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  1. dorke

    Technics SA-828 Receiver from 70s- Is it worth trying to save this aging patient?

    Well, Things like that can happen.:( Take out Q627 and measure it(diode test mode). Measure in-circuit (diode test mode) Q629.Q631,Q635 and D615.
  2. dorke

    Technics SA-828 Receiver from 70s- Is it worth trying to save this aging patient?

    O.K Put volume knob at minimum disconnect the speakers. Power -up the unit. First thing to check is for the fuse not to blow. After that check voltage on center pin of Z601 relative to GND (on the lowest DCV range possible). What do we get? Check voltages between Z601 center and side pins...
  3. dorke

    Amp In Protection Mode

    Rick, The reading you get on R623 in #92 are wrong, could you please confirm them(relative to GND). Please measure DCV ,in the lowest range possible with both probes on both resistor legs: R623,R624 R621,R622 R607,R608 R617,R618 a total of 8 measurements.
  4. dorke

    Technics SA-828 Receiver from 70s- Is it worth trying to save this aging patient?

    Soldering could be better. Red - too much solder re-touch needed(remove excess with braid and re-solder) Green- remove solder splashes, take care not to lose them,we don't want them wondering around in the receiver. Clean well with cotton swab and rubbing alcohol . Blue - mechanical post ,do...
  5. dorke

    Amp In Protection Mode

    No, It will be tested with the original Q601/603(they are confirmed good after cleaning in the good channel) gradually,first without Q605/Q607 , then with them, and then adjusted. Let's see what more surprises await us... ;)
  6. dorke

    Amp In Protection Mode

    Sunnysky, The note meant R627 is part of the left(bad channel) and has no effect on the right(good) channel-in which both Trs 603 /604 are tested. On the right channel R628 is connected normally. Both Q603(cleaned) and Q604 work properly on the right(good) channel.,hence they are both fine
  7. dorke

    Amp In Protection Mode

    O.K Lets put Q602 back in it's original place. Please measure the voltages on: R622 R646,R648(should be in the mV range). R624(should be zero). What do we get? Then, Please put back Q601 and Q603 in their original places, re-connect the lifted leg of R627 to GND . and measure the voltages on...
  8. dorke

    Amp In Protection Mode

    I assume that "reads nothing" you mean zero volts? Q606/Q608 readings are exactly as they should be. All that means Q603 and Q601 are both fine! Did you have to clean Q601 as well?
  9. dorke

    Amp In Protection Mode

    When testing the "good" channel it has no effect,you can leave it not connected when putting Q603 in the place of Q604. Have you cleaned it well? When you take out Q604 ,please take a photo of it's bottom.
  10. dorke

    Technics SA-828 Receiver from 70s- Is it worth trying to save this aging patient?

    They are fine , Install them(a clear photo could help), After you have installed the Tr's, measure the resistance between the center pin(collector) to chassis GND,it should be very high(Mohms O.L)) Don't connect speakers to the left channel ! Power -up the unit with volume knob at minimum...
  11. dorke

    Technics SA-828 Receiver from 70s- Is it worth trying to save this aging patient?

    I would replace the bath wings on the left channel only. Do you have the insulator and thermal paste? Test the Tr's in diode test before assembly(just in case...) Note: after you install the Tr's don't connect speakers to the left channel ! First check that the fuse doesn't blow, then we should...
  12. dorke

    Amp In Protection Mode

    Rick, I would go with Edd's and Sunnysky's suggestion at this stage: replacing the Trs from the bad channel and inserting them in the good one, after they are cleaned well(photo?). but first inspect Q601 visually for corrosion etc. and please measure the voltages relative to Gnd on the output...
  13. dorke

    Technics SA-828 Receiver from 70s- Is it worth trying to save this aging patient?

    Welcome back Iceman , Did the "bat-wings" arrive already? Can the Receiver produce sound using phono or CD source at low volume (right channel only)?
  14. dorke

    Amp In Protection Mode

    Rick , I see dirt and corrosion on Q603 /Q065(or could it be a flash return?). This should be scraped well and cleaned with rubbing alcohol till it is shiny(black plastic and silver legs). What is the state of Q601?
  15. dorke

    Amp In Protection Mode

    Do you think it would pass diode test and still be faulty?
  16. dorke

    Amp In Protection Mode

    I wonder where did that 0.662 C-E of Q607 disappeared? could be a short during testing. At this point it is time to take Q603 out of the board and check it in diode test mode(6 measurements). Edit: Test Q603 in ohm test as well. Please post a clear photo of the bottom (legs side of Q603,Q605...
  17. dorke

    Amp In Protection Mode

    O.K. Looks like Q607 is fine as well. The situation we have now is Q605,Q607 out of board and R627 Leg lifted and not connected to anything,correct? If so, please check at the location on the board of Q607 C,E in diode test (please note the color of the probes when measuring) and then in ohm...
  18. dorke

    Amp In Protection Mode

    O.k so we have for Q605 diode mode readings (off the board) B - E .692 & nothing B - C .662 & nothing E - C nothing & nothing If so Q605 is fine. What about the C-E of Q607 of 0.662,can you verify that? If you still get that 0.662 take Q607 out of the board(mark/note it's orientation for...
  19. dorke

    Amp In Protection Mode

    Please verify the 0.653 E-C reading of Q605, If it is indeed 0.653 we have a bad Tr !
  20. dorke

    Amp In Protection Mode

    Not entierly. In normal condition Vb of Q603 should be 1.3V and a Vbe of 0.6V is the normal condition. Once we have the results at #54 we would test Q603 as well.
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