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Old 3rd Apr 2015, 1:30 pm   #19
Dekatron
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Join Date: May 2009
Location: Linkoping, Sweden
Posts: 953
Default Re: AVO VCM163 - Some faults I have had

Hi Graham,

Thank you for the file.

Avo says that the transformer voltages should be measured at 240V RMS to get proper readings, this is probably due to that higher voltages will affect the magnetisation in the core. The only thing I know is that the core will be saturated quite easily on these and that affects the sine wave of the output voltage a lot. The specification sheet I have has been amended and is the second revision, but there might have been more which I am not aware of.

I've usually seen lower voltages than the rated ones when measuring the transformers at 240V RMS, but that has almost always been due to the tip of the mains voltage not having a proper sine wave form but a kind of slanted tip. When measuring the voltages with a pure sine wave inverter they have always been within tolerance. So if you get any readings that doesn't match up you should use a scope to see what the mains voltage as well as the output voltage looks like - don't forget to use an isolating transformer for the scope though or you might make a short circuit.

I just had a look at my photos of my first VCM163, the one I reverse engineered, and the capacitors are connected from pin 6 to pin 15, 19, 23 and lastly to 25, that is also how all three of my VCM163s look.

/Martin
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