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Testing small Transformer questions

I have a dead Ac/Dc adaptor. I'm busted it just to learns stuff. Im trying to learn how to test Transformers. This transformer says on it AMS10405 RG 1320F. I provide this to give all information, however Im not sure it matters much to my question.

I have so far removed from what I can gather are the Primary wires from the board. I assume they are because they are white and black and are literal wires going into transformer, as oppose to all the other connections which appear to be pins in the circuit board. I believe to properly test transformer you need to remove it fully eventually.

Here are my results with digital tester, When set to continuity, which appears to be (2) ohms setting. I get Beep and .002 Ohms. This seems to be very low ohms. I do find it difficult when any information on testing transformers says check with the data sheet. I'm sure someone will say sure here is the information its easy to find. Does .002 Ohms seem right for the primary.

Regards

Reply to
StevWolf
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Well thanks for your comments. You have encouraged me to dig into my meter a bit. Here are some results of my meter using some resistors I have.

100R set to 200 is 107 Ohms - Ok I guess 1 R set to Continuity says .974 Ohms - Yes seems OK. .39 R set to Continuity says .002 - thats close .39 set to 200 says 3.6 (which seems odd to me)

Importantly The manual for the for the meter seems to say that it will show continuity for anything less than 50ohms. Also while the meter has no information about the following, in the manual, when I set it to Continuity there is a little 2 under the decimal point, in the same way that it shows up when set to 200 for example with the respective 200 under the decimal. I asume that means 2 Ohms,

Sooo Im still trying to figure out if this transformer primary is bad? Maybe transformers which are basically two sets of winding in simple transformers dont have much resistance. I mean wire has loss but not a lot. ?? Again Im just trying to learn and understand.

Reply to
StevWolf

Well to try to answer questions,

100 ohm Resistor on continuity is .145 oddly .39 ohm Resistor on 200 scale is 7.6 again oddly Model of meter is MTP model 2322

The thing is its dashes ones Hope's when every website on testing says check data sheet, when they are so scarce if at all. And the numbers on the transformer so cryptic. I get that you need it but, they seem hard to come by so i assume you there must be charts to guestemate . I dunno. Regards.

Reply to
StevWolf

Yes the 100 ohm resistor shows 100 ohms on the 200 scale.

The .39 ohm resistor is a 2 watt orange, white, silver, gold.

The leads are in good condition.

Actually I have found several links for this meter. Here is one.

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Well as far as data sheets for transformers I find for me anyway, I do not find them as easy to find as common as other small parts, I mean you can find a data sheet on almost any old transistor, triac diac or component etc. But l find transformers less available. And if Chinese transformers are less likely then we are really out of luck as almost everything is made there.

Regards.

Reply to
StevWolf

Put that 100Ω resistor in series with the transformer primary and measure the resistance of both of them together. It should read 190Ω to 500Ω. I just pulled 4 random old style wallwarts and measured 90Ωs to 359Ωs. Is this an old style transformer and diode style or a lightweight switching type wallwart? Old style will only have a few parts maybe 6 or less. Is there a fuse that you can see? Old style you won't see it, new style it may or may not be covered with heat shrink tubing. Mikek

Reply to
Lamont Cranston

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