The resistance of the mains input / transformer primary is fine (in line with what I predicted/calculated)
Now, testing. I like to use the selection of 6V, 12V and 12V light bulbs that I have.
See this post
for the results I got.
But first, arrange the stripped ends of your output cable such that there is no danger of shorting anything out. For example, use a small screw terminal block (2A, 3A or 5A rating is fine). Or use a breadboard.
Before connecting to the mains, it is strongly recommended that you screw the lid on. Being safe is a wise thing to do.
Before powering up, connect you meter between the black and red wires, test on the 200 ohms range and confirm that you get a result of less than 2 ohms.
Next, connect each of your meter leads to each of the 7.5V AC outputs (wire colours green and white wires). Then power up. The meter should display a AC voltage of 16V AC or more. If this okay, that's the first test passed.
Next test each 7.5V AC output in turn (green, then white wires) to the red, then the black wires.
Now to test the 16V DC output, connect the meter between the yellow and black wires. Confirm that you have 16V DC AND the polarity
is correct (yellow positive).
Before disconnecting the meter, switch to the AC range (better still, if your meter has a mV AC range). Check that you get a low reading. As this will vary between meters and meter ranges, post up your result.
That will do for the no load tests