Technics SU-VX800 amplifier

Discussion in 'Technical Repair' started by Marius83, Dec 28, 2017.

  1. MrChips

    Moderator

    Oct 2, 2009
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    @Marius83
    I am inclined to go with RC4558P or NE5532AP.

    While you're at it, you should buy some 8-pin DIP sockets and some 8.2V 500mW zener diodes, 1N756 or 1N5237.
     
  2. Marius83

    Thread Starter Member

    Dec 28, 2017
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    Thanks! :)
    I will get the supplies!
     
  3. MrChips

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    Let's keep our fingers crossed that this is the last stop for supplies. But you can never tell. I am well aware that we still have many components to go back in and you also had an issue with smoking from the front panel.
     
  4. Marius83

    Thread Starter Member

    Dec 28, 2017
    52
    1
    Hehe, yes you are correct about the front panel. Time will show :)

    I have now ordered supplies.
    We'll just have to wait again :)
     
  5. MrChips

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    I wonder how many folks are sitting on the fence watching this show. It would be interesting to know. This is as exciting as watching paint dry. Or waiting to see me hang myself.:)

    Maybe we should ask everyone following this saga to sign in just for the record.

    Where is @R!f@@ when he's wanted? Hope he's not behind bars.:eek:
     
    hrs and DbLoud120 like this.
  6. JoeJester

    AAC Fanatic!

    Apr 26, 2005
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    3850 views ... so, you can draw some conclusion. I've viewed it probably 3x the number of postings at a minimum.
     
  7. MrChips

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    First time drive-by visits don't count. I want to know who is anxiously waiting for the next episode to be aired, while following the cookie crumb trail with a printed copy of the circuit schematics in front of them, like trying on unravel one of Murdoch Mysteries.:D
     
  8. JoeJester

    AAC Fanatic!

    Apr 26, 2005
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    @MrChips, I'm following your adventure. Only difference is, I have that section simulated in TINA and about to put the next section into simulation.

    I'll have to go back and look at which component is smoking in the front panel ... I did come to the game late with only cursory views before page 3 turned into page 4.

    However, here is a "stitched" portion of the two pages so we don't have to work too hard on reading the circuits that may have been damaged by the C-E short .... Sometimes I just hate the way the diagrams are working these days.
     
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  9. MrChips

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    @JoeJester, I just cut and tape the sheets together and then I can mark up the paper as we go along. I am simulating on CircuitMaker 2000 as we proceed.

    Here is a summary of where we're at.

    1) C425 filter capacitor on the +60V line keeps popping. We've left it out for now until we get all the voltages correct and stabilized.

    2) LEFT CHANNEL was blown accidentally. I think we have that stabilized. Q507-Q509 complementary output pair are in place. Q515-Q517 pair have been removed for now. DC balance not yet adjusted. Will do that later.

    3) LEFT & RIGHT CHANNEL outputs from preamp have been disconnected. Inputs to power amp are currently grounded.

    4) On RIGHT CHANNEL, Q406, D412, Q416 identified as blown. Waiting for more supplies to arrive. The plan is to replace Q406, Q408, D410, D412, Q416, IC402.

    5) Still to come, replace Q420, Q424, Q426, Q428, Q430.

    6) Still to come, check DC levels from preamp.

    7) Still to come, check possible fault on front panel.
     
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