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Old 28th November 2005, 01:05 PM   #1
Michele is offline Michele  Italy
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Default Fortè Audio 1a

I have a problem with 1 of the 2 Fortè Audio I have. Sometimes the transformer make a noise (a sort of zzzzzzz), must I change it or can I make something else? Thank you
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Old 28th November 2005, 03:27 PM   #2
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I picked up a Forte 1A not long ago and have also noticed that the transformer buzzes/hums. It is fairly loud when first switched on, but settles to a lower volume after a second or two. I don't think this is anything to worry about, but someone else may have a more decisive opinion on this.
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Old 29th November 2005, 02:21 AM   #3
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Like most other toroids, the transformer hates DC on the line.
Try running it with a large capacitor in series with the line. I
usually use two big electrolytics back to back (say + to +)
with a power diode across each one to keep them from getting
too much reverse bias.
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Old 29th November 2005, 01:07 PM   #4
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Quote:
Originally posted by Nelson Pass

. . . large capacitor . . .
. . . reverse bias . . .

Hi, Nelson

After having moved to a new apartment recently, I get somewhat DC from the wall AC power.

1. How large is large . . . ? 1,000uF or 10,000uF?
2. Is the small reverse bias to avoid the re-anodizing problem?

Thanks.

Regards
jH
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Old 29th November 2005, 02:01 PM   #5
Zen Mod is offline Zen Mod  Serbia
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tested ,somewhere from net
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Old 29th November 2005, 06:48 PM   #6
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I think you need to reverse the diodes (or the polarity
of the caps) in that diagram. Also, it's wise to place a
bleed resistor, say 100 ohms @ 3w or so, across the diodes.
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Old 29th November 2005, 08:41 PM   #7
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Now I clearly understand why the voltage rating of the cap doesn't matter. Choky's diagram provides too much reverse bias.

Regards
jH
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Old 29th November 2005, 08:57 PM   #8
Zen Mod is offline Zen Mod  Serbia
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mea (maxima) culpa!

hehe-when I tested that circ,I didn't have schmtic near me,and made it right from my scull.......
obviously -in right way-but I didn't double checked that pic........
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Old 29th November 2005, 09:06 PM   #9
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Old 29th November 2005, 10:02 PM   #10
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Using the leftover, I'll try this for my F1.

Regards
jH
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