Does a mains transformer still use electricity if the item it is plugged into is switched off?

Either the mains lead has gone or the power switch is broken. Or something else faulty depending on what is there between the mains plug to the primary of the transformer.

depending on your level of electrical knowledge it may be possible to diagnose the problem.

First check the obvious - fuse in plug / distribution board - you would be surprised how many times this is missed.

Beyond this proceed at your own risk as mains voltages will be exposed.

If you open up the keyboard you can check the input voltage with a multimeter is arriving at the power transformer input.

There may be fuses on the transformer board - check these - DON'T FORGET TO UNPLUG FROM THE MAINS FIRST

Check the operation of the mains switch - these do fail over a period of time and your instrument is quite old now. Unplug from the board and test for continuity across the pins.DON'T FORGET TO UNPLUG FROM THE MAINS FIRST


If the above doesn't solve the issue then you have a more serious problem such as a power supply board failing or a problem on the main board - seek out a Yamaha service centre who might be able to help.

John,
If you have a multi meter then unpug from mains supply.With meter
on "ohms" range check the following:-
Fuse F501 (and F502 if mult-voltage model)
yellow to white on mains transformer this should show some resistance.If you have a mult-voltage model check
brown to gray and orange to white. Both should show some resistance, if not your mains transformer has an open circuit primary winding.....

there should be a small black box transformer wired into the ac cord
that goes to your standard plug
the transformer should then have wires going to your heating element
If someone has removed the transformer just order a 110vac to 12v 12 amp transformer and wire it in like you would a doorbell
when the transformer is working you should feel heat at the rear of your refrigerator at the heating element

Most portable devices have a thermal fuse built into the transformer instead of using traditional fuses. I suggest installing batteries to check if the radio will come on, if yes! the plug in ac power is the problem, if no! the main processor in the item is the likely cause and the radio should be replaced. If you unscrew the back and remove it, follow the plug in to the circuit board where the fuse should be located if there is none, the power transformer is fused on the inside, only option is to replace transformer, but not cost effective.

Hi
If picture and sound is Ok, and only this buzzing sound is heard from the back of the TV, It should be due to core soose of some ferrite cored transformers inside, especially to the power supply regulator board of the TV. Open the back cover of the TV and swtich it ON. Listeen very carefully which transfromer makes the buzzing noise. Just trouch and press the core of the transformer suspected with some non-cunductive material like glass rod, or a stick of dry wood. You can identify the transformer that makes noise by this way. After identifying the exact transformer; switch OFF the set, unplug it from mains socket, apply some "Super Glue" like fast boanding glue to the joint of core of that transformer. Allow sometime for the glue to set. This will solve the buzzing sound problem of your TV. OK

keep on your main switch. off all the lights fan and other electrical items, let that inverter get charge first

The main circuit board supplies ac power to the ignitor ( black transformer looking device) and the transformer increases the voltage that is supplied to the sparking device. Make sure the wires are connected to the sparking device and the ends of this device are approximately 3mm apart and that it is in the general position near the end of the nozzle. If you do not hear a "clicking" sound it could be the main board, wires or sparking device.

Check the flyback transformer for cause of the odor . If it is a cap look for a cap that is buldging at the top of it . The flyback is the transformer with the red lead going to the picture tube . You might see it is cracked or a tiny hole in it . Good luck

The transformer needs to be replaced. 120VAC to 15VAC. Take a look on amazon for it, here: Amazon com 15VAC transformers. Wish you best of luck.
Brust