AIWA CX-NH330MDK dead amp channel

Collapse
X
 
  • Time
  • Show
Clear All
new posts
  • Tom41
    Badcaps Veteran
    • Oct 2005
    • 336
    • England

    #1

    AIWA CX-NH330MDK dead amp channel

    You might have heard about this hifi in my other topic about Dolby Pro Logic - but this is an unrelated problem. It's quite old by today's standards, seeing as it only has a 3-disc CD autochanger, twin cassette decks and a built-in Minidisc drive

    Edit: Seems this unit is also known as the XR-H330MD - plenty of information for that on Google!

    The speakers on this hifi are rather unusual - there's a large bass speaker hidden away at the back inside, and smaller mid-range and high-frequency speakers at the front. The bass is driven by a separate amplifier from the mid-range and high-frequency.

    The hifi itself has four amplifiers - two for the left and right mid/high channels, and two for the bass left and right channels. The left bass channel seems to be dead; no signal at all coming out of it. Doesn't seem to come on, not even for a moment if I jiggle the connector around.

    I've had the cover off and looked at the PCB, but can't see any dry joints or blown components. There may be bad caps, but I'd have to strip the unit right down to look at the PCB. If the rest of it isn't broken, I don't want to fix it until it is

    I've also had a thought - since the bass sound is usually the same on both channels, could I connect both speakers bass channels to the working right amp output? Or would that mess up the impedance and/or blow the speakers? Or anyone got any idea how I could fix the dead channel?
    Last edited by Tom41; 04-25-2008, 05:18 PM.
    You know there's something wrong when you open your PC and it has vented Rubycons...
  • willawake
    Super Modulator
    • Nov 2003
    • 8457
    • Greece

    #2
    Re: AIWA CX-NH330MDK dead amp channel

    i think the guys would need some pics to help you.....
    capacitor lab yachtmati techmati

    Comment

    • zandrax
      Hit and miss
      • Dec 2007
      • 1157
      • Italy

      #3
      Re: AIWA CX-NH330MDK dead amp channel

      Originally posted by Tom41
      I've also had a thought - since the bass sound is usually the same on both channels, could I connect both speakers bass channels to the working right amp output? Or would that mess up the impedance and/or blow the speakers? Or anyone got any idea how I could fix the dead channel?
      Better not connect two speakers to the same output: impedence is reduced getting nearer to a short circuit (0 Ohm), the amplifier may erogate power near its limits and this means a near continuous signal instead of an alternate one. You may damage both speakers (broken coils) and amplifier (overheat and out of range operation).

      I don't know anything about component testing: my idea is swapping the right woofer with the left one, because this should help identify a driver issue from an amplifier one.

      Zandrax
      Have an happy life.

      Comment

      • Tom41
        Badcaps Veteran
        • Oct 2005
        • 336
        • England

        #4
        Re: AIWA CX-NH330MDK dead amp channel

        Both woofers are fine; I've tried connecting the left speaker to the right channel and got the bass sound out. I've also connected the right speaker to the left channel, and it's still dead - so definitely the amp or connectors.

        Connecting both woofers to the right channel did give me sound on both of them, but I didn't persevere with that arrangement since the impedance would be all wrong.

        In my opinion, the problem is occurring before the signal reaches the terminals on the back of the hifi unit - nothing to do with the speaker wires or the speaker itself.

        With the side cover off, I can see most of the PCB - nothing looks burnt or damaged, and I don't see any broken/dry solder joints. I'd like to get the PCB out and look at the front, but I don't think that's possible without stripping the entire unit down and removing all components (CD player, MD unit etc)
        You know there's something wrong when you open your PC and it has vented Rubycons...

        Comment

        • FIXITNOW
          Senior Member
          • Jun 2008
          • 128
          • UK

          #5
          Re: AIWA CX-NH330MDK dead amp channel

          does it work on headphones ?
          as sometime the headphone switch does get dirty and the connection for the speakers become open

          Comment

          • Tom41
            Badcaps Veteran
            • Oct 2005
            • 336
            • England

            #6
            Re: AIWA CX-NH330MDK dead amp channel

            Been away from the forums for a while, and yes, it did seem to be the headphone connection. I figured this out myself before I saw your post; while playing around with the unit, but thanks anyway

            The headphone socket contains a metal strip that is pushed out of the way when the headphone plug comes in. The strip then breaks other contacts inside causing the speaker amps to be shut off. Interestingly, each amp channel seemed to have its own point on the cutoff strip that it responded to - jiggling around a pencil inside the hole got the individual channels turning off!

            So all I need to do if it fails again is poke something into the headphone socket, and move it around until all the amp channels come back on.
            You know there's something wrong when you open your PC and it has vented Rubycons...

            Comment

            • Krankshaft
              Badcaps Legend
              • Jan 2007
              • 2328
              • USA

              #7
              Re: AIWA CX-NH330MDK dead amp channel

              Try spraying some Deoxit contact cleaner into the headphone jack and insert and remove a headphone plug rapidly about 10 to 15 times.

              That should clear it up if it's oxidation.

              Nobody who works on electronics should be without a good contact cleaner.

              If that doesn't work you could always solder a jumper wire across the jack switching pins or replace the jack.

              Just out of curiousity what type of headphone jack are we talking here.

              A modern 1/8" one (like the one on your computer) or an old MONSTER 1/4" one ?
              Last edited by Krankshaft; 10-14-2008, 11:45 AM.
              Elements of the past and the future combining to make something not quite as good as either.

              Comment

              • Tom41
                Badcaps Veteran
                • Oct 2005
                • 336
                • England

                #8
                Re: AIWA CX-NH330MDK dead amp channel

                It's an older 1/4'' one; I have to use an adaptor to plug any of my modern headphones (with 1/8 jacks) into it. I don't want to disable the speaker cutoff entirely, since I occasionally like to use headphones on it and wouldn't like the noise to be blasting out of the speakers as well!
                You know there's something wrong when you open your PC and it has vented Rubycons...

                Comment

                Related Topics

                Collapse

                • JunkForLess
                  1973 Magnavox. One dead channel.
                  by JunkForLess
                  I am working on repairing a 1970s Magnavox stereo console. The Left channel works perfect, but the right channel is dead at the speaker. This happens in all modes (Tape, Phono, FM Stereo). Now, I do have audio from the right channel via the "Tape Record" output, so this confirms the problem is in the right channel AF and Output amp? I also tested the speaker itself. I attached a schematic of the Right channel: AF and Output.


                  In addition to a recap, I found that R101 and R107 were both open (see arrows). I replaced R101 and R107, but they both become very hot....
                  11-01-2021, 09:46 AM
                • eccerr0r
                  old X58 triple channel board... memtest86 memory speed?
                  by eccerr0r
                  Anyone run memory speed tests with an old X58-based triple channel 1st gen or any other >2 channel board? The one I have is a Gigabyte I think.

                  Anyway I had four 4GB DDR3-1333 modules in the 6 memory slots and got around 11GB/sec memory speeds assuming that it went dual channel since it didn't have enough modules for triple channel. Now I stuck in two more 4GB modules, but they are DDR3-1600. I'm still getting 11GB/sec speeds according to memtest86...

                  Just wondering, anyone do memory speed analysis on these triple (and higher) channel memory boards? Are there any...
                  06-28-2025, 09:06 AM
                • spleenharvester
                  Reverse engineering of 18650 4-channel tester
                  by spleenharvester
                  Hi friends

                  I have reverse engineered this tester, schematic is attached and is complete except for capacitor values. These testers annoyingly have no model number but they are the ones you find on the first page of just about any website if you type in "18650 4-channel tester". There is also a 2-channel variant and a newer 8-channel variant. They are very cheap (about £15) and can measure voltage, current, internal resistance and capacity. They have a multicolour display for all these statistics. They also have terminal blocks so that if you want to use a breakout board...
                  05-04-2025, 02:43 AM
                • dicky96
                  American Audio VLP1500 Distorting on one channel
                  by dicky96
                  Hi guys I have a VLP1500 amplifier here - one channels works fine and the other channel distorts even at low volume settings

                  Protection and Clip LED are off

                  There is something wrong with the BIAS voltages around T16 and T18 (in particular) on the bad channel

                  I tested all diodes and transistors in this area in circuit with diode mode - both channels seem identical. Same in resistance mode across all the resistors here.

                  The output DC voltages on pin1 and pin8 of the 5532D dual op amp at the input of each amplifier module are the same, and the audio...
                  07-13-2022, 05:25 AM
                • dicky96
                  Hitachi V19B01922 Channel Tune problem
                  by dicky96
                  Hi Guys
                  I have a customer who has two Hitachi TVs in his bar, one is the model in the thread title and the other is a larger screen but has the same setup menu

                  He also has an LG TV, so three screens in the bar

                  I installed three Satlink ST-6503 DVB-T Modulators
                  This model https://www.aliexpress.com/item/32916553905.html

                  These connect to three satellite receivers via HDMI cables and then connect to a 4 way RF Amp that connects to the TVs on aerial cable. There is no incoming terrestrial antenna. I set the channel ID on the modulators to...
                  02-09-2023, 09:20 AM
                • Loading...
                • No more items.
                Working...