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Yamaha rxv 465 no display and no power..

Discussion in 'Troubleshooting and Repair' started by Hemant Choudhary, May 1, 2018.

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  1. Hemant Choudhary

    Hemant Choudhary

    49
    1
    Nov 1, 2016
    Hi,

    I am looking here to find some help regarding yamaha rxv465.

    The problem is..when turned on, there are only relay clicks and nothing.

    No display as well.

    I had this unit from my friend with eagerness to get it repaired it by myself.

    Please help me trying to go ahead with the troubleshooting.

    Regards,
    Hemant.
     
  2. kellys_eye

    kellys_eye

    4,276
    1,146
    Jun 25, 2010
    What test equipment do you possess? What are your skill levels in repairing such equipment?
    Have you found a service manual for it (schematic etc)?

    We can assist with repairs but these may be beyond your skill set unless you confirm otherwise.
     
  3. Hemant Choudhary

    Hemant Choudhary

    49
    1
    Nov 1, 2016
    Hey Thanks,

    i have fairly good soldering technique, have test instrument like DMM.

    i have fair amount of understanding with analog amplifiers and have been repairing them as its my liking..(hobby).

    i have all required instruments except oscilloscope.

    also, i have the schematic.

    Regards,
     
  4. kellys_eye

    kellys_eye

    4,276
    1,146
    Jun 25, 2010
    Please post the schematic (or link to one)
     
  5. Hemant Choudhary

    Hemant Choudhary

    49
    1
    Nov 1, 2016
    Further updates as below;

    There is a good amt of dc offset voltages at the emmiter resistor's middle pin..aprox 3 to 5 volts, this is for the very short duration when the first relay clicks.

    Also noted, the input supply rails have plus minus 24 rather than 50 volts as in the schematic.

    Is the dc voltage at the output due to low voltages in the supply of the STK.

    Please assist,

    Regards,
     
  6. 73's de Edd

    73's de Edd

    2,848
    1,209
    Aug 21, 2015
    Sir Hemant Choudhary . . . . .

    That systems dual polarity, DUAL LEVEL power supply shifts up from the low level, which you currently have, to the full supply level after the filters take on their initial charge.
    This is being accomplished by RY100 and its Q1016 driver, at the top of the power supply schematic via command from Q1015.

    However . . . . it seems that you have a circuit fault, so the supply never steps up to that full secondary value.

    This units problem should be what I was sort of expecting to be the fault on your previous unit.

    Consult page 117 of the schematic . . . . .

    Then you locate your top STK433-130 power amp module, used for the SURROUND Right and Left channels.

    The lower STK433-330 is responsible for the MAIN R and L channels PLUS the extra burden of the center channel.

    Inside of the power modules each channel has a pair of output transistors stacked between the Plus 50 and Minus 50 supplies.
    If all is well within the module, the voltages balance out and there is a static cancelling out and almost zero volts DC normally being at their outputs, which fed to their speakers.*****

    Then, as audio is applied to a channel, a coincidental voltage swing to the waveform is replicated at the output of the module . . . all in accordance as to how high you have the volume advanced..

    These modules are sampled for the current consumed by them, the peak voltage swing that they produce ( in case you have no speakers connected, and you then run the volume to max, since you heard nothing ?)
    And finally, the the DC voltage at the output to the speaker, of each amp, as I previously related to in *****.

    Let's start by having you look at the right edge of the schematic and work from top to bottom in locating the separate sensing transistors Q1007---Q1008---Q1012---Q1011 and Q1006.
    Those transistors bases are sampling each channel and the outputs off all of the sampling transistors are collectively fed into Q1013 base, so that fi8nal transistor can respond if any fault is found on any the 5 tracked stages.
    There are also being two additional clusters of fault finding circuitry, but lets start with the just mentioned one first.

    Connect DC voltage metering with the negative lead to anywhere on the heavy black ground buss.

    Positive meter lead, will be going in a testing sequence, to the separate bases of Q1007---Q1008---Q1012---Q1011 and Q1006.

    You turn on the set and notice the max voltage reading experienced , just for that instant, and log down.
    Then you power down and move on to the next transistor.

    Give back the voltages and we will see where we need to go next.

    73's de Edd
    ....
     
  7. Hemant Choudhary

    Hemant Choudhary

    49
    1
    Nov 1, 2016
    Hi,

    i am sorry that i could not post this earlier.

    Here are the readings taken from the respective bases

    Q1007= 3.3
    Q1008=3.9
    Q1012 =2.8
    Q1011=2.9
    Q1006=1.3v

    And 1013=37volts.
     
  8. Hemant Choudhary

    Hemant Choudhary

    49
    1
    Nov 1, 2016
    Hi,

    Just a doubt..shall we check for the power supply at the secondary of the main transformer as to why we are getting half the voltages at the supply inputs to STKs?
     
  9. 73's de Edd

    73's de Edd

    2,848
    1,209
    Aug 21, 2015
    Sir Hemant Choudhary . . . . .

    With those voltage levels being read, looks like a serious imbalance in one of your STK power amps has occurred and the Power Relay Timeout is feeding back to the U/p to shut the system down.

    With it having 3 sections, the STK433-330E pulls the most power so lets try that one first.
    It seems like all of the sense transistors sort of interfeed their voltages by virtue of their interconnected 47k resistors to the base of the Q10213 PRT switching transistor.

    Go to Q100 . . .STK433-330E, and count off its pins #1 and #3 and solder suck and / or solder wick + rosin flux to get those pins floating and free from their surrounding pads. Do a VERY-VERY gentle ohms check from each freed pin to its pad ,
    for there being no ohmmic continuity . . . . thus, assuring that both are floating from connecting to their power supplies feeds..

    Then power up and do the same sensing transistors voltage testing , hoping that the same unwanted voltage level is NOT still being there.

    If no voltage is there, then you can power up and test the R&L surround channel with speakers, as they should now work.

    If you found the sense voltages still being present, float the pins 1 & 3 of the STK433-130E, and then test its sense transistors, expecting it to be the bad unit.
    ? If you then found it to be THE bad one ?

    Then you could leave its power input pins floating, and go back and solder back the pins of the first -330 that you tested and give it a speakers test.

    WORST case, is if you find both units bad . . . . I'm not expecting that.

    Thasssssit . . . .

    73's de Edd
    .....
     
  10. Hemant Choudhary

    Hemant Choudhary

    49
    1
    Nov 1, 2016
    Sir de Edd,

    Below are the details of the findings done with pins 1 and 3 removed as per the process discribed by you above.

    Now there is only some milivolts not more than .5volts (DVM range 20 volts) on all the sensing transistors.

    One thing to note here which i found today is the amp_olv is not 1.5v but rather in 0.5v or less, even during the power up and down.

    Now, tracing for this loss in voltage...

    Please guide..
     
  11. Hemant Choudhary

    Hemant Choudhary

    49
    1
    Nov 1, 2016
    Further, the unit still turns off after few seconds..
     
  12. 73's de Edd

    73's de Edd

    2,848
    1,209
    Aug 21, 2015
    Sir Hemant Choudhary . . . . .

    Fine now, with there not being any excessive DC voltage on the multiple voltage sensing transistors that you just tested..

    Now lets see why there is only being that short temporary power relay action, and it not latching, and staying on.
    But you DO need to know your relays, as there is one related to basic AC power on, another for initially switching a timed charge up between two DC power levels, and a third relay that disconnects the units speakers .
    The last one, to keep an errant + or - 49VDC continual presence, from cooking the voice coils of your speakers.

    Look down to the left corner of page 117 schematic where are Q1001 and Q1002 power switching transistors that will both conduct, in order to switch on the + and - 49VDC power to the power amp modules.
    A 2SB1274 is used for the +49 VDC supply with conduction from emitter to collector . . . IF . . . Q1003 so permits it.
    A sampled voltage from R1008-R1009 junction to Q1004 enables the -49 VDC supply, . . .IF . . . the +49 supply is initially activated and not overloaded .
    Base voltage status of the Q1003, then determines if both supplies are to disconnect, due to a detected fault.

    Now . . . . meter the presence of + and - 49 VDC voltages at the emitter of Q1001, and the collector of Q1002 to see if those voltages stay there past initial power up and for the next 15 seconds, or does it abruptly just drop off .
    If the voltages stays on for both supplies, then move metering to the collector of Q1001 and the emitter of Q1002, to see if those +49 and -49 then switch off. . . . just as your unit is now doing, by staying on but for just a few seconds ?

    Now referring to far right center portion of the schematic . . . . .

    In addition to the above power related sections, your units OV_L sensing is yet another of the 3 potential lockout / fault features, still needing to be tested.

    You can also jump ahead to testing that portion by measuring across Q1014's base and emitter to see what + voltage is being there. Initially In the power standby position, and just after you "try" to power up the unit

    It's being similar to the other test just done BUT they were smart / extravagant enough to use D1010-1014 steering / isolation diodes in this circuitry, and it thereby isolates and more directly points out the source of the problem.
    On the other test . . . that you had just done . . . all of the voltages were being " mixed" together due to multiple tied together 47K resistors.

    ( Akin to . . who was the one person in the large crowd of shouters, that just shouted out a profanity ? )

    Test-test-time

    73's de Edd
    .....
     
  13. Hemant Choudhary

    Hemant Choudhary

    49
    1
    Nov 1, 2016
    Hi,

    With pins 1 and 3 removed the further tests were done.

    First, the emitter of Q1001 plus 37 volts
    Collector Q1002 minus 37 volts, both these voltages drop very very slowly.

    Now collector of Q1001 and emitter of Q1002, the voltages do switch from their respective sides but as soon as the closing relay clcks..this drops very fast.

    The base of Q1014 has 1.6volts when on.

    Please guide..

    Regards,
     
  14. Hemant Choudhary

    Hemant Choudhary

    49
    1
    Nov 1, 2016
    Hi,

    With pins 1 and 3 removed the further tests were done.

    First, the emitter of Q1001 plus 37 volts
    Collector Q1002 minus 37 volts, both these voltages drop very very slowly.

    Now collector of Q1001 and emitter of Q1002, the voltages do switch from their respective sides but as soon as the closing relay clcks..this drops very fast.

    Also, with every starting click of the relay these voltages rise with a step of 3 v, till it reaches 39 volts.

    The base of Q1014 has 1.6volts when on.

    Please guide..

    Regards,
     
  15. Hemant Choudhary

    Hemant Choudhary

    49
    1
    Nov 1, 2016
    Please note,

    I removed the μp board while tracing the +3.3S supply and found that the transistor Q201 is missing.

    I think this unit is already worked by someone but thats not my problem, as i am trying to learn more of these recievers of today.

    Regards,
     
  16. 73's de Edd

    73's de Edd

    2,848
    1,209
    Aug 21, 2015
    Sir Hermant . . .

    Reference to page 112 VERY TOP , just right off center for the 3.3 VDC main supply and this circuitry which is providing SWITCHED 3.3 VDC

    In your inspecting of the the missing transistor pcb foil tabs, does it definitely show tell tale solder remnants that suggest of a prior pulling of that transistor?

    Q201's purpose is to be an interfacing digital transistor with its low power and internal resistors that is receiving a high signal from the U20 u/p pin #26 and it then activates the gate of the Q200 power switching FET, and 3.3 VDC leaves from its Drain lead as a switched power source..
    Now . . . . .is the Q200 still there ?

    This 3.3VDC switched supply only seems to relate to some mute functions of the tuner portion .

    73's de Edd
    .....
     
  17. Hemant Choudhary

    Hemant Choudhary

    49
    1
    Nov 1, 2016
    Apart from the missing transistor, what will be the next step moving further.

    I will confirm the presence of the Q200.

    Pin 1 and 3 of both STKs have been resoldered.

    Regards,
     
  18. Hemant Choudhary

    Hemant Choudhary

    49
    1
    Nov 1, 2016
    FET Q200 is present in the ckt.
     
  19. Hemant Choudhary

    Hemant Choudhary

    49
    1
    Nov 1, 2016
    Some readings of CB23 are as below,
    Sp_imp ..3.3
    Ps1_PRT 0.06
    AMP_LMT 1.12
    AMP_OLV 0.01
    I_PRT 0.01
    DC_PRT 0.02
    VOL_SCK 0.0
    DGNG 0.0
    VOL_MOSI 0.0
    MUTE_SW --10.8V

    MUTE Z3 and Z2 are 0 volts

    Please somebody assist, if the above readings can provide any clue to move forward.
     
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