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[Closed] Flyback transformer testing and replacement
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gkmaia:
Can anyone help me diagnose this transformer or suggest a replacement?

Primary coil takes 5v and the feedback coil takes another 5v. I cannot get any output voltage so I assume it is faulty.

But it outputs to a 3v power regulator and a 1.5v power regulator so I suspect at the same 5v range.

As you can see by the photos. I get no output no matter what.

It has printed on it 3305 n181 and part number is S1673305 and unfortunately I cannot source a datasheet or the part.

Ian.M:
Its a transformer - it doesn't work on continuous DC, and if you put too much DC current through it you'll burnout a winding.

You need to know what sort of driver circuit its intended for then pulse it at an appropriate frequency to check it. However its almost never the transformer that's bad in low power low voltage (in and out) SMPSU circuits.  It will almost invariably be bad electrolytic capacitors, a blown semiconductor or occasionally an open-circuit resistor.  If the transformer is bad, it will usually show visible signs of distress, e.g. discoloured insulation from overheating or  cracked core.
gkmaia:
Transformer is T1 here on the photo. DMMV takes 5v.

DMMP on high 5v disables the circuit DMMP on low enables Q9 and takes 5v DC to the transformer.

That should output something in similar range. But it does not.

How you suggest I test this transformer. In the circuit it does not flow current.
Ian.M:
Ass you have it our of  circuit, start by checking the DC resistance of all its windings to confirm there are no open circuits.  Looking at the photos, from the dimensions and wire gauge one would expect resistances of  tens or hundreds of ohms.  Then check the transistors and the three diodes, and check R41-R43.  Check the ESR and capacitance of electrolytics C24, C26, C27 (or replace if you don't have an ESR meter and cap meter).  If no faults are found, put it back and measure the voltages in the part of the circuit to the right of T1 on the schematic, at each component pin and look for any discrepancies that may indicate a cracked track or dry joint.  If you've got a scope, check the signal at the base of Q9 when DMMP transitions from high to low to see if its attempting t start oscillating.
gkmaia:
I have removed Q10 and tested as a diode with my DMM. These are the results:
CB = 0.6v
EB = 0v
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