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Wall wart Transformer troubleshooting

Newbee here. The wall wart charger for my rechargeable vacuum failed. It's rated 24VDC 250MA. I decided to open it up and see what's inside. Just a transformer, a capacitor and 4 zener diodes. Very simple circuit. Anyways I made an educated guess that the capacitor had failed, so I replaced it. Still doesn't work. I took out one of the diodes and checked for continuity, one way go the other no go, I assume it's ok and so are the rest. That only leaves the transformer, so my question is how do I check transformer function? Can I use an oscilloscope to check the transformer output? I am also wondering if a scope can be used to look at line voltage directly (stick the probes in the wall plug-hey I am just an amateur). Tnx

Reply to
Taz
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A simple voltmeter on the secondary of the transformer will tell you. Be careful not to make contact with the primary.

Reply to
Meat Plow

The thermal fuse looks like a small glass resistor in most cases, but will read open-circuit in both directions if it has failed. You ned to look at the secondary transformer voltage on the transformer side of the thermal fuse to be sure it is the fuse that is defective, not the transformer.

Unplug the transformer and check resistances also. If you measure the line side resistance, it should be in the range from 10 -30 ohms, more or less. The secondary resistance should be about 1/5th that amount, as a rule of thumb.

The diodes are probably arrnaged as a full wave bridge.

H. R. (Bob) Hofmann

Reply to
hrhofmann

Wrong already.

Why did you think they are ZENER diodes ?

Graham

Reply to
Eeyore

I bought a dozen eggs the other day and the container is leaking egg. I took out one of the eggs and checked it for structural integrity and it was fine. I assume it's ok and so are the rest. So where is the leak?

--
          If you really believe carbon dioxide causes global warming,
                          you should stop exhaling.
Reply to
clifto

And the student was enlightened.

--
          If you really believe carbon dioxide causes global warming,
                          you should stop exhaling.
Reply to
clifto

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