Onkyo M-504 help needed.

Bought this a couple of months ago. Meters lit up when I bought it. Just hooked it up to my two channel set up. No sound. Opened up. Super clean unit. No fuse in one fuse holder? I wonder why no fuse in there? Such kool meters! Thanks for any help. Peace. Dxo9ns9cf13gb.jpeg
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MIT Magnum MH-750, Monster HTS 5100MKII, Mitsubishi rear projection 73, PS4, Def Tech 15” sub,LSIM 706c, Sunfire Signature Grand 425 x 4,Parasound hca 120, LSiM 702 x 4, Oppo 103D, SDA SRS 1.2, Pioneer Elite SC63 , Pioneer Elite BDP-05



“Why did you get married if you wanted big speakers?”

Comments

  • F1nut
    F1nut Posts: 47,063
    Put a fuse in it.
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  • Dabutcher
    Dabutcher Posts: 2,409
    Thanks ,my brother. Next step I was going to make. Wish me luck. Peace. D
    MIT Magnum MH-750, Monster HTS 5100MKII, Mitsubishi rear projection 73, PS4, Def Tech 15” sub,LSIM 706c, Sunfire Signature Grand 425 x 4,Parasound hca 120, LSiM 702 x 4, Oppo 103D, SDA SRS 1.2, Pioneer Elite SC63 , Pioneer Elite BDP-05



    “Why did you get married if you wanted big speakers?”
  • ken brydson
    ken brydson Posts: 8,268
    Dabutcher wrote: »
    Thanks ,my brother. Next step I was going to make. Wish me luck. Peace. D

    Have someone hold your beer and stand back a ways...
  • Dabutcher
    Dabutcher Posts: 2,409
    Fuse blew as soon as I turned it on.
    MIT Magnum MH-750, Monster HTS 5100MKII, Mitsubishi rear projection 73, PS4, Def Tech 15” sub,LSIM 706c, Sunfire Signature Grand 425 x 4,Parasound hca 120, LSiM 702 x 4, Oppo 103D, SDA SRS 1.2, Pioneer Elite SC63 , Pioneer Elite BDP-05



    “Why did you get married if you wanted big speakers?”
  • erniejade
    erniejade Posts: 5,880
    I used to have one. Depending on $ to fix it, I thought they were a good sounding amp. I ran mine for years and sold it when I got a Sunfire.
    T+A PA 1530R,Wireworld Silver Eclipse 8 SC, Tyler Highland H2, Audioquest Thunderbird Interconnect , Innuos Zen MK3 W4S recovery, WireWorld Platinum Starlight 7 USB, Border Patrol SE-I

    Have but haven't used in a while: Cayin SCD50T, Technics 1200, Denon DL160, Jolida D9
  • tonyp063
    tonyp063 Posts: 938
    hifiengine has the service manual with wiring diagram.
    https://www.hifiengine.com/manual_library/onkyo/m-504.shtml

    According to it, that fuse is on the 120V side before the power transformer. Typically (and not always) a short in the power switch would cause what you are seeing.
    At least, that's where I would look first
  • Dabutcher
    Dabutcher Posts: 2,409
    I have a second one with one side that has gone out. Just been sitting for years now. I could use it for parts. When you say power switch, do you mean the button I push to power on? As always thanks for all your help. D
    MIT Magnum MH-750, Monster HTS 5100MKII, Mitsubishi rear projection 73, PS4, Def Tech 15” sub,LSIM 706c, Sunfire Signature Grand 425 x 4,Parasound hca 120, LSiM 702 x 4, Oppo 103D, SDA SRS 1.2, Pioneer Elite SC63 , Pioneer Elite BDP-05



    “Why did you get married if you wanted big speakers?”
  • tonyp063
    tonyp063 Posts: 938
    Yes.
    You'll also want to check the power transformers for continuity & shorts.
    The aforementioned manual has a good schematic & so troubleshooting tests.
  • DaveHo
    DaveHo Posts: 3,234
    He shows a pic with the meters lit up. Wouldn't that rule out the transformer & power switch?
  • tonyp063
    tonyp063 Posts: 938
    If I'm reading the schematic right (and there's no guarantee of that because I have old eyes) no.
    It looks like each PS transformer is fused separately on different switch legs. The meters get their light power from only one of the transformers, so the other leg of the circuit is the suspect one.
    See the bottom of page 9

    Also look at the precaution on page 3 to do an insulation test measurement.
    unplugged. both fuses in.
    then run a meter between each plug leg & chassis ground with the switch on.
    Should see over 10M ohms
  • daddyjt
    daddyjt Posts: 1,607
    What's your electronics knowledge? Do you own a DMM? If so, locate the output transistors and check for leg-to-leg and leg-to-ground shorts.
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  • Not sure if you’ve fixed your problem but you probably have a shorted or grounded transistor in your left channel.