NAD 304 Repairs

Treefingers · 27th July 2005, 12:16 PM

First post here.

I have a NAD 304 that i use for music while i try and finnish an amp based on a gainclone design. I turned this on yesterday to find the light was staying on red, and a smell of burning comming from it.

Searches have shown me that Some resistors should be changed, specificly R333 and R334 to 1 Watt. I have checked the resistors and they seem fine, but am about to change them anyway as i have some spare 1 watt resistors lying around.

are there any other idea's as to what is causing this - has anyone else experianced problems like this and it not been caused by the Resistors?

Thanks

Matthewong · 27th July 2005, 02:18 PM

Do u have the schematic diagram, I need to refer to it first bfore I can tell you anything.

Leolabs · 27th July 2005, 02:57 PM

Where are those resistors located???

Treefingers · 27th July 2005, 03:24 PM

UPDATE:

have replaced resistors, it still isn't turning green. any other ideas?

Treefingers · 27th July 2005, 03:24 PM

I am afraid not.

I am still trying to find something visably damaged, but it dosn't seem to be that easy. my searches showed me a few people had the diagram, so im going to try and email them to get it

Matthewong · 27th July 2005, 04:07 PM

I'm not able to help you since you only give me very little detail. But I can tell you that your NAD 304 protected mostly some components malfunction or spoiled. You better check that whether the transistors is still in good condition or not, then check v+ and v- voltage.

Treefingers · 27th July 2005, 06:26 PM

Thanks for your help so far, if there is any infomation you need please just ask - i will try to help as much as i can.

I have no idea what part of the circuit is damaged, i would assume it is not the powersupply or the LED would not light up at all. But other then that i have no idea.

I noticed a Fuse has slipped partly out of it's holder, as the amp worked last time it was on, could the damage be from the amp being dropped, i am guessing i should try re soldering all the joints?

Leolabs: The resistors are located neer the main transistors and heatsink. There are also a second pair that seem to be part of the pre amp which are supposed to be replaced if they are not 1 Watt items, i have checked both and they are the correct values.

Treefingers · 28th July 2005, 11:14 AM

I have obtained and uploaded the schematic here

Matthewong · 28th July 2005, 04:51 PM

I think you need to check whether there is any voltage go into the pre-amp and power amp board. Because last time my friend were using NAD amp also and faced the same problem, but he finally found out that there is no supply voltage to the power amp.

Treefingers · 28th July 2005, 08:29 PM

Okay, the NAD 304 is capable of being bridged - would i be able to check if the pre amp is producing any power by checking this connection in relation to the phono ground?

27th July 2005, 12:16 PM	#1
Treefingers diyAudio Member Join Date: Jul 2005 Location: MK	NAD 304 Repairs First post here. I have a NAD 304 that i use for music while i try and finnish an amp based on a gainclone design. I turned this on yesterday to find the light was staying on red, and a smell of burning comming from it. Searches have shown me that Some resistors should be changed, specificly R333 and R334 to 1 Watt. I have checked the resistors and they seem fine, but am about to change them anyway as i have some spare 1 watt resistors lying around. are there any other idea's as to what is causing this - has anyone else experianced problems like this and it not been caused by the Resistors? Thanks

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27th July 2005, 02:18 PM	#2
Matthewong diyAudio Member Join Date: Jun 2005 Location: KL	Do u have the schematic diagram, I need to refer to it first bfore I can tell you anything.

27th July 2005, 02:57 PM	#3
Leolabs diyAudio Member Join Date: Dec 2004 Location: Bukit Mertajam	Where are those resistors located???

27th July 2005, 03:24 PM	#4
Treefingers diyAudio Member Join Date: Jul 2005 Location: MK	UPDATE: have replaced resistors, it still isn't turning green. any other ideas?

27th July 2005, 04:07 PM	#6
Matthewong diyAudio Member Join Date: Jun 2005 Location: KL	I'm not able to help you since you only give me very little detail. But I can tell you that your NAD 304 protected mostly some components malfunction or spoiled. You better check that whether the transistors is still in good condition or not, then check v+ and v- voltage.

27th July 2005, 06:26 PM	#7
Treefingers diyAudio Member Join Date: Jul 2005 Location: MK	Thanks for your help so far, if there is any infomation you need please just ask - i will try to help as much as i can. I have no idea what part of the circuit is damaged, i would assume it is not the powersupply or the LED would not light up at all. But other then that i have no idea. I noticed a Fuse has slipped partly out of it's holder, as the amp worked last time it was on, could the damage be from the amp being dropped, i am guessing i should try re soldering all the joints? Leolabs: The resistors are located neer the main transistors and heatsink. There are also a second pair that seem to be part of the pre amp which are supposed to be replaced if they are not 1 Watt items, i have checked both and they are the correct values.

28th July 2005, 11:14 AM	#8
Treefingers diyAudio Member Join Date: Jul 2005 Location: MK	I have obtained and uploaded the schematic here

28th July 2005, 04:51 PM	#9
Matthewong diyAudio Member Join Date: Jun 2005 Location: KL	I think you need to check whether there is any voltage go into the pre-amp and power amp board. Because last time my friend were using NAD amp also and faced the same problem, but he finally found out that there is no supply voltage to the power amp.

28th July 2005, 08:29 PM	#10
Treefingers diyAudio Member Join Date: Jul 2005 Location: MK	Okay, the NAD 304 is capable of being bridged - would i be able to check if the pre amp is producing any power by checking this connection in relation to the phono ground?

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