Pioneer SX 828 recapped - Relay click on and off

Discussion in 'Pioneer Audio' started by havols, Apr 23, 2017.

  1. havols

    havols Active Member

    Messages:
    133
    Location:
    Manaus, Brazil
    Thanks Les.
    I will search new transistors, and replace Q1, Q2, Q3 &Q4
    A good equivalent to 2SC857K is the SC2310? And 2SC945 is the SC2383?
    Regards
    Havols
     
  2. LesE

    LesE 110284 Subscriber

    Messages:
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    Location:
    Ontario, Canada
    KSC1845 is commonly recommended for the replacement of Q1 & Q2. 2SC2310 has a higher Ft (100 vs 50 Mhz for the C857) but it otherwise looks suitable.

    I have also used KSC2383 as a replacement for Q3 & Q4 so 2SC2383 should be fine.

    Hopefully, others will chime in if there are concerns with these replacements.

    As always, it is advisable to use a DBT with minimum volume and speakers disconnected following any changes.

    I did a quick scan through this thread and it may have already been mentioned but did this protection problem exist before the recap or only after?

    Les.
     
  3. havols

    havols Active Member

    Messages:
    133
    Location:
    Manaus, Brazil
    Thanks Les
    The protection problem exist before recap. This is why i decided recap the receiver.
    I will look for new transistors. I hope find here.....
    After installed, post results.
    i use DBT too. Learned here in Audiokarma.
    Thank you all
    Havols
     
  4. zebulon1

    zebulon1 Cleaned up the shop and half finished sets. Subscriber

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    Can you post the protection board pin readings with the protection on and off for Pins:
    5, 6, 7, and 8?
    Then pins 1 and 3?
    It's a big chore but the protection is sensing something.
     
  5. havols

    havols Active Member

    Messages:
    133
    Location:
    Manaus, Brazil
    Zeb
    Now, the receiver stills only in protection mode.
    Readings:
    Pin 1: 1 mV
    Pin 3: 4.7 mV

    Pin 5: -11.5 mV
    Pin 6: 10.2 mV
    Pin 7: 3.2 mV
    Pin 8: -12.2 mV

    Havols
     
  6. zebulon1

    zebulon1 Cleaned up the shop and half finished sets. Subscriber

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    The protection board readings you posted look fine.
    The board needs to be rebuilt. Q1 and Q2 are suspect.

    This is the current rebuild list for the protection board:
    Protection Assembly (AWM-025)

    AWM-062-0: C1: .22uF 10v CSSA: 505-MKS20.22/63/5 .22uF 63v
    AWM-062-0: C2: .22uF 10v CSSA: 505-MKS20.22/63/5 .22uF 63v
    AWM-062-0: C3: 330uF 6.3v CEA: 647-UPW1A331MPD 330uF 10v
    AWM-062-0: C4: 330uF 6.3v CEA: 647-UPW1A331MPD 330uF 10v
    AWM-062-0: C5: 4.7uF 25v CEA: 647-UPW1V4R7MDD 4.7uF 35v
    AWM-062-0: C6: 100uF 16v CEA: 647-UPW1E101MED 100uF 25v

    Q1: 2SC869: 512-KSC1845FTA
    Q2: 2SC869: 512-KSC1845FTA
    Q6: 2SC945: 512-KSC2383YTA
    Q7: 2SC1384: 512-KSC2690AYS
    1N4004 flyback diode is added between pins 9 (anode +) and 10 (cathode -)

    This is the troubleshooting procedure I use for checking the protection boards.
    Courtesy Mark aka "MTF".
    Backwards troubleshooting procedure:

    Remove q6 and q5 , power up unit, relay should click after time delay.

    Install q6, relay should still click after time delay, also now when fuse supplying 7.5v ac to pin 12 is pulled, relay should click out, and when fuse reinstalled, wait time delay and click in.

    Before installing q5, lift the cathodes of d5, d6 and d7, then install q5.
    It should continue to operate as per q6 step above.

    While the relay is pulled in, ground d5 cathode momentarily (150k ohm R18 does good job current limiting - so no danger) and see that relay "protects / releases" with time delay before reengagement. do the same for d6 and then again for d7

    Now reinstall d5, this is the overcurrent "input" for the protect. The relay should still pull in - as we have no audio going out and no speakers connected.
    If the relay does not pull in, we need to look at (just plain replace) the two over current sensing transistors, one per channel and in some cases maybe on the amplifier card.

    Reinstall d6 and d7 as a pair. this is the DC detect circuit. The relay should still pull in - as we have no audio going out and no speakers connected.
    If not ok, (and pins 1 & 3 don't have over 50 mV on either of them) we need to lift R9 and R10 's pin 1 & 3 ends, and ground the hanging in the air leads to see if the dc detect circuit is behaving.


    One last thing:
    I'll remove the jumpers when securing the amps and protection boards. It removes the influence of the unrestored pre amp which has some troublesome transistors in it. If you haven't worked the pre-amp it's a good idea to have the two amps separated for the time being.
     
    Last edited: Oct 26, 2017
    havols likes this.
  7. havols

    havols Active Member

    Messages:
    133
    Location:
    Manaus, Brazil
    Thanks Zeb
    C1 and C2 are really 0.22uf?
    I am asking why AWM025-A scheme had 0.056uf Caps C1 and C2. But I have 0.22uf capacitors here, no problem to install them.

    I'll go buy itens until tomorrow.
    post results here
    Thanks a lot for the help.

    Havols
     
  8. zebulon1

    zebulon1 Cleaned up the shop and half finished sets. Subscriber

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    My scat says .22uf/10v
     
  9. havols

    havols Active Member

    Messages:
    133
    Location:
    Manaus, Brazil
    I am lookin' a AWM-025A from pioneer sa 9100 service
    I will use a 0.22uf now.
    Havols
     
  10. zebulon1

    zebulon1 Cleaned up the shop and half finished sets. Subscriber

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    Last edited: Oct 26, 2017
  11. havols

    havols Active Member

    Messages:
    133
    Location:
    Manaus, Brazil
    As I imagined by me, i can't find sa992 or 2sc1845.
    I only found one piece of 2sc2310

    Looking at the equivalents, I found that 2sc3467 could be used in place of 2sc857.
    Can the 2sc3467 replace the 2sc857 on the protection board?

    for sa992, I found a BC559, which is taken as a substitute of 2sa725.
    I found the rest of the pieces. I'll work on them soon enough.

    Regards
     
  12. WE6C

    WE6C Active Member

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  13. zebulon1

    zebulon1 Cleaned up the shop and half finished sets. Subscriber

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    I can send you some. It will be a wait but worth it.
     
  14. havols

    havols Active Member

    Messages:
    133
    Location:
    Manaus, Brazil
    Thanks Zeb
    I can't find here, in Manaus - Amazon - Brazil.
    But i think that i can buy it in other State of Brazil. But it will take about 30 days..
    Or, in christmas day, I'm going to visit my family in the RS state, and I can buy there
    One hour ago, I took a chance, because I've been with this receiver on the bench for a long time .....
    i replaced Q3, Q4 and Q5 by new one 2SC 2383
    Replaced C1 and C2 by new polyester cap 0.22uf X 63V
    AND REPLACED both 2sc857 by one 2sc2310 and one 2sc3467.
    And.... surprise..... Receiver works perfectly.... fine... great sound
    I listened for 50 minutes, in 40 % of total power.
    Sounds fine
    After 30 minutes, BIAS was R = 18mV & L = 26mV
    Offset is around 0v

    So now, i ask myself?
    Can i use 2SC3467 to replace both of 2sc 857 Q1 & Q2 on protection board? It is safe?
    Can you help-me?

    Many thanks to all who have helped me so far
    Havols
     
  15. LesE

    LesE 110284 Subscriber

    Messages:
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    Location:
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    Hopefully you didn't actually replace Q5 with a 2Sc2383 which is NPN. Q5 on AWM-025 needs to be PNP.
     
  16. havols

    havols Active Member

    Messages:
    133
    Location:
    Manaus, Brazil
    My mistake
    Q5 is really a 2sa733 PNP.
    Replaced Q6 = 2sc945. Q3 & Q4 as well.
    Sorry, my typo.
     
  17. zebulon1

    zebulon1 Cleaned up the shop and half finished sets. Subscriber

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    Hey:
    I was troubleshooting using the wrong scat (I was using the sx-1010 and the sx-828 scat, :confused:). The two protection boards are essentially the same circuit and the logic still works.
    The 2SC3467 is overkill but it's a good sub. I would like to have a stash of them for the NSA sets.
    Glad to hear you got it going!
     
  18. loweran

    loweran AK Subscriber Subscriber

    Messages:
    878
    Location:
    Austin, Texas
    Nice!!! Glad to hear you got it going!!
     
  19. loweran

    loweran AK Subscriber Subscriber

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    Location:
    Austin, Texas
    Havols, it must be our day. I have been working on an SA-7500II for a week and it was not cooperating. Narrowed it down to the relay and driver. New caps, new relay and new driver. Working like new!
     
  20. havols

    havols Active Member

    Messages:
    133
    Location:
    Manaus, Brazil
    Loweran
    Glad to hear that you got it too.
    I'm going to drink some beers tonight, and enjoy this sx 828.
    In the next few weeks I will finish my work on a pioneer pl-a30. This is not a fantastic record player, but forms a charming set with this pioneer sx-828, both in excellent conservation.

    Thanks to all of you who helped me fix the problems in this sx 828. Larry, Mark, Loweran, Zebulon, Les....
    Audiokarma is fantastic.
    Greetings from Brazil
    Havols
     

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