Background: Electronics novice, attempting stereo amplifier repair for educational purposes. Amp (Pioneer VSX-519V) blew when the input was removed while at high volume. Careful visual inspection does not sight any damaged components.
Am in the process of learning how to check a transformer.
The first two wires (black/blue) on primary have continuity, 1.7ohms, and 110v AC is present to the terminals that supply power to the transformer. There is no voltage present on any of the output terminals.
There is a second set of thick wires from primary coil: three wires (yellow-red-yellow) that have also proper continuity, but no voltage.
The secondary coils have two groups of three wires, and one group of six wires. Each group has continuity, and expected resistance's, but there is no voltage (AC) present anywhere.
There is no continuity between primary and secondary windings.
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Question: based on the above, does this transformer have a problem? I do not presently understand why all the other readings look good, but I have no AC voltage on any secondary windings.
UPDATE:
When the transformer is taken out and tested on the bench, it is fine. (that was a good lesson).
When the transformer is installed, something else is "tripping" and cutting power to the transformers primary coil during startup.
Best Answer
Your update tells me that your initial statement "...110V Ac is present to the terminals that supply power to the transformer..." is misleading. It implies that you are measuring at the transformer terminals - which you are not.
It is clear to me, that there is some safety circuit between the board terminals (were 110V comes in), and the transformer's input terminals.
Your safety circuit is detecting an unsafe condition and disabling power to the transformer primary terminals. There is nothing wrong with the transformer. Most likely, your power output transistors are shorted/blown, causing the safety circuit to remove power to the transformer.