1. Time for some upgrades in server hardware and software to enhance security and take AK to the next level. Please contribute what you can to sales@audiokarma.org at PayPal.com - Thanks from the AK Team
    Dismiss Notice

New Pioneer day! aka. another SX-1010 restoration

Discussion in 'Pioneer Audio' started by darkhosis, Jun 10, 2018.

  1. darkhosis

    darkhosis Active Member

    Messages:
    468
    Location:
    Seattle, WA
    Ever since my $40 SX-780 went as a gift to a friend for mixing work he did for me, I've been yearning for a Pioneer receiver. My Sansui 5000A is a strong capable machine but it doesn't quite work as well with my KLH Model Fives as a daily driver. Something about the bass, I prefer the Pioneer design - at least in my living room .

    Drove home with this 1010 last night bought from another hifi guy who was purging. Thanks to people here on the board, I knew that I should expect to put some work into this 1974 TOTL. It's been 2 years since my first failed attempt at fixing a 636...redemption time: got proper tools, enrolled at the local community college electronic program, and (hopefully) wisdom from some experience.

    Initial report:
    [​IMG]
    Cosmetically pleasant, one of the tone pot shafts is bent slightly but I can fix that with a needle nose pliers and slow patience.
    First step will be to remove as much of the dust inside as possible. I use a paint brush, toothbrush, vacuum and compressed air. I've been recapping music gear both modern and vintage, and these boards seem a tad brittle in comparison. Anything to watch out for?

    Main power caps measure: +55.8/-55.9 V DC

    test point 19 : L, -30 mV DC // R, 17 mV DC

    test point 14+16 : -17 mV DC // -11 mV DC

    DC offset : L, -31.3 mV DC (unstable) // R, 19.3 mV DC



    It's been serviced and I can tell the L amp board (near the transformer?) has been moved but I can't see what's been worked on.
    [​IMG]

    R amp board:
    [​IMG]

    It looks like heat damage to the board underneath those red resistors (?) but it's plain as day on the power supply board:
    [​IMG]

    At the seller's house the receiver started making intermittent crackling (once every 2-3 minutes) in the L channel after running for about 10-15 minutes. Could this be the source?

    Nothing else was visually standing out. The next step towards getting this into my living room and audio heaven is a parts order. Hoping the eagle eyes in this forum might catch a thing or 2 Im missing?

    Happy Sunday!
     

     

    Please register to disable this ad.

  2. rickb119

    rickb119 AK Subscriber Subscriber

    Messages:
    252
    Congrats on getting a mighty fine receiver! :beerchug: (I've had mine a week and am still in awe. :D )
     
    darkhosis likes this.
  3. kevzep

    kevzep Its all about the Music Subscriber

    I've recently restored one of these for a customer, but with a strange turn of events, I ended up buying it off him!!
    You really want to use the BOM list here on the forum which I used, and go through the whole thing, there are a bunch of dodgy transistors and such in these amps.
    So its a full re-cap, replace a bunch of transistors, some resistors.....Clean all the controls, dial in the Bias etc etc and you're good to go...get some new lamps as well....
    It will keep you busy for a few days.

    There will be a couple if guys here chime in, zebulon is a 1010 expert, and mattsd is another member which has some great insight into these units...
     
    Last edited: Jun 10, 2018
  4. kevzep

    kevzep Its all about the Music Subscriber

    When you do that toasty regulator board there, the one in the bottom of the amp, you might want to fit some extra heat sinks to dissipate more heat from those poor stressed Pass Transistors, this is what I did, you can also use adhesive ones too....I just had those ones on hand so I drilled a couple of holes and mounted them...Pretty easy...
    IMG_6194.JPG
     
    darkhosis likes this.
  5. kevzep

    kevzep Its all about the Music Subscriber

    Oh and don't forget to fit the playback diode to the Relay, for some reason Pioneer never did this, and as a result it stresses out the relay driver transistor...eventually they fail..

    here's a few pics of mine after the restore..
    I really like it, she's a nice punchy sound.....and has a nice elegant look, beautiful wood veneer...
    IMG_6175.JPG IMG_6181.JPG IMG_6176.JPG
     
    darkhosis likes this.
  6. darkhosis

    darkhosis Active Member

    Messages:
    468
    Location:
    Seattle, WA
    Thanks guys, it's real hard not getting to set it up and play it but I don't want to tempt fate.

    .. yeah, I will do the BOM as soon as I find it. The threads on here have been invaluable, after my experience with the 636 Im going to be extra careful working with the boards this time. I saw your heatsink mod, I have to admit Im not really experienced with installing them so I may be back with questions.

    ps. - nice 1010, I just realised from your pics that the eq knobs on mine are installed wrong.
     

     

    Please register to disable this ad.

  7. darkhosis

    darkhosis Active Member

    Messages:
    468
    Location:
    Seattle, WA
    PPS - If anyone can figure out the replaced component, that'd be cool. It was repaired by John Ledbetter at NW Audio who is more than qualified to work on this but the seller wasn't able to give me a receipt or anything more specific than "He replaced one thing and it started working again"
     
  8. zebulon1

    zebulon1 Building a new bench. Finally! Subscriber

    Messages:
    4,904
    Location:
    Las Vegas Nevada
    The board images you posted look original.
    It may of needed a service, amp adjustments. I couldn't see all the PS regulators on the "L" shape heatsink.
    A description of the issue that made it shop visit would be helpful.
     
    darkhosis likes this.
  9. darkhosis

    darkhosis Active Member

    Messages:
    468
    Location:
    Seattle, WA
    Sorry, Zeb, there wasn't much to go on since he isn't that technically-minded. He said that John spent some time trying to figure out the issue and ended up replacing a part that was pointed out. It was a couple years back. There was some scotch tape on the under side that had notation indicating something that looked like where the leads connected to the top side. I don't have a work bench so it's put away for the evening, I'll try to get some more pics later on
     
  10. kevzep

    kevzep Its all about the Music Subscriber

    Just sweep through it with the restoration, any typical issues with these units are taken care of in the resto. There are a lot of transistors replaced etc etc...
    That regulated board is rebuilt with new transistors caps and some resistors.
    If you sweep through with Mattsd parts list, it will cure most all problems.

    I can see there may have been a small transistor on one of the driver boars replaced perhaps, but not entirely sure....
     
    darkhosis likes this.
  11. darkhosis

    darkhosis Active Member

    Messages:
    468
    Location:
    Seattle, WA
    Can you guys help, I don't have a whole lot of experience ordering things using a BOM. It seems too easy??

    I cut and pasted what, I assume, is the most current BOM list from a post called Ultimate SX1010 by Zeb under the thread "SX-1010 project" Sept 2017 into the Mouser BOM tool.

    Does this sound right: Im looking at 38 different parts of varying quantities. $55 +s/h Then I still need to order the big caps, available via Digikey.

    Also, I was admonished by another guy who works on Pioneers to match transistors. What's the consensus on this..?

     

     

    Please register to disable this ad.

  12. larryderouin

    larryderouin Turn it UP, POP? PLLUUEEEZZZZZEE Subscriber

    Messages:
    21,894
    Location:
    Glen Burnie Md.
    The only one's you need to match are Q1 & Q2 on the amps. KSA992's to replace the 2sa726's. Price sounds about right as does parts count.
     
    darkhosis likes this.
  13. kevzep

    kevzep Its all about the Music Subscriber

    For the Main Caps, I used a pair of 22,000µF Nichicon Gold Tunes, they are the right diameter and length, fit like a glove...I feel its improved the bass, if that is even possible with the SX1010....better sustain and more punch, doesn't run out of steam at higher levels so much.

    Not cheap though, if it was a clients amp I'd consult before going ahead as there are cheaper options available...
     
  14. darkhosis

    darkhosis Active Member

    Messages:
    468
    Location:
    Seattle, WA
    Thanks guys. I ended up adding another 20 of the KSA992, I got a great deal on the receiver but I think I'll pass on the LGK Gold Tunes - they look nice tho.

    What's the story on those sleeves I see on the resistors on power supplies, I take it theyre for heat shielding. Is there a way to buy it smaller quantities?
     
  15. fernarias

    fernarias Super Member

    Messages:
    1,103
    Location:
    Merced, CA
    It's call this "Heat-Treated Fiberglass Sleeving".
     
  16. larryderouin

    larryderouin Turn it UP, POP? PLLUUEEEZZZZZEE Subscriber

    Messages:
    21,894
    Location:
    Glen Burnie Md.
    And it can be Re-Used on the new resistors. Unless you absolutely have to have new sleeving.
     
    darkhosis likes this.

     

    Please register to disable this ad.

  17. darkhosis

    darkhosis Active Member

    Messages:
    468
    Location:
    Seattle, WA
    I saw some other rebuilds of the PS where they had added sleeves to the resistors. I guess my question is how extensive should I mod the board to help prevent more heat damage.
     
  18. larryderouin

    larryderouin Turn it UP, POP? PLLUUEEEZZZZZEE Subscriber

    Messages:
    21,894
    Location:
    Glen Burnie Md.
    On the 1/4 and 1/2W resistors not needed. The 2W and 3W resistors should have some on them. With the P.S. inverted heat will rise into the board, so the more you can dissipate the heat from the larger resistors the better. 1/4" to 1/2" off the board will usually minimize further heat damage from the larger resistors. After 44 years it's pretty well cooked WELL DONE, so anything you do to keep it from cremation is good!
     
    merlynski and darkhosis like this.
  19. darkhosis

    darkhosis Active Member

    Messages:
    468
    Location:
    Seattle, WA
    Took another look at this today and did some measurements since I forgot my allen wrench key set (couldn't take off the tuning knob) and couldn't start on cleaning out knobs.

    For the first time, I've got a situation where nothing is really wrong to begin with. The Power Amp was way out of alignment but I managed to get it pretty close to spec, the left channel is fluctuating/tempermental.

    The one reading I get that is really out of 5% from the service manual is the Power Supply Circuit (AWR-054 ver O)
    pin / service man / reading
    15 / 56V / 60V
    14 / 24V / 28.4V
     
  20. darkhosis

    darkhosis Active Member

    Messages:
    468
    Location:
    Seattle, WA
    Started on the control amp board today. Does anyone have an opinion on replacing all transistors vs none vs "bad reputation" transistors in the control amp? I replaced the pair of 2SA725's but am reconsidering replacing the six 2SC1313
    IMG_7286.jpg
     

Share This Page