Replacement cap recommendation for sub amp?

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  • JimBanville
    Senior Member
    • Aug 2020
    • 118
    • United States
    #1

    Replacement cap recommendation for sub amp?

    I picked up a KLH SP-90 subwoofer amp it looks suspiciously like the NHT MA-1 amp. There's a board in the KLH that actually has "MA-1" printed on it. Anyway, it powers on and I can hear/feel a slight "noise" from a subwoofer cone attached to the amp, but I get no audio. The two main caps (6800uf 50v 105 degree, 25mm/45mm) are bulged and I measured "OL" on my meter. The leads fell off as I removed them. Can someone recommend a cap that's in-stock somewhere that would be a good replacement? And would these being "bad" cause absolutely no audio? Thanks!
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    • redwire
      Badcaps Legend
      • Dec 2010
      • 3906
      • Canada
      #2
      Re: Replacement cap recommendation for sub amp?

      You can look at Mouser or Digi-Key for a 6,800uF 50V snap-in the same size.
      As mains filter capacitors, they should not cause no audio. Their leaking may have damaged traces, fuses blown, damaged power amp section etc. so I would look for further trouble.

        Comment

        • JimBanville
          Senior Member
          • Aug 2020
          • 118
          • United States
          #3
          Re: Replacement cap recommendation for sub amp?

          Originally posted by redwire
          You can look at Mouser or Digi-Key for a 6,800uF 50V snap-in the same size.
          As mains filter capacitors, they should not cause no audio. Their leaking may have damaged traces, fuses blown, damaged power amp section etc. so I would look for further trouble.
          Rats! That's bad news. The new caps would be at least $15 delivered. All the other components look fine visually. It's really not worth the potential cost beyond those caps. Thanks for relying

            Comment

            • JimBanville
              Senior Member
              • Aug 2020
              • 118
              • United States
              #4
              Re: Replacement cap recommendation for sub amp?

              Originally posted by redwire
              You can look at Mouser or Digi-Key for a 6,800uF 50V snap-in the same size.
              As mains filter capacitors, they should not cause no audio. Their leaking may have damaged traces, fuses blown, damaged power amp section etc. so I would look for further trouble.
              Ok...either it was those caps that weren't allowing the amp to make sound or it's just a coincidence, but I replaced the caps and it works!
              I found a couple old onkyo receivers in a pile of electronics and other junk on the side of the road where someone was cleaning out an old house. One (looks to be from the late 80's - early 90's) had two Nichicon 6800uf 50V caps in it. I pulled them and they STILL measured very well on my component tester. Capacity as great as was ESR. Popped them in and the amp worked again! It acted differently as well. Before, when you powered it on, both the standby and power lights illuminated and stayed lit. When you turned it off, they both went out. Now, when you turn it on, the power and standby lights illuminate, but the standby quickly goes out. And when you turn it off, they both illuminate and fade out over time.

              Now, I'm curious if this is a NHT subwoofer amp (MA-1?) clone or they were just made by the same factory. The high level speaker input board has MA-1 written on it and the chassis' look very similar.
              Attached Files

                Comment

                • JimBanville
                  Senior Member
                  • Aug 2020
                  • 118
                  • United States
                  #5
                  Re: Replacement cap recommendation for sub amp?

                  Originally posted by JimBanville
                  Ok...either it was those caps that weren't allowing the amp to make sound or it's just a coincidence, but I replaced the caps and it works!
                  I found a couple old onkyo receivers in a pile of electronics and other junk on the side of the road where someone was cleaning out an old house. One (looks to be from the late 80's - early 90's) had two Nichicon 6800uf 50V caps in it. I pulled them and they STILL measured very well on my component tester. Capacity as great as was ESR. Popped them in and the amp worked again! It acted differently as well. Before, when you powered it on, both the standby and power lights illuminated and stayed lit. When you turned it off, they both went out. Now, when you turn it on, the power and standby lights illuminate, but the standby quickly goes out. And when you turn it off, they both illuminate and fade out over time.

                  Now, I'm curious if this is a NHT subwoofer amp (MA-1?) clone or they were just made by the same factory. The high level speaker input board has MA-1 written on it and the chassis' look very similar.
                  Ok...found this pic of an opened MA-1 and the boards are rearranged, but it looks just like the parts in this KLH amp...
                  Attached Files

                    Comment

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