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Old 1st Feb 2007, 6:18 pm   #6
Mike Phelan
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Join Date: Nov 2003
Location: Near Leeds, West Yorkshire, UK
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Default Re: Cracked LOPT Core

Quote:
Originally Posted by Heatercathodeshort View Post
I have discovered that large numbers of vintage flyback transformers suffer from 'core saturation' resulting in the width and eht reducing say after 30 minutes use. I intend to investigate this during the coming months. Regards John.
Probably worth moving this, John, when you do this.
This may have some bearing on it, and I am sure you have seen this many times!

The DC feed chokes, sometimes called desaturation chokes in the Philips G6 LOPT, failed regularly, giving lack of width, and Philips replaced them with a larger diameter ferrite core.
We investigated those that failed, and though there were no shorted turns at all, the ferrite core had a much lower resistance than a new one (cannot the remember values we found).
Could this be the same reason as your old LOPTx symptoms?

For an explanation for others, the choke was connected across the PY500 cathode and PL509 anode and carried the entire PL anode current giving the LOPT some relief.
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