Strange DC offset on Aleph 3

Dukja · 03:59 AM

I just finished testing of my recent built DCB1 and was about to connect it to my Aleph 3 and found out something strange about A3's DC offset.

Before I turned on A3 with no input and no output connected, I measured about 1.5Vdc of speaker posts.

This dc volt was there even when I disconnect power cord. I realized that it may be the voltage held by power filtering caps. After shorting each channel with a 10 ohm resistor, the dc volt was gone.

If I don't bleed the dc volt, the dc volt can stay there for more than a day. But as soon as I powered up A3, the dc offset dropped to about 30~40mV.

This is new to me, so I didn't resume the DCB1 trial and want to check with you guys to see if it is normal. My guess was that the dc volt should disappear if either some bleeding resistors were crossing the power caps or if the speaker was connected. The charges in the caps would just short out without hurting speakers. But since I have no bleeding resistor and no load connected, the discharge of power caps (why shows on speaker post) "looks like" a dc offset??

Thanks for you help to solve this mystery to me.

(I did do the total recap on this A3 and noted here)

Zen Mod · 4th April 2012, 08:28 AM

stay cool

Dukja · 12:29 PM

So it was what it suppose to be? Nothing to worry about?

I saw my vintage Pioneer receiver has bleeding resistor, but I didn't see any for my A3. Is it good idea to put one or some on?

Thanks!

Zen Mod · 4th April 2012, 01:40 PM

spk will bleed that

Dukja · 4th April 2012, 02:45 PM

Thanks a lot ZM! You are the great help

as usual!

And I haven't figure the best way to add heatsink yet. I'll post the photo of my A3 after that.

4th April 2012, 03:54 AM	#1
Dukja diyAudio Member Join Date: Sep 2011 Location: Oklahoma, US	Strange DC offset on Aleph 3 I just finished testing of my recent built DCB1 and was about to connect it to my Aleph 3 and found out something strange about A3's DC offset. Before I turned on A3 with no input and no output connected, I measured about 1.5Vdc of speaker posts. This dc volt was there even when I disconnect power cord. I realized that it may be the voltage held by power filtering caps. After shorting each channel with a 10 ohm resistor, the dc volt was gone. If I don't bleed the dc volt, the dc volt can stay there for more than a day. But as soon as I powered up A3, the dc offset dropped to about 30~40mV. This is new to me, so I didn't resume the DCB1 trial and want to check with you guys to see if it is normal. My guess was that the dc volt should disappear if either some bleeding resistors were crossing the power caps or if the speaker was connected. The charges in the caps would just short out without hurting speakers. But since I have no bleeding resistor and no load connected, the discharge of power caps (why shows on speaker post) "looks like" a dc offset?? Thanks for you help to solve this mystery to me. (I did do the total recap on this A3 and noted here) Last edited by Dukja; 4th April 2012 at 03:59 AM.

4th April 2012, 08:28 AM	#2
Zen Mod diyAudio Member Join Date: Jan 2003 Location: ancient Batsch , behind Iron Curtain	stay cool __________________ my Papa is smarter than your Nelson ! tnx to clean thread ; Cook Book ; PSM LS Cook Book ; Baby Diyaudio FORUM ; Mighty ZM's Bloggg;I'm dumb

4th April 2012, 12:25 PM	#3
Dukja diyAudio Member Join Date: Sep 2011 Location: Oklahoma, US	So it was what it suppose to be? Nothing to worry about? I saw my vintage Pioneer receiver has bleeding resistor, but I didn't see any for my A3. Is it good idea to put one or some on? Thanks! Last edited by Dukja; 4th April 2012 at 12:29 PM.

4th April 2012, 01:40 PM	#4
Zen Mod diyAudio Member Join Date: Jan 2003 Location: ancient Batsch , behind Iron Curtain	spk will bleed that __________________ my Papa is smarter than your Nelson ! tnx to clean thread ; Cook Book ; PSM LS Cook Book ; Baby Diyaudio FORUM ; Mighty ZM's Bloggg;I'm dumb

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4th April 2012, 02:45 PM	#5
Dukja diyAudio Member Join Date: Sep 2011 Location: Oklahoma, US	Thanks a lot ZM! You are the great help as usual! And I haven't figure the best way to add heatsink yet. I'll post the photo of my A3 after that.

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