Pioneer QX-949A Power Switch Needed

Discussion in 'Pioneer Audio' started by Davron94, Feb 11, 2016.

  1. Davron94

    Davron94 Active Member

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    Hey All, I have searched high and low on the internet to find a ASG-070 Power Switch for my receiver. I've checked all the Pioneer parts sites that I could find and no one seems to have it. Anybody have one that they can salvage, OR, can this switch be fixed, disassembled and reworked, etc.? Or could it be the flat ceramic caps on top, butI would think not. I gave it a couple good shots of DeOxit and worked it about 50 times. It worked good for a while to power up the unit, but now its hit and miss. If I work it a few times and run the mode selector and function switches back and forth a few times, (with the unit unplugged), for whatever reason it will power up when plugged back in. But then after it sits powered down, it will not power up again.
     
  2. larryderouin

    larryderouin Do I get Food, Med's, or more gear this Month? Subscriber

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    The QX-949 lists 2 different switches for the power switch. ASG-070 (4 prong O/S use) and the ASG-043 (2 prong U.S. use)

    I'm presuming that the QX-949A that you have is a non US version (multi-voltage)as the US version shows the ASG-043-0 as the power switch.

    The ASG-070 is used in the (Multi-voltage switch)
    QX-747
    QX949A


    The "ASG-043-0". is also used in the following gear; (U.S. single voltage switch)
    QX-747
    QX949 &949A
    SA-9500
    SA-9900
    SX-535
    SX-636

    Physically they are probably interchangeable. Electrically they are not. So make sure you get the correct one.
    On the back of your unit should be a sticker with a 3 letter designation like FUW on it. You need that designation when you ask about the donor unit.

    Couple of things to do.
    1.) on POWER SWITCHES, use ONLY a NON Residue Contact cleaner, like CRC QD Contact cleaner. All it's going to do is remove the loose carbon and sludge from the inside, leaving clean "BURNT" contacts. DeOxit has lubricants that gum up the inside of power switches of this type especially if it's been arcing . You still either have to tear it down and burnish the contacts or replace the switch, usually from another unit. There are NO NEW SWITCHES to be had. With this being a push- push switch it's possible the latch is broken inside and it's not latching in the on position.(This is the more probable scenario).

    2.) Find a parts donor unit from the above list(s) and use it's (correct) switch.

    3.) Contact AK sponsor "YESTERDAYS AUDIO". They deal strictly in 70's era PIONEER PARTS. Email with the part number to see if they have it if it's not in the parts catalog online. (ON AK HOME PAGE is a SPONSOR LIST, click on y'days audio, and you'll be sent there).
     
  3. Davron94

    Davron94 Active Member

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    Thanks for the info Larry! I am sure its a ASG-070. I had contacted "YESTERDAYS AUDIO", along with several other Pioneer parts places, but none of them have any switches.

    The switch does engage properly. I might have given it too much DeOxit, and have gummed up the inside. I'll try some of the CRC and see if that helps.
    This one was recommended to me:

    http://www.ebay.com/itm/172071874946?_trksid=p2060353.m1438.l2649&ssPageName=STRK:MEBIDX:IT

    but I'm not sure if its a DPDT, which is supposedly what I need.

    Thanks,
     
  4. larryderouin

    larryderouin Do I get Food, Med's, or more gear this Month? Subscriber

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    Break out your meter and do some continuity testing from the plug thru the switch (unit unplugged and no power). Just for S&G open the fuse holder and clean the fuse and the holder contacts.
     
  5. Davron94

    Davron94 Active Member

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    Are you talking about the main fuses or is there a fuse in the power switch? I've already given the unit a good cleaning, including all of the 4 internal fuses and external main fuse, including all contacts.
     
  6. jblmar

    jblmar JBL & marantz

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    Another suggestion.
    Connect your DMM to the ac plug.
    Set your DMM to Continuity.
    Depress the power switch.
    If the switch is good, your meter will 'Beep.'
    If you don't have the Continuity setting on your DMM, the Ohms function will work just as well. Only there will be no Beep.

    I can suggest a very good replacement switch for you, but I'm not sure the mounting screws or the silver button from your amp will fit. If possible, can you take a few pics of the switch and measure the space of the mounting bracket?
     
  7. QSilver

    QSilver Super Member

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    1,094
    If you have any switch left that you can clean up to make a good contact, one member here has come up with a method of using a Triac to switch the amp on and off - while using the switch as the trigger for the Triac.

    That way, it doesn't have to cope with switching high current and inrush and will last forever once you put the Triac in. I've just done this on my QX-8000 and it works perfectly and now I don' have to try and source an unobtainium switch! :thumbsup:
     
    audiojones likes this.
  8. audiojones

    audiojones Jonesin' for audio Subscriber

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    ⬆️ Did the same thing with my QX-949A once I found another power switch for it. That sucker was hard to find and I'm sure not going through that again! I've done k7sparky's triac mod on a bunch of other receivers with weak power switches too and it works like a charm!
     
  9. tsd71

    tsd71 RIP Tom Petty Subscriber

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    I have a bunch of power switches OEM, push button style, what are the specs of you switch,dimensions,etc.
     
  10. tsd71

    tsd71 RIP Tom Petty Subscriber

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  11. QSilver

    QSilver Super Member

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    Luckily mine was salvageable was only just beginning to burn. After cleaning up the contacts, it was good enough for the switch. Though, I noticed my switch was rated for 120V 6A which is the rating of the primary fuse. In rush will be way over this I imagine so it's no wonder so many of these switches burn up over the years...
     
  12. audiojones

    audiojones Jonesin' for audio Subscriber

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    Mine was missing altogether when I got the receiver, otherwise I would've done the same. One thing's for sure, there is absolutely no room inside the QX-949 for a power relay. That's why the Littlefuse thyristor is such a perfect solution, you can always find a place for it somewhere - even in the jammed up mess inside the QX-949!
     
  13. Davron94

    Davron94 Active Member

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    Its a 120V 6A unit. I don't see any other specs in the manual for the power switch. I can't find the dimensions for the switch anywhere, but the part number is the ASG-070.
     
  14. Davron94

    Davron94 Active Member

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    Let me get it broken down and I'll take a few pics.
     
  15. Davron94

    Davron94 Active Member

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    Are there any instructions around for doing this mod? what's the "traic"?
     
  16. audiojones

    audiojones Jonesin' for audio Subscriber

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    Look at k7sparky's thread here, all instructions and diagrams are within it: http://www.audiokarma.org/forums/index.php?posts/6552885/

    If you can clean up your existing switch to the point where it works marginally then the Triac mod will most likely work for you. It takes the load off of the switch contacts, basically it's a solid state relay.
     
  17. jblmar

    jblmar JBL & marantz

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  18. jblmar

    jblmar JBL & marantz

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    The 227 switch listed above has a contact rating of 7A.
     
  19. Davron94

    Davron94 Active Member

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    Nice! Thanks for the link! I think I'll give this a go, once I get the power switch out and see what kind of condition its in. I think I may just have junked it up a bit too much with the DeOxit. This mod looks fairly simple though for someone like me that just dabbles in electronics repair work. I'll just need to read the instructions a couple hundred times to understand the connections!
     
  20. Davron94

    Davron94 Active Member

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    Would you happen to have any information you can give me on which wires to jumper to the traic on the QX-949A? I'm not following the instruction very well in K7sparky's link, since its kind of generic. Any help is greatly appreciated!

    Thanks,
     

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