Hello,
Please can anyone help me identify this PCB transformer, shown in the attached photo. (The large blue transformer)
The Chest FREEZER Whirlpool AFG 605 DGT was bought in France.
It states on the blue transformer that the secondary output is 66V 2VA............but this seems very strange to me ?????
Very high voltage for a PCB board ?
Is it possibly 6.6v ???
The Borocco L7805 CV Voltage Regulator (which is downstream of the blue transformer) states that the voltage IN is between 7.5 and 35v
so the secondary output on the blue transformer does not make sense !!!
Any help would be much appreciated, especially on where to get a replacement transformer.
(From the markings on the transformer I can see it was made in Italy, but cannot make out the name of the Company)
Thank you
John
That is very reassuring. The majority of getting your units back in action will involve mechanical operations. And from what you have shown on the ETO images you can wield a soldering iron and squeeze a pair of pliers. Just remember the golden rule and never touch a unit that has more than 30V exposed.3) My skills are very limited. I am a qualified mechanical engineer, but I studied all this 40 years ago, and can't remember the majority of it all ! However I can determine faulty parts on a circuit board with a meter, and know how to replace them if I can find the parts !
Excellent4) Whirlpool Freezer : The reservoir capacitor has a voltage rating of 25V
No problem John5) Whirlpool Freezer : The 7.5v secondary would be much better than the 9v, thank you
Sounds hopeful in view of reason for the failure. One strong posibility is that the overvoltage supressors on the mains input side will probably have blown. But we can cross that bridge when we come to it.6) Whirlpool Freezer : The board is extremely simple. There is another board in the handle area of the freezer, which displays the temperature and allows you to control the freezer. I have taken this board out, and the components look fine and I hope there is nothing wrong with it.
Don't worry about that just draw a rectangle and note anything that is written on the component.We more or less know what the circuit should be.7) Whirlpool Freezer : I can try and trace out the circuit, but there are some components that I do not recognise !
The regulator is a standard component and freely available for about $0.50US, so teat it with care if you want to avoid further heavy expendature.8) Whirlpool Freezer : I believe the L7805CV, 5V, three-terminal regulator is OK (not blown), but I am not quite sure how to test it with my meter. Obviously until I repair the Blue transformer, I cannot see if it outputs 5volts. I have removed it from the circuit board, and there is a resistance between all three terminals (Terminal 1 (input), Terminal 2 (ground), Terminal 3 (5v output)) . Resistance between terminal 1 and 2, 1 and 3, 2 and 3. Not quite sure how this regulator works, so what the ohm readings should be, have no idea.
And you too JohnHope you all have a great weekend.
Great. ThanksI have photographed the circuit board, and the photos are attached.
Hmm. That means that the 100R resistor must be connected directly across the mains supply.The resistance R30 (5W100ΩJ) is on the input primary side of the transformer. It has blown. I replaced it hoping it would just be that, and the new one blew as well. (this was with everything left on the board).
Good. That black component is a bridge rectifier (as you said in the next post)On the output of the blue transformer............it passes directly into the little round black component (AM106 8024)......no idea what this is. From there it goes to the 5v voltage regulator with the capacitors on each side of the regulator.
RightThe Orange component is just a relay.
Sounds like a good approachInterestingly this freezer has remained running ...........the compressor runs all the time.
I believe the electronic part actually switches it off when it has reached the correct temperature (rather than the other way round, where it would switch it on)
That way if the electronics fail, as they have done, the compressor continues to run and you do not waste all the food in the freezer.
Certainly does.Does any of what I have written help you to make any assessment and recommendation please ?
The primary will be a relatively high resistance and the secondary will be a virtual short circuit. Can you measure the primary resistance and give me the reading from the multimeter? Can you also measure any secondary winding terminal to first one primary terminal and second the other primary terminal. The meter should show a complete open circuit on x10K.On the primary 250v side of the transformer, when I switch the ohms to x100 or x10k.......it shows a reading, but it should show continuity on a x1 which it does not. (The secondary coil shows continuity on x1 with no problem at all.)
I am not so sure.My conclusion.........The blue transformer is faulty on the primary coil side.
Could be an overvoltage protectors blown short, rather than the transformer.My only question is why would the R30 (5W100ΩJ) blow again on the normal 250v AC
The primary will be a relatively high resistance and the secondary will be a virtual short circuit. Can you measure the primary resistance and give me the reading from the multimeter? Can you also measure any secondary winding terminal to first one primary terminal and second the other primary terminal. The meter should show a complete open circuit on x10K.
Yes...........when I bought the new 5W100ΩJ ..........it was marked as a voltage regulator.............which I found odd for a "resistance" ??Could be an overvoltage protectors blown short, rather than the transformer.
If I have read the scale correctly on the analogue meter........it is 300 ohms. The light blue resistor (R32) which is next to the 5W100ΩJ is across the terminals of the Primary.In the meantime, can you measure the resistance between the printed circuit pads that previously connected to the transformer primary?
This is absolutely correct, it is.I think R32 is connected directly across the transformer primary.
That is the least I can do !It is nice to be helping someone that is prepared to help themselves and answer questions about their problem
I have taken another photo for clarity.I think I will be able to read the part number
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