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yamaha RX-V365 Receiver

Discussion in 'Electronic Repair' started by WLD_Bill, Mar 24, 2013.

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  1. WLD_Bill

    WLD_Bill Guest

    Pressed power button, unit powers off after 3 seconds.

    Bypassed protection mode by holding "Effect" & "Night" buttons while
    pressing power button.
    Unit displayed the code "PRD PRT 210"

    Manual states as follows....

    When there is a history of protection function due to abnormal DC
    output

    PRD PRT:xxx (xxx AD value when the protection function is working)

    Cause: DC output of the power amplifier is abnormal.

    Supplementary information:
    The protection function worked due to a DC voltage appearing at the
    speaker terminal.
    A cause could be a defect in the amplifier.
    If the power is turned on with the abnormality unsolved, the
    protection function works in about 3 seconds to turn
    off the power.

    Ideas where to start? LOL.... DC voltage appearing at the speaker
    terminal? None showed
    up with a DVM
     
  2. David Farber

    David Farber Guest


    Maybe something got lost in the translation. DC output of the power
    amplifier will only show up at the speaker terminals if the speaker relay is
    energized. It's not clear to me what protection functons are being bypassed
    by pressing the "Effect" & "Night" buttons. In other words, check the DC at
    the power amp output before it goes to the protection relay. Other than
    that, perhaps our resident Yamaha expert, Mark Z. will chime in with some
    advice. (-:
     

  3. The translation is a bit off. It's trying to say that there WAS a DC offset
    at one or more speaker terminals, therefore the protect was activated.
    The DC is actually detected BEFORE the speaker relays via sensing resistors
    going over to the appropriate DC PRT input on the microprocessor.
    The value 210 translates as follows:

    divide 3.3 by 255. This equals 0.01294117

    Multiply this value times the error code 210. The result (2.717647) is the
    voltage seen at that input on the microprocessor. Actually it's quite
    accurate - no need for a multimeter here.

    The acceptable range (maybe 70 to 125 etc) multiplied the same constant
    would give the "normal" DC range that should be seen by the microprocessor.

    Bottom line - probably one channel has a DC offset caused by a bad output
    IC.

    That DC voltage can be measured at any of the white emitter resistors
    sitting in front of the output IC's. One white dual resistor for each
    channel.

    In this case, since it is not an over-current shutdown, the protection
    cancel method shown in the manual can force the receiver to stay ON so that
    voltage readings can be made.

    Enough?

    Mark Z.
     
  4. WLD_Bill

    WLD_Bill Guest

    Thank you so much guys. Will post my findings soon.
    PS: I've been toggling the power on and off to get readings. Protection bypass
    didn't seem to matter, although unit will stay running in firmware update mode.

    Regards:
    Bill
     
  5. WLD_Bill

    WLD_Bill Guest

    Measured the center post on ceramic resistors in front of amp i.c.'s
    (4) measured .8vdc
    (1) measured 52.6 vdc. (front-left speaker output) of STK433-330-E
    Replace the I.C. ? Any other offending parts I should look at?

    I heard a high pitch sound the other day and thought it was around the voltage regulators on operation board 2. LOL (not even close) It was the STK433-330 I.C. . Oh well, the regulators got a new grease job and the 6.3v 1ufcaps checked out good with ESR and LC meters.
     
  6. WLD_Bill

    WLD_Bill Guest

    Checked Q119 (2n5551c) with dvm. I checked ok.
     
  7. Naor

    Naor Guest

  8. WLD_Bill

    WLD_Bill Guest

    I just ordered a (4) piece lot of the STK433-330. I'm quite sure it will be fine. I will have 3 extras if you want to purchase 1 from me. I'm not sure when they will arrive.
     
  9. WLD_Bill

    WLD_Bill Guest

    Did you check the voltage outputs of the amp of the (7) protection circuit resistors? They are the white large cement (ceramic) type.

    Download the datasheet and it will demystify the the circuit and how it works.
    I found it quite interesting, especially the 8 bit code to the MCU stuff that Mark Z explained. I haven't delved much into that yet (just curious) The overvoltage protection circuit is neat how it puts the amps into standby mode, etc..
     
  10. WLD_Bill

    WLD_Bill Guest

    Update: Amp IC on back order. looking at other sources.
     
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