NAD 3020 problem

vubkevin · 10th December 2007, 10:50 AM

I have a problem with my NAD 3020a , it seems that the woofer on the left channel moves bigger than the one on the right channel. but both sides seems to have the same volume.
I have tried, the problem comes from the pre-amp part, what could possibly cause this problem?

Mooly · 10th December 2007, 11:12 AM

Hi, Does it sound wrong. Lacking in Bass etc. What tests have you done. Are you sure it is Pre-Amp. Are all inputs affected.
Regards Karl

vubkevin · 10th December 2007, 01:04 PM

yep, less bass than the other channel, I've tried to connect the pre amp out to another amp. so I know it's the pre amp's problem

Mooly · 10th December 2007, 04:44 PM

Hi, It can only be a capacitor that has gone low in value.Have you got a schematic ? IF you have no test equipment get a 47mfd 63volt capacitor (or anything thereabouts 10 mfd 100mfd it dosent matter) and bridge any coupling caps in the Pre-Amp one at a time (Keep volume low and connect right way round).If you have circuit can tell you which ones to check.Just a thought, nothing like an open circuit pot on the tone controls ?
Regards Karl

vubkevin · 10th December 2007, 09:55 PM

hi, yes, I have the circuit , which one should I check?

vubkevin · 10th December 2007, 09:59 PM

rdf · 10th December 2007, 10:14 PM

Hi vubkevin. For 6 electrolytic caps just replace them all and enjoy it for another 20 years. I recently did the same to a Rotel RX-980 bought cheap and it was worth the effort. Don't forget the PS caps, electrolytics have advanced spectacularly since that amp left the showroom. Worth the minimal cost.

vubkevin · 10th December 2007, 10:22 PM

which 6 electrolytic caps should I replace? just want to narrow where is the problem, I donno how to read the circuit, and donno which cap effects the bass

rdf · 10th December 2007, 10:41 PM

C401, C402, C409, C410, C417 and C418. If you're new to this make sure the negative sign on the replacement caps are in the direction as the ones you remove. Is the bass problem only on records? The schematic you posted is for the phone pre.

vubkevin · 10th December 2007, 10:45 PM

oh? then does anybody has the pre-amp schematic for NAD3020a?

10th December 2007, 10:50 AM	#1
vubkevin diyAudio Member Join Date: Jul 2007	NAD 3020 problem I have a problem with my NAD 3020a , it seems that the woofer on the left channel moves bigger than the one on the right channel. but both sides seems to have the same volume. I have tried, the problem comes from the pre-amp part, what could possibly cause this problem?

10th December 2007, 10:14 PM	#7
rdf diyAudio Member Join Date: Jun 2004 Location: big smoke	Hi vubkevin. For 6 electrolytic caps just replace them all and enjoy it for another 20 years. I recently did the same to a Rotel RX-980 bought cheap and it was worth the effort. Don't forget the PS caps, electrolytics have advanced spectacularly since that amp left the showroom. Worth the minimal cost. __________________ Ears aren't microphones.

10th December 2007, 10:41 PM	#9
rdf diyAudio Member Join Date: Jun 2004 Location: big smoke	C401, C402, C409, C410, C417 and C418. If you're new to this make sure the negative sign on the replacement caps are in the direction as the ones you remove. Is the bass problem only on records? The schematic you posted is for the phone pre. __________________ Ears aren't microphones.

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10th December 2007, 11:12 AM	#2
Mooly diyAudio Member Join Date: Sep 2007	Hi, Does it sound wrong. Lacking in Bass etc. What tests have you done. Are you sure it is Pre-Amp. Are all inputs affected. Regards Karl

10th December 2007, 01:04 PM	#3
vubkevin diyAudio Member Join Date: Jul 2007	yep, less bass than the other channel, I've tried to connect the pre amp out to another amp. so I know it's the pre amp's problem

10th December 2007, 04:44 PM	#4
Mooly diyAudio Member Join Date: Sep 2007	Hi, It can only be a capacitor that has gone low in value.Have you got a schematic ? IF you have no test equipment get a 47mfd 63volt capacitor (or anything thereabouts 10 mfd 100mfd it dosent matter) and bridge any coupling caps in the Pre-Amp one at a time (Keep volume low and connect right way round).If you have circuit can tell you which ones to check.Just a thought, nothing like an open circuit pot on the tone controls ? Regards Karl

10th December 2007, 09:55 PM	#5
vubkevin diyAudio Member Join Date: Jul 2007	hi, yes, I have the circuit , which one should I check?

10th December 2007, 09:59 PM	#6
vubkevin diyAudio Member Join Date: Jul 2007

10th December 2007, 10:22 PM	#8
vubkevin diyAudio Member Join Date: Jul 2007	which 6 electrolytic caps should I replace? just want to narrow where is the problem, I donno how to read the circuit, and donno which cap effects the bass

10th December 2007, 10:45 PM	#10
vubkevin diyAudio Member Join Date: Jul 2007	oh? then does anybody has the pre-amp schematic for NAD3020a?

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