Pioneer help for noob...

Discussion in 'Pioneer Audio' started by arcspark, Feb 3, 2018.

  1. arcspark

    arcspark New Member

    Messages:
    29
    Hopin somebody can provide some steerage for me...long time fan of ak some posts years ago but now im at it again....my original sx424 from college days has been idle for long time but decided to fire it up again and yesterday when i turned it on it clicked like the protect circuit is working but for the first time ever....no lights anywhere...so not wanting to do the wrong thing can anybody advise some steps to check this out...slowly as im a noob but might be able to follow directions...at least i could explain it to somebody else who does undedstand if i have to...thanks for listening, arc
     
  2. arcspark

    arcspark New Member

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    29
    Not yet....ok
     
  3. zebulon1

    zebulon1 Getting behind on work. I need help? Subscriber

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    4,257
    Location:
    Las Vegas Nevada
    It needs a good Deoxit treatment.
    Plug it back in and select the FM tuner. Spin the dial and see if the signal meters work. Tune in a station.
    The dial lighting works when you are in FM or AM. Off when in another function.
     
  4. arcspark

    arcspark New Member

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    Well i wish it was that simple but i must not be getting power on thru. Does not light up at all regardless of function switch. Will have to look closer at things....
     
  5. Cuppy

    Cuppy AK Subscriber Subscriber

    Messages:
    183
    Location:
    Maine
    It looks like there is a 3 amp fuse from the transformer secondary that feeds the dial lamps and dial pointer. You will have to pull the cover and bottom panel and try to locate.
     
  6. Noodle

    Noodle LISTEN! I smell Hi-Fi. Subscriber

    Messages:
    519
    Location:
    Heart of Dixie
    What's worse is the 424 has no protection circuit, sounds like the main fuse popped, if you heard a click.
     
  7. arcspark

    arcspark New Member

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    29
    Was aware of being careful of not crossing any stray speaker wire...hasnt been problem for 40 years...for what its worth it clicks everytime i turn it on...just like my sx 650 that works fine...any thoughts?
     
  8. Cuppy

    Cuppy AK Subscriber Subscriber

    Messages:
    183
    Location:
    Maine
    Can you be more specific as to what is not working? Is the issue just the lights or is nothing functional? Hooked up to speakers, headphones?
     
  9. markthefixer

    markthefixer On Hiatus, dealing with Dad's estate full time Subscriber

    Messages:
    20,889
    Location:
    Bensenville,Illinois
    The 424 has two protection type (L & R) FUSES in the power amp's power circuit, located on the back panel.

    Does the click come out of the speakers or out of the body of the 424?

    The speaker outputs from the power amp are capacitor coupled, there is NO mechanical type motion in the 424 for a body type click other than that of the rotary power / speaker select switch itself.

    To run the unit, there are two fuses, a 1 amp fuse on the power line side of the power transformer, located on the back panel by the power cord and a 3 amp lighting circuit fuse, the old long filaments in the lamps COULD have been shorted internally with the jarring of any movement during removal from storage.

    follow pin 32 of the af unit awk-014 back to the blue wire out of the transformer, the 3 amp fuse is somewhere in between. Losing that fuse costs the five dial scale lights, the signal meter light, the dial pointer light and the stereo light. ONLY. No other power supply voltages involved.

    You are going to be replacing electrolytic capacitors:
    This unit has PLENTY old sky blue sanyo electrolytic capacitors on the AF unit, awk-014 that are guaranteed failures!! I suspect that even when unpowered they continue to deteriorate.

    The other old electrolytic capacitors in it are just as vulnerable, even though unpowered, time marches on and water escapes through the seals on the caps.

    While you are in there (it's an easy unit to work on) a few transistors could benefit from being replaced.
     
    Last edited: Feb 4, 2018
    slimecity likes this.
  10. arcspark

    arcspark New Member

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    29
    Thanks to everyone for yoúr replìès....mark thanks i do believe its just the switch clicking....will start to work in to it shortly... its great to have talent at your side when i need it....thanks arc
     
  11. arcspark

    arcspark New Member

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    29
    Well here it goes in baby steps.... so far the covers are off, the 3v fuse in the protective tube is easy to see and it tests for continuity...also down on the leads to the fuse....receptacles on back both work properly and it plays my cd player on aux and headphones too so it seems its just not lighting up when on...i noticed the phono ground is toast prob from years ago...needs resoldered. 3v fuse tests good so now where do i turn? Thanks arc
     
  12. arcspark

    arcspark New Member

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    29
    Sorry meant 3a fuse....any takers????
     
  13. slimecity

    slimecity Super Member

    Messages:
    2,170
    Location:
    New Zealand
    So by saying this you mean that you are getting sound thru the speakers on some inputs? Just not phono?

    If this is the case, just sounds like you need to replace the lighting bulbs - see Marks post above on the bulbs and the lighting circuit
     
  14. markthefixer

    markthefixer On Hiatus, dealing with Dad's estate full time Subscriber

    Messages:
    20,889
    Location:
    Bensenville,Illinois
    He / You might be running into a Pioneer "last chance" factory modification fuse - they had a lot of Darwin award candidates back then bypassing the formal, mounted 1 amp power fuse in the back panel with stuff like aluminum foil, so they added a last chance unknown and hard to tamper with inline fuse. I think he's seeing that because:
    IF the fuse is EXPLICITLY connected to a BLUE transformer wire on one side and pin 32 of the "AF UNIT" on the other, that IS the lamp fuse (posting pictures would help!!) otherwise, NOT!!!

    We NEED to know the exact model: KUW, FVZW, KCW, FW, NBW please!! Look on the serial number plate in the back.

    While loosing the fragile fuse style five dial scale lights and signal meter light is plausible, the dial pointer light and the stereo light are far more robust.

    note: any DMM probing MUST have all but the tiniest portion of the tip of the DMM probe insulated, "scotch" tape will do. You won't short things when you shift your eyes to read the meter and the probe slips. WE ALL SLIP!!!! No bs...

    Check for 8volts AC (not dc!!) at a lamp position.
    Connect your BLACK DMM probe to one side of a fuse type lamp
    Set your DMM to read up to 20v AC... I repeat AC...
    touch your RED DMM probe to the OTHER side of THE SAME fuse type lamp
    7 to 8 volts AC means the lamps SHOULD be working.

    If you cannot easily get TO a lamp to measure, then do this:

    Connect your BLACK DMM probe to a bare metal chassis ground.
    set the DMM to read up to 20v DC
    touch your RED DMM probe to pin 31 of the AWK-014 or AWK-018 "AF UNIT" pc board
    if there is +10v DC or so there, the lamp power is ON, this is the voltage that runs the stereo lamp.
     
  15. arcspark

    arcspark New Member

    Messages:
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    Mark...ok here goes...got a test at signal meter light holder, blue wire shows read of 7.8, purple side 5.0, also bulb is burned out....that might explain one,...... tested at pin 31 dcv and got 11.16 which seems good?....beginning to wonder if damn bulbs are just burned out and unit is intact....test lead pic shows dcv test location ..havent found how to get to other bulbs yet....any thoughts and thank you...also its a kuw series...arc
     

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  16. Eldin

    Eldin Active Member

    Messages:
    111
    Location:
    Grand Rapids, MI
    The blubs could easily all just be burned out. I you have a way to measure the DC offset of the unit, try that. If they pass hook up a pair of speakers and see what happens. I know the sx737 and sx636 have a pair of very troublesome transistors (forgot the model). If you hear crackling and snapping they are likely the cause.

    I've bought a "faulty" receiver in the past that worked just fine, just needed new bulbs.
     
  17. arcspark

    arcspark New Member

    Messages:
    29
    Yea, its playin thru aux and headphones so im thinkin it could just be lights....have not hooked up tuner yet....got to find a light package....thnks arc
     
  18. markthefixer

    markthefixer On Hiatus, dealing with Dad's estate full time Subscriber

    Messages:
    20,889
    Location:
    Bensenville,Illinois
    The measurements you took are sufficient to confirm that the lighting circuit IS powered up. You would find the same voltages at the other sockets.

    Yes, you need new lights.

    This unit is old enough to escape most "troublesome" transistor parts numbers, but there are 8 CSSA capacitors on the AWK-014 (or -018) AF unit that will develop problems eventually.
     
  19. arcspark

    arcspark New Member

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    Thank you all for listening...mark, today was sorta exciting...new led fuse lights 5 in dial and 1 in signal meter and ...wait for it ...the dial lit up but the sm bulb, 2.tried.., Isn't lit and l don't have the wheat bulbs yet for pointer so it's still out...(hate that one)...yet the numbers seemed good at the sm holder....any thoughts and steerage? Thank you.arc
    .
     
  20. arcspark

    arcspark New Member

    Messages:
    29
    My bad..... switch has to be on tuner for that light....whoo we got one more to go...it looks as good as the day I brought it home 46 years ago
     

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