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sx 780

  1. C

    Pioneer SX-780 Voltage Regulator Trouble

    Hey all, I have an SX-780 that refuses to come out of protect. PA3001 isn't getting the 13.5 volts it needs to come out of protect, but there are more issues. Q25 - 2SD712 7.6v on emitter 7.2v on base 8v on collector Q13 - 2SD325R 25v on emitter 28v on base 25v on emitter C316 has the...
    • CaseyWKC
    • Thread
    • 2sd712 pioneer protection protection board regulators sx 780 voltage
    • Replies: 62
    • Forum: Pioneer Audio
  2. ajcoates

    SX-780 - help!

    Hey all! I just finished a full recap of my SX-780, including an upgrade to the discrete output packs that @rcs16 came up with. I also replaced the three heatsinked power supply transistors to modern lower-heat equivalents. It sounded great and tested perfectly last night, but this morning, the...
    • ajcoates
    • Thread
    • buzz through both speakers help pioneer pioneer buzzing sound pioneer sx 780 pioneer sx780 stk 0050 sx 780
    • Replies: 4
    • Forum: Pioneer Audio
  3. wayoutwest

    Great Match for Pioneer SX-780?

    From what I've seen, this thread has been done many times, so apologies right out the gate to beat a dead horse with so much information already out there. I recently bought a serviced SX-780 and am really pleased with it. I've been looking for proper speakers to pair with it, as I feel it...
    • wayoutwest
    • Thread
    • 70's pioneer solid state sx 780
    • Replies: 7
    • Forum: Speakers
  4. B

    Pioneer SX-780 restoration

    Hello, I have a question about an sx-780 I want to fix up. A little background on me, I've done some tube radios, both AM and one AM/FM. I'm familiar with basic soldering/desoldering, recapping, and limited troubleshooting. Use (in series) an isolation transformer, variac, and dim bulb tester...
    • breadtimesam
    • Thread
    • pioneer receiver solid state stereo sx 780 sx-780 sx780 tuner
    • Replies: 1
    • Forum: Pioneer Audio
  5. L

    SX-780 Darlington testing

    Hello all, I've been searching for a while and can't seem to find a detailed enough guide on how to test the Darlingtons on my sx 780. I blew a fuse (4A) in it a while ago, when I replaced the fuses, there are no longer the start up clicks. Are the darlingtons fried? or it is the protection...
  6. H

    SX 780 No output.

    Hello. I have power to the face lights, source light and tuning needle. No output from speakers. I checked the basics and then found this. In the pics are a brown wire that appears to have heated up/shorted out. Bare wire exposed and melted shield. The wire goes back to the transformer. There is...
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