Pioneer SX-1500TD reciever help

Discussion in 'Pioneer Audio' started by MadeMine, Feb 8, 2014.

  1. MadeMine

    MadeMine Active Member

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    164
    Can anyone give me any advice on where I should start to trouble shoot this right channel not working?
     
  2. MadeMine

    MadeMine Active Member

    Messages:
    164
    Sure would like to give this old beaut a second chance that I saved from being scrapped, and troubleshoot the right channel problem. I'm clueless where to start besides what Zebulon1 gave me.

    It sure would be interesting to find out whats wrong with it.
     
  3. MadeMine

    MadeMine Active Member

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    164
    I singly wired the Left and Right Pre-Amp out to the Main-Amp in, with the separate switch on.

    Left pre-amp out worked on main amp in on left side only.

    Right pre-amp out worked on main amp in on left side only.

    May be this can help to start a trouble shooting process.

    Is the problem in the main amp in?
     
  4. petehall347

    petehall347 the brandy coffee man

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    Location:
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    seems like its the main amp . did you pull the fuse on the amp board and test it ?
    what voltage at the fuse ?
    and voltage at c14 + side ? should be half of what it is at fuse .
     
  5. MadeMine

    MadeMine Active Member

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    164
    Thanks Pete, All fuses are good. I can't seem to get a good voltage measurement across the fuse or C14.

    What am I missing?
     
  6. blhagstrom

    blhagstrom Mad Scientist, fixer. Subscriber

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    Location:
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    I didn't have to fix my SX-1500TD, but here are some general repair processes I use on the old receivers.

    It appears you have isolated the issue to the main amp.

    Pull the output transistors and do a diode test on them.
    Then back through the signal path, pulling and testing transistors.
    Drivers, Pre-drivers, etc... Usually a dead amp has problems at the outputs and close by. But, anything is possible.

    Test the resistors. Emitter resistors on the outputs are typical problem children.

    A dead channel on an amp is usually due to a blown output transistor and perhaps a few parts close by. (But, I've seen amps that were tore up from front to back, so keep your eyes pealed for toasted resistors, blown transistors, blown diodes).
     
  7. petehall347

    petehall347 the brandy coffee man

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    not across them but reference ground ..black test lead on shiny chassis .red on test point
     
  8. MadeMine

    MadeMine Active Member

    Messages:
    164
    Thanks Pete,

    I measured the AC volts at 600 on the fuses and they are 190 on both.

    I measured the AC volts on the 4 large capacitors at the same 600 setting they were all 80 volts, except 1 that was 0 volts, this one is wire to the board and joins C14. I took a closer look at it and it has a small hole in the top.

    What should I do next?
     
  9. petehall347

    petehall347 the brandy coffee man

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    set your meter on dc volts and measure again where i first said
     
  10. MadeMine

    MadeMine Active Member

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    164
    Thanks Pete,

    I measured the DC volts at 600 on the fuses and they are 89 on both.

    C14 had -35 volts and the capacitor wire to it had 0.
     
  11. petehall347

    petehall347 the brandy coffee man

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    i don't understand what you mean by capacitor wire ?
    next measure dc mv across r32 and r34 0.5 ohm 2 separate readings . expect around 10mv or so .
     
  12. MadeMine

    MadeMine Active Member

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    164
    C14 has another capacitor wired to it, its mounted on the chassis, Its the same size capacitor as c14.

    Multimeter on dc mv, r32 measured -32.5 .
     
  13. petehall347

    petehall347 the brandy coffee man

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    try playing some music and connect in1 and in2 together with a length of wire and see if sound then comes out from both speakers .

    32.5mv seems a bit high also measure r31 r33 r34 to compare ..
     
  14. MadeMine

    MadeMine Active Member

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    164
    music is heard when in1 and in2 work when wired together.

    I was testing r31 and zapped something and blew the left fuse. I put the right fuse in the the left fuse slot and it blew. Now what shall I do?
     
  15. petehall347

    petehall347 the brandy coffee man

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    Location:
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    shit ...looks like you blew a transistor .. q9 or q11 or both .. pull them out and check them ..
    plus side the main amp was working and the problem is before it ...if that could be a plus side now ..
     
  16. MadeMine

    MadeMine Active Member

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    164
    Thanks Pete, I checked out the transistors and found the 2SC497 bad.

    When I order these what part number should I use?

    This is the first time I have attempted doing any of this except soldering a board on another pioneer. Great brain exercise.
     
  17. petehall347

    petehall347 the brandy coffee man

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    did you check them out of circuit ?
    did you check the outputs 2sd218?
    i would be inclined to replace with original numbers .only because i can get them cheap here ..where are you ?
    there will be subs i will check for something more modern .
     
  18. petehall347

    petehall347 the brandy coffee man

    Messages:
    23,508
    Location:
    uk.. the middle bit
  19. petehall347

    petehall347 the brandy coffee man

    Messages:
    23,508
    Location:
    uk.. the middle bit
  20. MadeMine

    MadeMine Active Member

    Messages:
    164
    Thanks Pete, I'm still working on removing the transistors. I checked before while they were in didn't know better. Both of the 2SC458LG are good. I'm moving on to the next six 2sc497. I've also been taking crash studies on NPN Base, emitter, and controller. I'm catching on to it. Oh yea live in Colorado.
     

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