How does these transformers work?

[pilot125]

I'm trying to repair my ATX PSU and I'm sort of trying to follow the flow of current to see where it goes wrong. I was doing fine until came across with two transformers. I'm pretty sure the big one is supposed to output 12V and the smaller 5V. So I need to measure voltages of the primary and secondary parts of both to see if there's something wrong.



After some research, found two datasheets that seem to correspond to my transformers (not sure however):
https://pdf1.alldatasheet.com/datash...06-ERL35R.html
https://datasheetspdf.com/pdf-file/1204705/FPE/EE19/1

Despite having basic electronics knowledge, my experience is limited. I've only seen transformers with three or two pins each side. According to the datasheets, bigger has 14 pins and smaller has 10 pins. I'm confused. Can someone explain what I'm looking at?

[budm]

Re: How does these transformers work?

If Transformer has many windings the it will have more pins.
https://pdf1.alldatasheet.com/datash...06-ERL35R.html
So what is so confusing about the amount of pins the transformer has.
Since SMPS power supply runs at high frequency, typical DMM do not have high frequency bandwidth to be able to measure the high frequency AC.
Look up spec sheet of SMPS IC U3 to see how SMPS works.

[pilot125]

Re: How does these transformers work?

If Transformer has many windings the it will have more pins.
https://pdf1.alldatasheet.com/datash...06-ERL35R.html
So what is so confusing about the amount of pins the transformer has.
Since SMPS power supply runs at high frequency, typical DMM do not have high frequency bandwidth to be able to measure the high frequency AC.
Look up spec sheet of SMPS IC U3 to see how SMPS works.

Ok, so I won't be able to measure without an oscilloscope. Will find a workaround though, thanks

[budm]

Re: How does these transformers work?

1) What troubleshooting have you done so far? What is not working, 5V power supply? 12V?
2) You will need isolation transformer for the power supply if you are going to use the scope if the scope circuit gnd is connected to safety ground?
You do know about electrical safety when making measurement in the HOT DEADLY side of the circuit, correct?
3) You should study how SMPS works first before trying to troubleshooting the unit.
4) Did you at least look up the spec sheet of the IC as suggest? You should at least do that.

[pilot125]

Re: How does these transformers work?

1) What troubleshooting have you done so far? What is not working, 5V power supply? 12V?
2) You will need isolation transformer for the power supply if you are going to use the scope if the scope circuit gnd is connected to safety ground?
You do know about electrical safety when making measurement in the HOT DEADLY side of the circuit, correct?

1) Bridge rectifier working, after that there's two big electrolytic caps that are OK and then after some bits of circuitry (guessing PWM? now I remember reading the wave in the transformer would be like 60 kHz, so I should've known this) there's the transformers I previously wanted to take a measure.

2) Well I don't think I'm gonna mess with the transformers directly anymore (for now). I'll search for short circuits in the transistors just before them.
Thanks for worrying, but I'm extremely careful

3) Agreed. I've had an overview, it is simply hard to assemble everything quickly. Certainly I lack details, which are being picked up as I study my PSU.

4) Sorry, what IC is that? Name doesn't seem precise to me. Lots of diverging results in Google.

[pilot125]

Re: How does these transformers work?

Is this the IC? https://cdn.badcaps-static.com/pdfs/...d36f869dbc.pdf

[RJARRRPCGP]

Re: How does these transformers work?

Lots of diverging results in Google.

I lately found search engines other than Google to be worse for search results.

Hoping it's just a temporary setback...

[budm]

Re: How does these transformers work?

Is this the IC? https://cdn.badcaps-static.com/pdfs/...d36f869dbc.pdf

Is that the number as printed on top of U3? That spec sheet is not for U3, U3 looks to have built-in power MOSFET for driving the small transfomer directly.