Transformer pins common to ground

[Ashroyer05]

I have a couple transformers on this board I'm working on and all but a couple (which I don't think are connected to anything) show continuity to ground. Surely not all of them should go to ground right?

[selldoor]

Re: Transformer pins common to ground

It may not matter - if they are not connected to anything in the transformer. It is just a locating pin soldered to help anchor the transformer.

[Ashroyer05]

Re: Transformer pins common to ground

Hmmm....I didn't know that. So if I suspect something from a transformer sounds like it's always a good idea to pull it and inspect. Thanks.

[budm]

Re: Transformer pins common to ground

On the secondary side of the transformers (I.E. two power supply with common ground ref on the secondary side) one pin of each transformer will be connected to the secondary side common ground, the other end of the transformer winding will feed for example the Anode of the rectifier Diode. So if you take the resistance reading on the Anode pin of one of the transformer to another Anode of the diode of that is connected to the pin of the other transformer, it will show low reading due to low DCR of the transformer winding.
Best way to learn is to draw up the schematic.

[selldoor]

Re: Transformer pins common to ground

As you say I think you have to suspect it first else it is a lot of effort. You dont say what
type of transformer main power?, inverter? Inverter ones often have 2 spare legs
some have more.

[budm]

Re: Transformer pins common to ground

Example Diagram.

[Ashroyer05]

Re: Transformer pins common to ground

Thanks bud I will study that. I can't get schematics on these things. I'm not sure what type of transformer. I've tested transformers in school but never had to identify ones in tvs. But most of the pins running from the transformers are in the same trace on the board and they all run to ground.