Can SMPS transformer be tested with a oscilloscope

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BGAmodzX

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Hello everybody .

I have tried different ways to check Smps transformers like the induction meter and its Q parameter.

And read that the ring tester is not accurate to know if the transformer is shorted.


So i have an oscilloscope 20 mhz old school crt. Can this be useful for smps transformers.
 
Along with a pulse generator, probably.
What are the specifications of the transformer?
 
Ring testing is fairly effective for a SMPS TX, and will show if it's got shorted turns - such failures are usually fairly serious . I've repaired thousands of switchmode PSU's over the decades, and to be fair TX failures are pretty rare, there was only a small number of particular types which ever failed.
 

I get to repair some smps welders .
The problem is sometimes i cant find any problem on them so am left with the assumption of having a transformer problem.

I will unsolder one and upload it here this tranformer is switched using a viper20a smps Ic.
Now about the ring tester , does it test all types of smps transformers ?
 
Ring testing should work for any reasonable inductor, obviously the best thing to do is test a good one, and make a record of the result - then compare it to any potentially faulty ones later.
 
Is pulse generator necessary ? Is it possible to apply custom high frequency voltages to the transformer ?

You don't seem to understand what 'ring' means?, it's like striking a bell making it 'ring' - in the same way you apply a brief pulse to an inductor and watch the 'ring' on the scope. Historically it was done using the timebase output of the scope to create the pulse.
 
Ring testing should work for any reasonable inductor, obviously the best thing to do is test a good one, and make a record of the result - then compare it to any potentially faulty ones later.
Thanks . I will get one anyways .

So how about the lcr meter with the D ( dissiparion factor ) i have . Can i get the Q parameter just as good as a ring tester ?
 
A smps weld set, powered by a viper?, such Ic's were meant for standby supplies in consumer equipment.
Do you mean an inverter weld set with a auxilliary supply controlled by the viper chip.
I wouldnt be over concerned with the Q, an insulation test and a inductance test will give you a good idea on the trans.
Dont do an insulation test in circuit.
 
Thanks . I will get one anyways .

So how about the lcr meter with the D ( dissiparion factor ) i have . Can i get the Q parameter just as good as a ring tester ?

I've no idea, I've never used one, and I've no idea of it's capabilities.
 
Yes its for auxilliary supply .
That welder is dead with some burnt resistors near the viper . I will change them and see what happens.
 
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Its more than likely something has caused a fault in the Viper 20 chip than the transformer. Sugest you look up the data sheet on that chip. Also a picture of the actual circuit board would be of some help when asking people for help. Otherwise its all guess work.
 
Thanks everybody.
I think i will dig more on the pcb before buying a ringer , maybe its not a faulty transformer after all.

I will make a new thread in electronics repair section.
 
I suspect the burnt out resistor is the startup resistor, usually a few 100 k to 1 meg or so.
Could be because something else has failed & is preventing the supply from starting up.
 
I suspect the burnt out resistor is the startup resistor, usually a few 100 k to 1 meg or so.
Could be because something else has failed & is preventing the supply from starting up.

This may be the case mate thanks .

I have a similar pcb to copy the resistors values from even though not exactly the same layout , but i have a feeling they will boot the system up , had the same issue with a chinese one.
 
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