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Home audio amplifier failure

Discussion in 'Electronic Repair' started by Gary, Jul 16, 2005.

  1. Gary

    Gary Guest

    First, this is my first entry into this group. I ran a NG search for this
    problem, and the result(s) indicated
    here. Sorry, if that was wrong.

    I have an Onkyo home audio component system. The
    amplifier in this system(Onkyo A-RV401) has flamed
    out, as least I'm pretty sure it's the amplifier.

    Next, I'm not an electronics guy. I'm just looking for a
    little seasoned advice.

    The system no longer produces any sound, no tuner,
    tape, CD, headphones, nothing. However, I can crank
    up the volume to full, and faintly hear the audio. As
    usual, this worked fine one day, and failed the next.

    It appears that this component can be replaced with
    something like, for around $400-600. It also appears
    that current models have the tuner/amplifier integrated
    into a single unit, where the existing unit(s) are separate.

    It's my opinion(only opinion) that replacement should
    be the choice, rather than a repair attempt.

    Comments?

    Thanks, for the help.

    Gary
     
  2. CJT

    CJT Guest

    Used amps in good condition can often be found at a small fraction of
    the price of new.

    Remember - you were happy with your (used -- by you) amp until it broke,
    so why not consider a good used (by somebody else) amp? There are lots
    of people who regularly "trade up" whether they can hear the difference
    or not -- it's a form of self-flattery. That puts some pretty good
    equipment on the market cheap.
     
  3. TimPerry

    TimPerry Guest

    find a repair shop and have it fixed... should cost $75 to $100 for repair
     
  4. NSM

    NSM Guest

    Perfectly serviceable but it's your choice. I even see them in thrifts, the
    only problem being testing them there.

    N
     
  5. Gary Walker

    Gary Walker Guest

    Yes, you are quite right. And, I often criticize those for
    making a brand switch under the light of comparison
    of a bright shiny new model vs. retention of the current
    brand.

    Although I wasn't really looking specifically to change
    brands, I was looking at everything available. Things
    like this change/evolve so quickly, it's easy for me to
    get behind.

    Regarding the used/trade-in issue, I hadn't really given
    that any thought. It is a good suggestion. But, for some-
    one like me, with minimal ability to detect potential
    problems in electronic equipment, I'd prefer new.

    Also, unless possibly a high end audio outlet, I've have
    no idea where to find used equipment as this. I guess
    the pawnshop is certainly an option, but I'd think one
    would need considerable more savvy than me.

    Thanks,

    Gary




     
  6. Gary Walker

    Gary Walker Guest

    That's my take on the whole thing. But, I will take this,
    and the other suggestions into consideration. Problem
    is, I don't know an RF from a DSP, and unless I find
    someone I can trust, my scrutiny is suspect.

    Thanks,

    Gary
     
  7. Gary Walker

    Gary Walker Guest

    I will check into it. I do have a friend who repairs guitar
    amplifiers. Not that I would try to cop a free repair, just
    that I would trust him. But, I thought that one could
    easily exceed the unit value by attempting repair.

    Thanks,

    Gary
     
  8. up the volume to full, and faintly hear the audio>


    Sounds like maybe the tape monitor is engaged. Maybe nothing wrong worth the
    amp. Even if the amp does have a problem, the A-RV401 is a nice model, worth
    repair.

    Mark Z.
     
  9. Gary Walker

    Gary Walker Guest


    I understand your comment, but although I have engaged
    all the input sources at one time or another, the faint audio
    can be detected as from the source intended.

    Yes. it has been a great unit. It was suggested earlier that
    repair might be worth looking into, which I will. I'd hate
    to just throw the whole thing away due to something small.

    Thanks,

    Gary
     
  10. Then perhaps a failure of the regulated power supply area. You'd hear
    nothing at all if the main amp was blown or if there were a large DC offset.
    Could be one or more open resistors feeding voltage regulator(s) in the
    power supply. Fairly common problem on similar model Onkyo receivers, though
    I've only worked on one or two amps like yours, and it's been a while.

    Mark Z.

    Mark Z.
     
  11. Gary Walker

    Gary Walker Guest


    Well, as I said, I don't really know. I can say that this amp
    never runs about 30% volume, I just use it mostly for
    headphone listening. If I juice up the volume to 100%, I'll
    hear the audio at about the depth I might expect at 1-5%.

    "The amplifier's just ain't amplifying". <g>

    I still haven't decided, intending on contact of an amp
    repair friend. But, I have found another equivalent
    replacement Onkyo for ~$300 at Fry's. It's a TX-8511.

    Thanks,

    Gary
     
  12. Ron(UK)

    Ron(UK) Guest

    Just a thought, but it hasn`t got those linking plugs or jumpers
    between the preamp and power amps has it? have they been removed, or has
    some other piece of kit been disconnected?

    Ron
     
  13. Gary Walker

    Gary Walker Guest


    Unfortunately, I don't fully understand "linking plugs",
    and never really have fully understood "preamp" vs.
    "power amp". But, I can say this:

    The system(components:tuner, amplifier, headphones)
    were in use the previous evening ~22:30-23:30, with-
    out sign of failure. This system has been used daily for
    Proceeding to use the system during the subsequent
    day and, no audio.... I guess something could have
    wiggled loose, but since I can get this faint audio, and
    I have done a cursory "reset" of all rear panel attach-
    ments, I just assume it's gone.

    Although this system is only used for 1-2 hour periods
    at a time, it will sometimes remain on for 24 hour periods.

    Although not electronically oriented myself, I have to
    assume these things have a MTBF. I guess after >10
    years of flawless service, my number's up. Additionally,
    the components are positioned in a very dusty area, and
    haven't been cleaned since new. Actually, it's no more
    dusty that any other room, but due to lack of cleaning,
    it appears very dusty.

    IOW. The whole thing is located in a music room, with
    other instruments and junk(need I say more?).

    Thanks,

    Gary
     
  14. Jim Adney

    Jim Adney Guest

    Separate units like yours are generally easier to fix than integrated
    units, so this helps. I don't know anything about your model, but my
    first inclination would be to see if it can be fixed. These items
    generally are fixable and for much less money than the replacement
    cost you mention.

    The fact that both channels both seem to have died at the same time
    makes this seem like it might be a simple problem. It might pay to get
    your friend over there just to check out the system and the switch
    settings (like the tape monitor that Mark mentioned.)

    I agree completely with your other posts that it would all depend on
    finding someone you think you can trust to take a look at it.

    -
     
  15. Gary Walker

    Gary Walker Guest

    Thanks. I am weaning off the unit for these last few days.

    That'll make my diagnosis more thorough.

    Gary
     
  16. CJT

    CJT Guest

    That's a good point. It suggests some problem with a section that's
    common to both channels -- like a power supply.

    It might pay to get
     
  17. NSM

    NSM Guest

    On the back there may be some connectors labelled Out and In which need to
    be connected together to make the system work. Can you post a picture of the
    back somewhere (not in this group please)?

    N
     
  18. Gary Walker

    Gary Walker Guest

    Well yeah, I'm aware of the component plugs on the rear.
    I'd just never heard them referred to as linking plugs.

    Come to think of it, I'd never really known their true
    description other than RCAplug/Miniplug etc.

    With regard to a picture of the rear, no I don't have one,
    and I have no scanner with which to record the diagram
    in the hardcopy I do have.

    However, I've managed to locate:
    http://onkyousa.com/own_manuals.cfm?cat=Receiver
    which shows the A-RV401 instruction manual. Although
    it doesn't seem an exact copy of the hardcopy I have, it
    does have some documentation. But, unlike my hardcopy,
    I didn't see a simple back panel schematic as is shown in
    my hardcopy. Perhaps, I just overlooked it.

    The diagnostic section occurs on pp.15.

    But....

    I did overlook/fail to think about/stupidly ignore the diag-
    nostic section(aka troubleshooting) in either copy. Using
    the hardcopy manual, and following the procedures for
    "power but no sound", I see:

    Tape monitor on - No, but I do now recall having prob-
    lems with this in the past when I'd press the wrong butt-
    on in the dark. Pressing tape2 switches to tape2 input,
    but merely pressing tuner will not return to tuner, but
    shows T2 monitor. Another press of tape2 releases the
    T2 monitor, and returns the faint signal.

    Bad connections - Possible, but since I've reset all conn-
    ections, and I can get the faint audio from all sources(
    tuner, CD) available, this possibility seems very unlikely.

    Amplifier protection circuitry has been activated - I have
    no clue. The response here is to contact the service cen-
    ter.

    In the online troubleshooting guide, a muting button is
    described. My unit has no mute button, or I just can't
    seem to find it. It does have a standby button, and that
    will disable sound, but it is correctly positioned. Perhaps
    this standby is synonymous with muting?

    Although the online manual indicates that "protect" will
    be shown if the protective circuitry activation has occ-
    urred, my hardcopy manual make no mention of this. I
    assume I have no protect designation.

    I did just returned from a closer unit inspection. In the amp view window,
    where the input source is shown, I do see a "very" small muting word. Review
    of the online manual pp. 11 describes muting as activated via the remote
    unit. Well, although I have had the remote connected(I guess it's a remote
    receiver, because the remote is wireless), not only have I never used the
    remote, I'm not really sure even where it is. The text suggests that the
    only way to de-mute is via the remote, or a cycle of the amp's power. I can
    certainly say that a power cycle on the amp has no effect on this.

    Further research on this seems to indicate that the muting
    function is stuck on. Even after disconnecting the rc cable
    from the amp(one rc cable connects the tuner to the amp,
    and the other rc cable connects the tape to the CD), the
    amp continues to initialize in mute mode. It appears that
    this is probably the problem, but I'll be damned if I know
    how to correct it. Perhaps, I'll either have it looked at,
    or contact Onkyo for assistance(unlikely they'll bother
    with equipment this old).

    Sorry, for the verbosity....

    Thanks,

    Gary
     
  19. NSM

    NSM Guest

    That'll do it. Until you can un mute it you will have no sound.

    As for the linking or jumping plugs, this model probably doesn't have them
    but if you look at the bottom right diagram on page 4 of the A-RV401 manual
    on a model that _WAS_ designed this way the equalizer jacks would be
    permanently connected in to out, left to left and right to right with very
    short cables. Removing these without connecting an equalizer would also cut
    the sound.

    N
     
  20. Gary Walker

    Gary Walker Guest

    Thanks, I did find the remote, and will research possibly
    trying to use it to de-mute, but I don't hold much hope.

    I've also sent mail to Onkyo explaining the situation, but
    don't hold much hope there either.

    I'll post my progress as this saga unfolds.

    Thank you, and everyone for the assistance and contri-
    bution(s).

    BTW. That "muting" word is very very tiny, meant for
    eyes much younger than mine.

    Gary
     
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