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Toroidal Transformer rising current on amp10b!
Toroidal Transformer rising current on amp10b!
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Old 25th October 2008, 06:44 PM   #1
Matthew P. is offline Matthew P.  Canada
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Join Date: Oct 2006
Default Toroidal Transformer rising current on amp10b!

Hi there,
I was hoping someone could help me. I'm building my second tripath amp - the 41hz amp10b and I believe the soldering went very well, I tested the 5v with a walwart and got the 4.95v. Next I hooked up the toroid (AN-3220) and got the relay working, and even got sound. Then the relay started clicking on and off repeatedly. I believe this is from what happens at the AC inputs. I test the AC inputs and the current rises slowly from what it should be (20v) to over 24-25 volts.

The tranny, IEC receptacle, amp, etc.. are mounted presently on a piece of wood, so its all isolated. I have the toroid primaries wired for 115v (twisted red with red, black with black). On the live lead I have a 60W light bulb and a fuse hooked up in series and the light flashes briefly and goes off as it should. I have the secondaries (green and blue twisted and going to the AC inputs as per instructions on the board).

So would anybody have any idea why the current is rising? Does it have to do with something internal to the amp, or to the tranny?

Thanks a bunch for any help or suggestions people would have.
Best Regards,
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Old 28th October 2008, 08:49 PM   #2
gpapag is offline gpapag  Greece
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Toroidal Transformer rising current on amp10b!
Hi Matt
The relay may go off due to:

over or under DC voltage (measure DC Voltage and see if it is within the limits set by the over/under voltage setting resistors )

excessive dc offset at the output (measure and trim-off dc offset)

excessive current at the output (check for any shorts)

You would like to do these tests with no input signal (better, inputs shorted to ground) and dummy load on the output.

You are writing "current rising". I believe you mean "voltage rising", as you measure it in Volts.

What is the nominal AC voltage of your x-former secondaries (and what is the amperage rating)?

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