another NAD 304 whit the red light on... (2024)

jaycee

Member

Joined 2004

2010-05-06 9:46 pm

#3

    • 2010-05-06 9:46 pm
    • #3

    Hifi Engine has a pretty good copy of the service manual. Sign up is free.
    NAD 304 | Owners Manual, Service Manual, Schematics, Free Download | HiFi Engine

    The tricky thing with this amp is that it is a class H amp with two power supplies that are switched according to the output signal.

    Even if he knows no English, if he is good with electronics he should be able to read the schematics. The language of electronics is fairly universal another NAD 304 whit the red light on... (2) This does however look like a complex amp to service, and I would really recommend someone with some experience.

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    east electronics

    Member

    Joined 2006

    2010-05-06 10:24 pm

    #4

      • 2010-05-06 10:24 pm
      • #4

      jaycee said:

      Hifi Engine has a pretty good copy of the service manual. Sign up is free.
      NAD 304 | Owners Manual, Service Manual, Schematics, Free Download | HiFi Engine

      The tricky thing with this amp is that it is a class H amp with two power supplies that are switched according to the output signal.

      Even if he knows no English, if he is good with electronics he should be able to read the schematics. The language of electronics is fairly universal another NAD 304 whit the red light on... (4) This does however look like a complex amp to service, and I would really recommend someone with some experience.

      just took a look at the schematic after reading your post regarding class H ....god jay cee you are right .... i wonder what NAd people had in mind ..... Mad probabaly not nad ha ha ha ha ha

      jaycee

      Member

      Joined 2004

      2010-05-06 11:21 pm

      #5

        • 2010-05-06 11:21 pm
        • #5

        Yeah it seems odd to me. It seems to be an effort to allow high power peaks but keep the heatsink/case in proportion for a 30W amp. Seems over-complex to me.

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        al37perez

        Member

        Joined 2010

        2010-05-08 3:24 pm

        #6

          • 2010-05-08 3:24 pm
          • #6

          more data about the failure...

          Well, I have made something. First, thans i have the schematics.
          The light is still always in red. But I have used the headpones jack.
          When I used the balance, is clearly a poor sound in the right channel, fading off when I move the balance to the right. Left channel appears to sound well.
          Is this a clue for resolving the failure?
          Has anybody knows where are resistors 333 and 334?
          Thank you very much.

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          Y

          yachadm

          Member

          Joined 2009

          2014-03-06 5:24 am

          #7

            • 2014-03-06 5:24 am
            • #7

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            R

            rob100961

            Member

            Joined 2012

            2021-03-07 2:46 pm

            #8

              • 2021-03-07 2:46 pm
              • #8

              Hi,

              I inherited a NAD 304 with the same problem mentioned above, except mine would power up for a second or so (green light on) and play music, but then you'd hear a click and the red light would come on (the yellow light being on or not, just depends on the position of the "soft clipping" switch on the rear of the amplifier, so ignore it for this fault). Powering off then on repeats the same scenario.

              I've read through a number of posts on here about this issue, and thought I'd try replacing R333, and R334 with a pair of 47K, 1 Watt, metal film resistors, as suggested in posts. You can easily get to these by unscrewing the panel on the bottom to get to the solder joints - no need to take it all apart. I'm happy to say this has cured my issue, and I haven't had to do anything else. I've had it on for several hours, so am happy that it's going to be a good repair. The original resistors looked fine, but when I measured them after removal they both seem to be open circuit.
              Now when you turn it on you get the red light for a couple of seconds, then a click and the green light comes on and it all works fine. When you switch off the red light comes on for a few seconds (as the power supply capacitors drain I'd imagine), this seems correct to me.
              I've attached a few pictures so anyone else attempting this repair can find R333, and R334 easily. They're the large (1 Watt) pink resistors.
              Hope this helps others, and thanks to all for the great resource this site is.

              Rob

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              JohnJayaratnam

              Member

              Joined 2021

              2021-09-02 10:31 am

              #9

                • 2021-09-02 10:31 am
                • #9

                I have a NAD 304 with the red light on. I tried changing the R333 and 334 and its the same. Now, R360 is getting red hot. Any experience? Please Help

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                JohnJayaratnam

                Member

                Joined 2021

                2021-09-02 10:32 am

                #10

                  • 2021-09-02 10:32 am
                  • #10

                  will adjusting the idle current effect the r360 to light up?

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                  another NAD 304 whit the red light on... (2024)

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