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Old 04-27-2017, 05:20 AM   #721
jamesbr
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Join Date: Mar 2017
City & State: Mount Waverley
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Wink Re: Samsung Syncmaster 245BW

After loosing screen backlighting on my samsung 245B I found one winding of this driver transformer open circuit.

Using epoxy thinners to weaken the notorious goop I was able to tease out the broken wire and solder a thin copper wire from a stripped flexible onto the winding end and back to the post.

Going again!

If you have a signal generator that can produce a 100kHz square wave of a few volts from a 50 ohm output you can put a test winding of say 5 turns on the outside of the existing windings.

Energise one of the working windings (almost zero ohms) and use an oscilloscope to look at the voltage on the energised winding and compare the volts on the test winding. This can give you a turns ratio. You can then remove the faulty winding or wind a new one over the outside.

The voltage waveform should be approximately square. If it is reduced to a short spike then there is probably a shorted winding.

If anyone is interested I will do tests and post oscilloscope records.
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