Problems with Rod Elliot's Project 05 (power supply)

lordvader · 22nd April 2003, 08:37 AM

Hi.
I've almost finished building a preamp based on most of Rod Elliots projects. I am, however, having trouble with the power-supply.

I did some testing with a 5W, 22Ohm resistor in series with the AC (before the rectifier), and was able to measure the +/- 15V on the outputs.

When I remove this resistor, the fuse blows. I'm using 500mA, quick-blow fuses, and my powersupply is a 16V, 1.5A AC powerpack.

Any help would be much appreciated. My electronic knowledge isn't the best (I skipped most of my EE lectures ...), so please excuse me if this seems a silly question.

trwh · 22nd April 2003, 08:52 AM

Hi lordvader,

Try slow blow or antisurge fuses instead. Maybe the inrush current from the 1.5A plugpack is enough to rupture the 500mA quick blow types.

See ya,
Tim.

jan.didden · 22nd April 2003, 10:50 AM

Most probably you have a massive supply cap in the preamp, that acts like a short to the poor power pack at switch-on. Since this is only a problem at switch-on, Tims's advice will save you, but negates the protection of the power pack. A better solution is to use say 1 or 2 ohms from the powerpack to the preamp supply caps and see if the original fuse stays up.

Jan Didden

lordvader · 22nd April 2003, 12:41 PM

Thanks for all your replies. I'll give them as shot as soon as I get some new fuses!

22nd April 2003, 08:37 AM	#1
lordvader diyAudio Member Join Date: Mar 2002 Location: n/a	Problems with Rod Elliot's Project 05 (power supply) Hi. I've almost finished building a preamp based on most of Rod Elliots projects. I am, however, having trouble with the power-supply. I did some testing with a 5W, 22Ohm resistor in series with the AC (before the rectifier), and was able to measure the +/- 15V on the outputs. When I remove this resistor, the fuse blows. I'm using 500mA, quick-blow fuses, and my powersupply is a 16V, 1.5A AC powerpack. Any help would be much appreciated. My electronic knowledge isn't the best (I skipped most of my EE lectures ...), so please excuse me if this seems a silly question.

22nd April 2003, 10:50 AM	#3
jan.didden diyAudio Member Join Date: May 2002 Location: Great City of Turnhout, Belgium Blog Entries: 6	PSU problems Most probably you have a massive supply cap in the preamp, that acts like a short to the poor power pack at switch-on. Since this is only a problem at switch-on, Tims's advice will save you, but negates the protection of the power pack. A better solution is to use say 1 or 2 ohms from the powerpack to the preamp supply caps and see if the original fuse stays up. Jan Didden

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22nd April 2003, 08:52 AM	#2
trwh diyAudio Member Join Date: Apr 2002 Location: UK	Hi lordvader, Try slow blow or antisurge fuses instead. Maybe the inrush current from the 1.5A plugpack is enough to rupture the 500mA quick blow types. See ya, Tim.

22nd April 2003, 12:41 PM	#4
lordvader diyAudio Member Join Date: Mar 2002 Location: n/a	Thanks for all your replies. I'll give them as shot as soon as I get some new fuses!