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Registered Member #1211
Joined: Fri Jan 04 2008, 11:20AM
Location: England - UK
Posts: 19
After running a 14" colour TV DC flyback for about 30mins, it HV output suddenly stopped completely. A quick check with the oscilloscope, showed all was well on primary side. Current consumption normal and steady - clean drain waveform, nothing out of the ordinary.
The Flyback was slightly warm, so I powered down the driver, waited 10 minutes & powered it back up. Magically, it was working again, but sure enough after 5 minutes it died yet again, silently.
My only thought is the components inside a DC flyback (diodes or capacitors) are heat sensitive ? There was no internal 'flashover' noise at all - just as though the secondary had gone completely open circuit.
I wasn't at all been thrashed, with a power input of 30V @ 1.8A using a single FET driver - 1.5" arc.
Just curious if this is a common problem, when a flyback is used for any length of time, at low power...
Registered Member #1211
Joined: Fri Jan 04 2008, 11:20AM
Location: England - UK
Posts: 19
Many thanks Matt
Prior to consigning it to the bin, I thought I'd do a bit of detective work and see if I could physically find the faliure point - out with the hacksaw, for what I thought, would be a very long & messy job...
Firstly, I carefully flush-cut off the screen & focus pots, & was suprised to find the track 'substrate' was a real mess - carbon deposits (black spots & lines) everywhere.
Going no further, I cleaned everything up with IPA & masked off the ceramic with PVC tape, making a neat job. 6 hours of continuous running later - not a glitch from it - amazing !
Probably just got lucky, but definatley worth investigating any suspected 'fried' DC flybacks in future.
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Intermitent Flyback Faliure - A Common Issue ?
