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Pioneer SX 939 Repair and Restore

Discussion in 'Pioneer Audio' started by Spenser, May 26, 2018.

  1. Spenser

    Spenser AK Subscriber Subscriber

    Messages:
    402
    Location:
    Pittsburgh, PA, USA
    ...AND SO IT BEGINS.

    Pioneer SX-939 Inspection.jpg

    Pioneer SX 939 which is going into protection. This will be full restoration. I am planning on taking my time which means the project will go on for several weeks.

    Openning hypothesis: the issue that is causing it to go into protection could be something as simple as the 2SC1451 transistors in the Power Amplifier. Edit: could also be something in the protection circuit like a C5 changed in capacitance value due to age and wear.

    I've gone through and verified by visual inspecton what is actually installed (in the Power Supply, Protection Circuit and Power Amplifier).

    Can I get some help with my initial component selections? Let's start with the Power Supply (and then I am going to run by you also the Protection Circuit and Power Amplifier).

    Thanks!!!

    DRAFT DRAFT DRAFT -- DO NOT USE -- THIS LIST IS UNDER DEVELOPMENT!!!

    AWR-052-0 Power Supply
    AWR-052 C11 47uf 63v cea up it to 100V 647-UPW2A470MPD
    AWR-052 C12 47uf 50v cea up it to 100V 647-UPW2A470MPD
    AWR-052 C13 470uf 80v ach-038 up it to 100V 647-UPW2A471MHD
    AWR-052 C14 470uf 80v ach-038 up it to 100V 647-UPW2A471MHD
    AWR-052 C15 100uf 63v cea 647-UPW1J101MPD
    AWR-052 C16 100uf 63v cea 647-UPW1J101MPD
    AWR-052 C17 47uf 16v cea up it to 25V 647-UPW1E470MDD
    AWR-052 C18 47uf 16v cea up it to 25V 647-UPW1E470MDD
    AWR-052 C21 47uf 50v cea up it to 100V 647-UPW2A470MPD
    AWR-052 C22 2200uf 10v cea 647-UPW1A222MHD
    AWR-052 C23 220uf 16v cea 647-UPW1C221MPD
    AWR-052 C24 1000uf 35v ach-039 647-UPW1V102MHD

    Filter Caps

    C1 10000UF 50V up it to 12000uF 63V 647-LKS1J123MESC
    C2 10000UF 50V up it to 12000uF 63V 647-LKS1J123MESC

    Q1 2SD313 KSC2073 512-KSC2073H2TU
    Q2 2SC1318 KSC2383Y or KSC2690AY
    Q3 2SC1318 KSC2383Y or KSC2690AY
    Q4 2SB507 KSA940 512-KSA940TU
    Q5 2SA720 KSA1013
    Q6 2SD313 KSC2073 512-KSC2073H2TU

    Are there recommended power supply resistor replacements in a SX-939 restore???

    Reason I am asking is I think in the case of a SX-1010 Mattsd might have recommended replacing four. R11 and R12 are the +56/-56 feeds; R20 is the 13V feed and R21is the 35V feed. Cannot remember if this was Mattsd standard operating procedure or because in the particular thread the power supply was fried. Again these are resistor and voltage identifications in the SX-1010 and DO NOT reflect identifications of what would be corresponding in the SX-939.

    R11: 10 Ohm 1/4 watt: 660-MFS1/2DCT52R10R0 10 Ohm 1/2 watt
    R12: 10 Ohm 1/4 watt: 660-MFS1/2DCT52R10R0 10 Ohm 1/2 watt
    R20: 3.3 Ohm 1/4 watt: 660-MF1/2DCT52R3R32F 3.32 Ohm 1/2 watt
    R21: 10 Ohm 1/4 watt: 660-MFS1/2DCT52R10R0 10 Ohm 1/2 watt
     
    Last edited: May 28, 2018

     

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  2. larryderouin

    larryderouin Turn it UP, POP? PLLUUEEEZZZZZEE Subscriber

    Messages:
    21,829
    Location:
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    So far it looks ok at 1st glance. While you're in there, if the P.S. has burned or darkened areas pull one end of the resistors and check them for value. If within 5% they'll be ok, BUT!, I'd put in new ones raised OFF the board to get some air around them for heat dissipation and to help the board stay intact. Resistors are cheap, replacement boards aren't. Of the 939 P.S. boards I've seen, they tend to not be as bad as the 1010. So you might get off easy here. Mine runs literally 24/7 and barely gets warm. I've taken temps around the unit and the hottest is on the P.S. @ 123*F with the Heatsinks for the output's barely 90*F. Use the 1010 25mv spec for BIAS, as the PIONEER Engineers goofed on this one too.

    Caps;
    C15 & C16 take them up to 80v. UPM is a slightly larger case than a UPW, but same basic series. 10mm x 25mm vs. 10mm x 12.5mm on the UPW.
    https://www.mouser.com/ProductDetail/Nichicon/UPM1K101MPD?qs=/ha2pyFadugkhUTFiGYtT%2bAk2FEoMcXI2brDCmGY5Q1X14pRyQkvIg==

    C22 & 23 are UPW's.
    C22 & C23 Take them up to 25V.
    C22 https://www.mouser.com/ProductDetail/Nichicon/UPW1E222MHD?qs=sGAEpiMZZMtZ1n0r9vR22UXbiauPutPB/PZr%2bUXTLH4=

    C23 https://www.mouser.com/ProductDetail/Nichicon/UPW1E221MPD?qs=sGAEpiMZZMtZ1n0r9vR22UXbiauPutPBQ%2bp1FJOx3po=

    Other than that, looks good.
     
    Last edited: May 26, 2018
  3. Spenser

    Spenser AK Subscriber Subscriber

    Messages:
    402
    Location:
    Pittsburgh, PA, USA
    Thanks Larry. I appreciate your taking a look and offering suggestions. Here is a picture of the power supply board. You would think they would have given the resistors more room to breath. I don't see evidence of damage (on this side). I'm sure you've seen the soldered fuses before. Thanks again.

    Pioneer SX 939 Power Supply.jpg
     
    Last edited: May 28, 2018
  4. Spenser

    Spenser AK Subscriber Subscriber

    Messages:
    402
    Location:
    Pittsburgh, PA, USA
    I noticed xraytonyb recently posted a Pioneer SX 939 restoration YouTube video in case you might be interested.

    Enjoy!

     
  5. kevzep

    kevzep Its all about the Music Subscriber

    Yeah Tony is hilarious!! I like him, he does a good job, but boy he gets off topic, which is where all the interesting stuff is said....

    But it is worth a look, he goes through the tuner alignment and everything. I recommend watching his channel he does some interesting stuff.
     
  6. Spenser

    Spenser AK Subscriber Subscriber

    Messages:
    402
    Location:
    Pittsburgh, PA, USA
    Power Supply Parts List DRAFT 2

    See what you think.

    DRAFT 2 -- DO NOT USE -- LIST STILL UNDER DEVELOPMENT

    AWR-052-0 Power Supply

    AWR-052 C11 47uf 63v cea up it to 100V 647-UPW2A470MPD
    AWR-052 C12 47uf 50v cea up it to 100V 647-UPW2A470MPD
    AWR-052 C13 470uf 80v ach-038 up it to 100V 647-UPW2A471MHD
    AWR-052 C14 470uf 80v ach-038 up it to 100V 647-UPW2A471MHD
    AWR-052 C15 100uf 63v cea up it to 80V 647-UPM1K101MPD*
    AWR-052 C16 100uf 63v cea up it to 80V 647-UPM1K101MPD*
    AWR-052 C17 47uf 16v cea up it to 25V 647-UPW1E470MDD
    AWR-052 C18 47uf 16v cea up it to 25V 647-UPW1E470MDD
    AWR-052 C21 47uf 50v cea up it to 100V 647-UPW2A470MPD
    AWR-052 C22 2200uf 10v cea up it to 25V 647-UPW1E222MHD*
    AWR-052 C23 220uf 16v cea up it to 25V 647-UPW1E221MPD*
    AWR-052 C24 1000uf 35v ach-039 647-UPW1V102MHD

    Filter Caps

    C1 10000UF 50V 10000uF 63V 647-LKG1J103MKN*
    C2 10000UF 50V 10000uF 63V 647-LKG1J103MKN*

    Q1 2SD313 MJE3055T 512-MJE3055TTU*
    Q2 2SC1318 KSC2383Y 512-KSC2383YTA*
    Q3 2SC1318 KSC2383Y 512-KSC2383YTA*
    Q4 2SB507 MJE2955T 511-MJE2955T*
    Q5 2SA720 KSA916YTA 512-KSA916YTA*
    Q6 2SD313 MJE3055T 512-MJE3055TTU*

    R10 2.7K 1W 594-5073NW2K700JA100*
    R11 820Ohm 2W 588-42J820E*
    R11 820Ohm 2W 588-42J820E*

    *reflect edits to first draft power supply parts list

    -Draft reflects four capacitor changes on suggestion Larry D.

    -Some alternative transistor ideas I'm running up the flag pole derived from xraytonyb Pioneer SX-939 restoration YouTube video posted in February.

    -Changed to the Nichicon gold series filter capacitor. Looked at dimensions this vs. first draft selection Nichicon LKS series, and the Nichicon LKG presents a better, near-perfect diameter match to the originals. Snap on version would be almost half the price but snap ons are "on order" with Mouse; not due for delivery until August; and, you know how THAT goes. Have not checked availability / postage / net cost comparison other possible suppliers. Notice I dropped the capacitance back down to specified original. Kept the increased voltage rating of 63V. An aside here, xraytonyb took readings after rebuilding the power supply and observed that the filter capacitors were running right at or slighly above 50V. He said the original Nippons were probably underated at their specified 50V in the day.

    -Probably nothing wrong with the three power resistors but replacing in order to raise them off the board for better heat dissipation. Please check my selection of wire wounds for the two and metal film for the other.

    -Note I tried to save a couple bucks by getting the "Pioneer SX-939 Service Item" -- which is just the big schematic and foil sides -- from Stereo Manuals, but I'm seeing differences at least in the power supply. I will post an update if there are further departures as we go along. Rick Stout said the service item was in a collection of dozens Pioneer assembled together and distributed in a binder.
     
    Last edited: May 29, 2018

     

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  7. Spenser

    Spenser AK Subscriber Subscriber

    Messages:
    402
    Location:
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    Protection Relay

    I HAVE NOT TRIED THIS YET SO THE FOLLOWING IS AS YET UNVERIFIED BY ME.

    Here is a possible improvement on the relay LY2-DC24 . xraytonyb uses THESE (depicted in the video linked in Post #4 Part 1 at the 38:48 mark (38 min 48 sec)):

    1) 653-MY2-DC24 (MY2-DC24(S)) Omron Relay

    2) 16-782C1 Magnecraft Clip

    Several advantages.

    A) Instead of bridging two relay contacts per channel, you only use one per channel.

    B) The relay features a larger, heavier duty contact-pad.

    C) Eliminates an issue. If you have two contacts making the connection for one of the channels, one contact ALWAYS is going to engage before the other -- it is physically impossible to engineer it otherwise -- so one of the contacts will receiver more stress, therefore more wear than the other.

    D) The clip is a nifty mounting solution. One thing to be sure to do. Apply a dab of super glue or something between it and the relay housing for better hold.

    E)The MY2 relay is less expensive. My math says $9.64 for it and the clip vs. $17.82 for the LY2DC24 and 4 hexagonal standoffs 534-24315 (4)
     
    Last edited: May 30, 2018
  8. Spenser

    Spenser AK Subscriber Subscriber

    Messages:
    402
    Location:
    Pittsburgh, PA, USA
    Here is a first swipe at the Protection Circuit parts list. Please take a look.

    DRAFT 1 Protection Circuit Parts -- Do Not Use -- List Under Development

    AWM-062-0 Protection Circuit

    AWM-062 C1 .22uf 10v cssa up it to 63V 505-MKS2C032201BKI00
    AWM-062 C2 .22uf 10v cssa up it to 63V 505-MKS2C032201BKI00
    AWM-062 C3 330uf 6v cea up it to 10V 647-UPW1A331MPD
    AWM-062 C4 330uf 6v cea up it to 10V 647-UPW1A331MPD
    AWM-062 C5 4.7uf 25v cea up it to 35V 647-UPW1V4R7MDD
    AWM-062 C6 100uf 16v cea up it to 25V 647-UPW1E101MED

    Q1 2SC869 KSC1845 or 2N5551 512- KSC1845FTA
    Q2 2SC869 KSC1845 or 2N5551 512- KSC1845FTA
    Q3 2SC945 KSC1845 512- KSC1845FTA
    Q4 2SC945 KSC1845 512- KSC1845FTA
    Q5 2SA733 KSA992 512-KSA992FBU
    Q6 2SC945 KSC2383YTA or KSD1616A 512- KSC2383YTA
    Q7 2SC1384 KSC2690AYS or a TO-5 5W power transistor 512- KSC2690AYS

    Relay 653-LY2F-DC24 or MY2-DC24 653-MY2-DC24

    Hexagonal Standoffs to use w/ LY2F 534-24315 (4) –OR—
    Clip to use with w/ MY2 16-782C1 528-16-782C1

    Flyback Diode Modification 1N4004 or 1N4148 863-1N4004RLG

    Add 1N4004 flyback diode between pins 9 (anode +) and 10 (cathode -) i.e. banded side to 10 or mount across relay pins in equivalent confirguration.
     
    Last edited: May 30, 2018
  9. kevzep

    kevzep Its all about the Music Subscriber

    Yeah I saw this too and have done it on other receivers...Its actually quite a good idea.
     
  10. kevzep

    kevzep Its all about the Music Subscriber

    I use Nichicon Gold Tune or Superthrough, you can almost find the right dimensions as the original, although you have to be careful with availability.
    In the power supply I use those Nichicon PW, but in the rest of the receiver I use Nichicon Fine Gold and Muse...I think it brings good results...
     
    Oldsansui441 likes this.
  11. Awesomeaudio

    Awesomeaudio AK Subscriber Subscriber

    Messages:
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    Haha yeah ! I love his videos too. Great guy and full of knowledge.
    Even though he drifts off topic, the information is very good for newbies like myself and many others.
    I wonder if he's a member here ?
    Does anyone know ?
     

     

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  12. Spenser

    Spenser AK Subscriber Subscriber

    Messages:
    402
    Location:
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    Thanks for verification. You have applied the relay MY2-DC24(S) to good result. 653-MY2-DC24
     
  13. Spenser

    Spenser AK Subscriber Subscriber

    Messages:
    402
    Location:
    Pittsburgh, PA, USA
    Sorry let me go ahead and get the Power Amplifier up here, too. If someone could take a look at these. I know I've put a lot up here to go over between the Power Supply, Protection and Power Amplifier.

    Should C5, C6, C11, C12 all be bumped up in voltage and to what?

    Any opinions on whether there is any argument for replacing Q5 and Q6 while I have the board out? Of course I will do Q7 and Q8. All the other transistors in the Power Amplifier I plan to leave alone unless get it back together, test, and find an issue.

    Do the trimmers substitutions looks right?

    Draft 1 Power Amplifier Parts -- Do Not Use -- List Under Development

    AWH-030 Power Amplifier

    AWH-030 C1 .47uf 25v cssa 50V film 505-MKS2.47/50/10T
    AWH-030 C2 .47uf 25v cssa 50V film 505-MKS2.47/50/10T
    AWH-030 C3 1uf 25v cssa 50V film 505-MKS2B041001C00MF
    AWH-030 C4 1uf 25v cssa 50V film 505-MKS2B041001C00MF
    AWH-030 C5 33uf 16v cea 647-UPW1C330MDD
    AWH-030 C6 33uf 16v cea 647-UPW1C330MDD
    AWH-030 C11 330uf 10v cea 647-UPW1A331MPD
    AWH-030 C12 330uf 10v cea 647-UPW1A331MPD

    Q1-4 are 2SA763 NOT the originally specified 2SA726 so these stay.
    Q7 2sc1451 KSC3503 512-KSC3503DSTU
    Q8 2sc1451 KSC3503 512-KSC3503DSTU
    Q5 2SB527 2N6126 610-2N6126
    Q6 2SB527 2N6126 610-2N6126

    VR1 10K Bourns side crossed 25-turn 652-3296P-1-103LF
    VR2 10K Bourns side crossed 25-turn 652-3296P-1-103LF
    VR3 100 Bourns side crossed single-turn 652-3362S-1-101LF
    VR4 100 Bourns side crossed single-turn 652-3362S-1-101LF

    Thank you! I appreciate it. Could you share the choices you would make for example in the power amplifier board if you could take a moment? Thanks.

    Me, too. Been watching his stuff off and on for awhile. I think he works on medical imaging equipment for his day job. We have a distinct dialect and perhaps even attitudes here in Southwestern Pennsylvania, at one time the U.S. western frontier.
     
    Last edited: May 30, 2018
  14. Awesomeaudio

    Awesomeaudio AK Subscriber Subscriber

    Messages:
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    [/QUOTE]Me, too. Been watching his stuff off and on for awhile. I think he works on medical imaging equipment for his day job. We have a distinct dialect and perhaps even attitudes here in Southwestern Pennsylvania, at one time the U.S. western frontier.[/QUOTE]

    Yeah, I think it's X-ray machines to be specific hence his moniker xraytonyb.
    I have a lot of respect for the man. He's extremely knowledgeable.
    Just on a funny note...
    Don't you think he sounds like Shaggy from Scoobie Doo ?? ( and I mean the Original Scoobie Doo ).
    I tried putting my finger on it several times then it just came to me :D:D:D
     
  15. kevzep

    kevzep Its all about the Music Subscriber

    Ah, thats it!! I am going to watch this video again tonight.....!! He's a top bloke though, I like Tony.....He's just posted a new video, restoring an Ampeg guitar amp, quite interesting since I am a guitarist..
     
  16. kevzep

    kevzep Its all about the Music Subscriber

    I'm actually hopeless at documenting stuff, I'll look through my orders and see what I can find.....Often I just wing it, depends on the client and how much money he/she wants to spend....
     

     

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  17. Spenser

    Spenser AK Subscriber Subscriber

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    Oh my gosh. I think maybe so. Too funny.
     
  18. Spenser

    Spenser AK Subscriber Subscriber

    Messages:
    402
    Location:
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    Nah, don't do the extra work. I will think about it when I get to the other boards or a future machine. I appreciate your bringing these up. As we know there is long-standing debate.
     
  19. kevzep

    kevzep Its all about the Music Subscriber

    Yes I think its one of those things you just have to try, I saw that the WIMA film caps were on the Bom for the SX1010, I modified the bom to suit what I wanted for it, but thought I'd just give the films a go, and the good thing was, I had the SX1010 as the Lab music system for a few weeks, so I got to know it before the re-cap, so it was fresh in my mind when I completed it.
    I like to run my clients amps for a while after I have done big jobs to make sure they're good to go....I've had some nice amps to listen to!!
     
  20. Spenser

    Spenser AK Subscriber Subscriber

    Messages:
    402
    Location:
    Pittsburgh, PA, USA
    Can someone take a look at these power supply, power-resistor-substitution-picks and let me know if they look OK or suggest what would make great replacements?

    It's not that the old ones are bad. They are likely fine.

    I simply want to get these components elevated off and some air around them.

    Thanks man.
     

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