
Someone gave me the tip to change the capacitor. I have bought a new one, but there is a sign on the new one that is not present on the old one. Could someone have a look at the photo and say if they are the same?
They are both 100uF and 50V, but the white strip by the negative lead is marked " - - - " on the old one, but marked " - < - " on the new one I bought.
Are they interchangeable, or are they different, given that one has the "<" sing and one does not?

Photo attached.

Thanks!

 

[Tha fios agaibh]

As I said, very power supply.
Replacement cap is fine.

 

[KJ6EAD]

That's just a slight variation in marking style.