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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc. |
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11th Aug 2023, 10:22 am | #1 |
Triode
Join Date: May 2023
Location: Epsom, Surrey, UK.
Posts: 34
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SMPS chopper transformer.
Can a chopper transformer be tested for shorted turns? Got a LOPT tester courtesy TV mag but would it work on above? Probably not.
P. |
11th Aug 2023, 10:27 am | #2 |
Dekatron
Join Date: Jun 2015
Location: Biggin Hill, London, UK.
Posts: 5,228
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Re: Don't know
I've used a ringing tester built from Television magazine to test chopper transformers. It seems to pick up shorted turns OK, as you might expect. After all, it just shows that the oscillations are heavily damped due to the energy absorbed in the shorted turn.
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11th Aug 2023, 12:40 pm | #3 |
Heptode
Join Date: May 2006
Location: Accrington, Lancashire, UK.
Posts: 978
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Re: Don't know
Might be related but I used to "ring" lopts. Just attach the two top connections to check line output transformers. If you got EHT on the primary you could assume the transformer was good, never let me down.
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12th Aug 2023, 10:44 am | #4 | |
Triode
Join Date: May 2023
Location: Epsom, Surrey, UK.
Posts: 34
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Re: Don't know
Quote:
P. |
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12th Aug 2023, 11:57 am | #5 |
Dekatron
Join Date: May 2010
Location: Greater Manchester, UK.
Posts: 18,727
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Re: SMPS chopper transformer.
To get this shot, I think I simply had one probe on the Y input and the other on the Cal output and connected them across the primary winding of the Loptx I was testing.
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17th Nov 2023, 11:06 am | #6 |
Triode
Join Date: May 2023
Location: Epsom, Surrey, UK.
Posts: 34
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Re: SMPS chopper transformer.
Applied ringing test to device as described ie:cal-winding-i/p.Acceptable trace obtained similar to above.
Power diode shorting on sec which I should've checked earlier.Could've saved ages.Ah didnae ken. Put it all back together & not a bad picture considering tube is 38,TX 100 series.Is this a record? A few other components want replacing sometime..... |
17th Nov 2023, 11:57 am | #7 |
Hexode
Join Date: May 2009
Location: Ryde, Isle of Wight, UK.
Posts: 421
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Re: SMPS chopper transformer.
That Diode was a common fault back in the day, was it D22, a BY298 memory fading.
Ken G6HZG.
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20th Nov 2023, 11:34 am | #8 |
Triode
Join Date: May 2023
Location: Epsom, Surrey, UK.
Posts: 34
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Re: SMPS chopper transformer.
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21st Nov 2023, 7:24 am | #9 |
Hexode
Join Date: May 2009
Location: Ryde, Isle of Wight, UK.
Posts: 421
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Re: SMPS chopper transformer.
Paul, thanks for jogging the memory
Ken G6HZG.
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21st Nov 2023, 9:10 am | #10 |
Moderator
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,920
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Re: SMPS chopper transformer.
All transformers can be tested by a ringing technique, though sometimes you may need to add a capacitor to get a ring frequency you can use. Interpretation might be best by comparison with a known good one. For RF transformers you need a fast-edged pulse generator and a fast scope or a TDR.
David
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