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Yamaha CR (relay problem?)

Discussion in 'Yamaha' started by tightplatoni, Oct 29, 2012.

  1. petehall347

    petehall347 the brandy coffee man Subscriber

    Messages:
    27,886
    Location:
    uk.. the middle bit
    adding some flux would have helped . saying that as long as there was enough flux left on the original solder it will be fine .
     

     

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  2. avionic

    avionic " Black Knights " Subscriber

    Messages:
    43,796
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    Fort Dodge, Iowa
    Adding a bit of new solder and flux makes the solder flow much easier and leaves a nice shiny ,smooth connection.:thmbsp:
     
    Last edited: Nov 1, 2012
  3. tightplatoni

    tightplatoni New Member

    Messages:
    11
    thanks guys, everything seems fine so far and it's been a few days..but just for future reference, how do I know what kind of solder/flux to use if I need to?
     
  4. avionic

    avionic " Black Knights " Subscriber

    Messages:
    43,796
    Location:
    Fort Dodge, Iowa
    Last edited: Nov 3, 2012
  5. clearsoft

    clearsoft New Member

    Messages:
    9
    I had a similar issue with my CR-1020. Over the years, I have repaired quite a few Yamaha CR receivers and this one was particularly difficult. Many many hours of troubleshooting, so wanted to share here in the hopes of saving others some heartburn.

    After a full power supply recap (both pcbs) and power transistor upgrade to higher voltage TIP31C in the supply, the protection relay would not fire. The -25V output sat at -10V. Cleaned the flux and grime off the bottom side the PCB and the output went to +6V. Disconnected the two purple wires from the -25V post to eliminate loading. No improvement. Removed and retested all 4 transistors; junctions not shorted nor open.

    Decided to look at the .01uF capacitors. In circuit across the terminals, the one on the -25V supply measured 6 kOhms whereas the one in the +25V supply measured 3 megohms. Pulled the caps; neither was leaky. Pulled the 4 transistors again. Still 6 KOhms...strange.

    Used flux remover to clean the top side of the power supply PCB around the .01uF cap locations, removing glue residue near the heatsinks. Resistance now 2 megohms. Apparently the glue that Yamaha used was not totally electrically benign and the -25V supply is extra sensitive to leakage current (check out the circuit topology).

    Reinstalled all components. Reconnected all wires. Voltages perfect. Relay works.
    —Ed
     

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