Completed aleph J --loud cracking sound on switch off

kp93300 · 25th November 2010, 03:00 PM

Hi All,
I need help to solve the problem.
I just completed the aleph J and noted a very loud cracking sound through the loudspeaker on switch off of the power supply.
It is very quiet on switch on and no hum at all.
The dc offset at output is less than 0.2 V but swing to about 1 to2 V on powering down.
I am using a CLC type of line filtering with about 200000UF caps. The L is wound on a EI transformer , diy type.
I also use about 11 uF of motor start non polar caps at the last stop.
Could this be the problem ?

appreciate all the help

kp93300

John Caswell · 25th November 2010, 03:07 PM

Hi kp9etc,
Sounds very much like arcing inside the power switch. Suggest you put snubbers/switch click suppressors across each section of the switch, consisting 0.1µF "Y" type capacitor in series with 100-120R resistor, or buy them ready made from RS or farnell.

John

Zen Mod · 25th November 2010, 03:24 PM

you can check John's idea with simple test - instead of using mains switch to power off amp - just plug power cord from wall .

John Caswell · 25th November 2010, 04:16 PM

Good idea Wilson, didn't think about that one, Capt. Mainwaring

John

kp93300 · 25th November 2010, 09:23 PM

Quote:

Originally Posted by Zen Mod

you can check John's idea with simple test - instead of using mains switch to power off amp - just plug power cord from wall .

To power off, I pull the power cord from the ac receptacle and the problem persisted.
kp93300

Zen Mod · 25th November 2010, 09:31 PM

pictures , please

kp93300 · 25th November 2010, 09:32 PM

Quote:

Originally Posted by John Caswell

Hi kp9etc,
Sounds very much like arcing inside the power switch. Suggest you put snubbers/switch click suppressors across each section of the switch, consisting 0.1µF "Y" type capacitor in series with 100-120R resistor, or buy them ready made from RS or farnell.

John

Will a 1/2 w resistor be ok ?
Can I use x2 rated ? Is the value of 0.1uF critical ? Smaller and larger value ?

thanks
kp93300

Zen Mod · 25th November 2010, 09:46 PM

considering this :

Quote:

Originally Posted by kp93300

To power off, I pull the power cord from the ac receptacle and the problem persisted.
kp93300

this will not help :

Quote:

Originally Posted by kp93300

Will a 1/2 w resistor be ok ?
Can I use x2 rated ? Is the value of 0.1uF critical ? Smaller and larger value ?

thanks
kp93300

problem is somewhere else , not in power switch

kp93300 · 27th November 2010, 03:49 PM

These are some pictures of the aleph j that I build.
The transformer is in another box.
The pre is J310 and Lightspeed clone as the attenuator.
hope i can find some pointers in troubleshooting this problem.

kp93300

kp93300 · 27th November 2010, 04:13 PM

Some more pictures of the build

25th November 2010, 03:00 PM	#1
kp93300 diyAudio Member Join Date: Mar 2007	Completed aleph J --loud cracking sound on switch off Hi All, I need help to solve the problem. I just completed the aleph J and noted a very loud cracking sound through the loudspeaker on switch off of the power supply. It is very quiet on switch on and no hum at all. The dc offset at output is less than 0.2 V but swing to about 1 to2 V on powering down. I am using a CLC type of line filtering with about 200000UF caps. The L is wound on a EI transformer , diy type. I also use about 11 uF of motor start non polar caps at the last stop. Could this be the problem ? appreciate all the help kp93300

25th November 2010, 03:07 PM	#2
John Caswell diyAudio Member Join Date: Aug 2006 Location: Berkshire UK	Cracking sound Hi kp9etc, Sounds very much like arcing inside the power switch. Suggest you put snubbers/switch click suppressors across each section of the switch, consisting 0.1µF "Y" type capacitor in series with 100-120R resistor, or buy them ready made from RS or farnell. John

25th November 2010, 03:24 PM	#3
Zen Mod diyAudio Member Join Date: Jan 2003 Location: ancient Batsch , behind Iron Curtain	you can check John's idea with simple test - instead of using mains switch to power off amp - just plug power cord from wall . __________________ my Papa is smarter than your Nelson ! tnx to clean thread ; Cook Book ; PSM LS Cook Book ; Baby Diyaudio FORUM ; BAF Forum & Gallery;I'm dumb

25th November 2010, 04:16 PM	#4
John Caswell diyAudio Member Join Date: Aug 2006 Location: Berkshire UK	Cracking Good idea Wilson, didn't think about that one, Capt. Mainwaring John

25th November 2010, 09:31 PM	#6
Zen Mod diyAudio Member Join Date: Jan 2003 Location: ancient Batsch , behind Iron Curtain	pictures , please __________________ my Papa is smarter than your Nelson ! tnx to clean thread ; Cook Book ; PSM LS Cook Book ; Baby Diyaudio FORUM ; BAF Forum & Gallery;I'm dumb


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