24 dB/Octave 2/3-Way Linkwitz DC on output after power cut - diyAudio
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Old 5th August 2005, 08:55 AM   #1
Calebay is offline Calebay  Denmark
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Angry 24 dB/Octave 2/3-Way Linkwitz DC on output after power cut

Hello

i build this 24 dB/Octave 2/3-Way Linkwitz from http://sound.westhost.com/project09.htm

i made it 3 way and i have changed all opamp for OPA627
it seems to be working just fine. but then today i acidently pulled the AC plug, from the filter while the amp was still on. 1 sec. later! a Bad sound! and smoke! from my new Neo3PDR



so i disconecntet the amp and mesured no DC on output when power on. but when i turn it off for 1-2 sec. 1-1.5volt DC on all output

How can i cure this??
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Old 5th August 2005, 09:00 AM   #2
sajti is offline sajti  Hungary
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Apply mute circuit on the end, with relay, or muting transistor. Another solution, to use stronger powersupply to keep the circuit up, untill your powermaplifier switch off.
And last but not least: Use coupling capacitor on the output of the filter

sajti
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Old 5th August 2005, 09:15 AM   #3
Calebay is offline Calebay  Denmark
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hmm but is it normal this DC after i cut the power?
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Old 5th August 2005, 09:20 AM   #4
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The DC could be caused by that the pos. and neg. supply fall at different speed
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Old 5th August 2005, 09:32 AM   #5
Calebay is offline Calebay  Denmark
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they drop at the same speed very close on my scope.


its fisrt after the supply voltage has dropped below 2volt. then i get the DC on the output
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Old 5th August 2005, 09:44 AM   #6
sajti is offline sajti  Hungary
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Quote:
Originally posted by Calebay
hmm but is it normal this DC after i cut the power?

Unfortunately yes. Most of the manufacturers use muting circuits on the output, to cut the DC during the ON/OFF period.

sajti
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Old 5th August 2005, 09:46 AM   #7
sajti is offline sajti  Hungary
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Quote:
Originally posted by Calebay
they drop at the same speed very close on my scope.


its fisrt after the supply voltage has dropped below 2volt. then i get the DC on the output
Just add series capacitor (1-10uF), and parallel resistor (100-200k) to the output, and You will never see this problem any more....

Sajti
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Old 5th August 2005, 11:17 AM   #8
Calebay is offline Calebay  Denmark
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okay did not know that

ill better put some capacitors in there then

tnx for the help
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Old 1st October 2005, 07:15 PM   #9
Calebay is offline Calebay  Denmark
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Hello

Iím back whit a new problem, worse i think.

My crossover has been working fine for a I think Ĺ a yeah. But just 5 minutes ago while playing music. A LOUD, VERY LOUD horrible sound, I donít believe my speakers can get any louder than that. Very nasty sound I believe it was between 60-3000Hz. it was only in the one channel, I ran over and turned it off. When I turned I back on it was gone. What can cause this? A bad solder join? Or a bad cap? Glad the speaker id not blow.

Hope someone can help
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Old 2nd October 2005, 04:59 AM   #10
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Sounds to me like a bad solder joint.......
Maybe a Gnd connection?
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