Another SX-1010 this time a transformer

Discussion in 'Pioneer Audio' started by Bradbrews, Apr 5, 2017.

  1. Oldsansui441

    Oldsansui441 AK Subscriber Subscriber

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    KSA992 FBTA are the same gain as the FBU just come in cut tape not bulk.

    KSA1220AYS is fine and is the highest gain version for this part.
    .
    You may have to get the KSC1845's form Digikey or Element 14.

    The datasheets for each will tell you their gain values etc.

    I usually always use these fairchild transistors but when l have ran out etc l have substituted for BC's etc but the KSA992's and KSC1845's have better gains and have better leg orientation, usually you just have to reverse them to the originals.
     
  2. Bradbrews

    Bradbrews New Member

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    Finished the rebuild of the left channel amp, and started on the right.
    I checked every transistor as I pulled them, and didn't find any that had failed. I can only check C1 with my Fluke, and on both channels, the ones I pulled out read high, 0.98 uF and 0.87 uF vs. the 0.68 uF the new ones both read and were supposed to be.
    Since the right channel did not have any failed outputs, I hope that it is less stressed than the left, that had 3 failed.
    The physical replacement process is going about as well as I could have hoped for, given that this is a first time project of this scope.
    Now if I just got each one of those BCE leads in the correct spots..
    I also ordered parts to rebuild the power supply and protection circuits. If I get it going after the amp board rebuilds I hope to progress to those!
     
  3. Oldsansui441

    Oldsansui441 AK Subscriber Subscriber

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    Sounds like you are progressing well, in regard to transistor leg placement just cast your eye over them all 2 or 3 times even after installing them just to make sure before you power it up again. Atleast with the Pioneer stuff the silkscreening on the board gives you a good point of reference.
     
  4. larryderouin

    larryderouin Do I get Food, Med's, or more gear this Month? Subscriber

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    type in ksc1845 without any suffix. There are 62998 in stock on the FTA.
    Not a problem with suffix's. The 1st is gain. the other 2 or 3 are packaging type. also download the data sheets for all transistors ordered to gain the pinout's. Most will be different from the originals.
    Pioneer used an insulating spray on the output tr's rather than a MICA insulator. Best get 8 new mica TO-3 Insulators 534-4636
    http://www.mouser.com/ProductDetail/Keystone-Electronics/4636/?qs=sGAEpiMZZMsQtlBhqKq43cDG0TrwBSwA
     
  5. Bradbrews

    Bradbrews New Member

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    I received all the transistors I need to redo the amp boards. I also got mica insulators. There are a couple on back-order for the power supply, but I'm not ready for them anyway.
    I have been using the diode test function of the Fluke 87, and per the manual it sends a test current through the diode, and reads out the voltage developed. Typically I get readings between 0.4 V and 0.6 V in the fwd direction and OL the other way. I pulled the STV-3 diodes (not the STV-3H's) and when I checked them they showed 1.44 V. I was getting ready to replace them with u4004's, but those read the more typical 0.6 V or so. Thinking that did not seem right, I went back and read this quote from MTF "It COULD also have stv-3 diodes at D7 and D8, which ARE LEFT IN PLACE if OK." So I put them back in.. Lots of details to pay attention too here.
     
  6. Oldsansui441

    Oldsansui441 AK Subscriber Subscriber

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    Yes this is correct.

    This is a correct reading also as the stv-3 will give a reading very similar to three diodes in series.
     
  7. Bradbrews

    Bradbrews New Member

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    Here is a picture of the completed left channel.
    IMG_3044.JPG
     
  8. Bradbrews

    Bradbrews New Member

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    Location:
    Near Ann Arbor MI
    Finished the rebuild of the right channel. It was good to have another board to compare the transistor orientation too.
    At least now both are the same, so either they are both correct, or both wrong!
    I wish that I had known to order new mica for Q9, and Q10 the transistors on the black heat sink on each amp board.
    I reused the old mica after cleaning it off, but it did have minor dents from the old units.
    Next up is putting the outputs back in, and seeing if I can get the STV-3H diodes remounted without issue.
    Then on to some re-reading of old threads on setting the pots and tickling the Dragon! DBT hooked up first of course.
    Right channel rebuilt.jpg
     
  9. Bradbrews

    Bradbrews New Member

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    :beerchug: Tonight I tickled the Dragon, and all went well. The light started out bright, and then dimmed as hoped on the DBT. I was able to adjust the pots and get the desired results. Gaining confidence I went to line voltage. I was able to set the idle to ~ 25 mv on both channels, and get sound out of the amp for the first time this century!
    This is by far the most complex repair I've ever done, and having a successful outcome is a big confidence booster.
    I think I will rebuild the power supply board now that I have a working unit, and I bought the parts when I placed the amp board order.
    So to summarize, this unit had a blown transformer, and 3 of the output transistors on the left channel. It did not seem to have any other outright failed components that I've found so far. Without the detailed descriptions that all of you have given in the many threads here on everything related to this whole process I would have had no idea how to have started this repair, much less successfully completed it. :thumbsup:
     
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  10. Oldsansui441

    Oldsansui441 AK Subscriber Subscriber

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    That is great news, bet you are very happy with the outcome. Good idea on doing the power supply :thumbsup:.
     
  11. loweran

    loweran AK Subscriber Subscriber

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    Good work! Now you should do the power supply, the protect board, put fresh caps in all boards, and replace the known suspect faulty transistors. In my case, I just went ahead and put all new transistors in since I had the boards out for the work already.

    The 1010 will reward you when you are done.
     
  12. Bradbrews

    Bradbrews New Member

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    Location:
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    Thanks, I have caps and some transistors for the power supply and protection board. I ordered those when I ordered the parts for rebuilding the amp boards.
    Are there other boards that have known suspects that I should do as well?
    Right now I have all new outputs, and new silicon and caps on the amp boards. I used the latest list of parts from AK that I could find. The transistors on the power supply board heat sink are on back order, so I'll probably rebuild the power supply without replacing them, at least for a while, but everything else on the standard list I have.
    The parts are scheduled for the end of the month to September...
     
  13. Bradbrews

    Bradbrews New Member

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    33
    Location:
    Near Ann Arbor MI
    I rebuilt the Power supply board this weekend. All except Q1, Q4, and Q7 which I don't have yet.. This board gave me the most trouble so far. The glue on the big caps was the root of my problems. When I was removing the old caps, I succeeded in lifting a trace off of the board, and cracking it! :( That glue sure makes old part removal difficult. I did get a solder joint over the cracked trace, but that did not seem like the best idea, so I laid a lead from the cap over to the next solder pad and made a bridge circuit in parallel with the original. Not pretty, but I think it will do fine.
    Lifted pad on cap.jpg IMG_3065.JPG
    I then went on to the Protection board. There I found a shorted Q1, and both C1, and C2 measured high, over 0.7 uF. The rebuild of that board went smoothly.
    I added the fly back diode between pins 9 & 10 as mentioned here in other threads.
    IMG_3076.JPG Protection board.jpg
    Up next is the Deoxit treatment.
    Are there other boards that really should be rebuilt or re-caped while I am in here?
    I may have to look elsewhere for the missing power supply transistors. If I don't get them soon I will be tempted to put the 1010 into service, and then who knows when I will open it back up.
     
  14. larryderouin

    larryderouin Do I get Food, Med's, or more gear this Month? Subscriber

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    Replace ALL 2sa725 or 2sa726's on any board that has them. Also 2sc1312,1313, and 1384's. 2sd313's get replaced.

    If the boards have 2sa763's in them vs. the 2sa726 or 725's, leave the 763's in. They are NOT problem children.

    Between Either MarktheFixer's list (which 95% of all lists on the pioneer forum are produced from)Zebulon1's or MATTSD's lists and the Service manual you can determine which transistors are problematic.

    All boards with the exception of the Tuner board should be rebuilt/totally recapped with problem transistors replaced. If the tuner is working as designed, I'd leave it be. Too many chances to knock it out of alignment by replacing the wrong cap and or transistor.
     
  15. Bradbrews

    Bradbrews New Member

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    Finally building the project lists for the remaining boards, Muting, Equalizer, and Control amp. The control amp BOM lists: C15 & C16 as Panasonic caps, while C23 & C24 are Nichicon caps. I suspect this is for a reason and I should put them where called for.
    My question is why are different ones used in each location?

    AWG-027-0: C15: 4.7uF 50v CEA: 667-EEU-FC1H4R7 4.7uF 50v
    AWG-027-0: C16: 4.7uF 50v CEA: 667-EEU-FC1H4R7 4.7uF 50v
    AWG-027-0: C23: 4.7uF 25v CEANL: 647-UKL1H4R7KDDANA 4.7uF 50v
    AWG-027-0: C24: 4.7uF 25v CEANL: 647-UKL1H4R7KDDANA 4.7uF 50v
     
  16. Oldsansui441

    Oldsansui441 AK Subscriber Subscriber

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    Hi, they are different because the CEANL (and CSSA) capacitors listed in the service manual were low leakage caps from factory. The Nichicon UKL's are a low leakage cap that replaces these, the CEA's can be replaced with any cap of your choosing ie the Panasonics.
     
  17. Bradbrews

    Bradbrews New Member

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    So that means that I could just put the Nichicon's in all 4 locations and not worry about it, other than the 8 cents more, right?
     
  18. markthefixer

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

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    It would be far easier for me if I didn't have to keep track of where each specific cap AND TRANSISTOR goes:
    because they perform different functions with different requirements.
     
  19. Bradbrews

    Bradbrews New Member

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    I get it. I've been doing well following the BOM exactly so far, and I won't start to deviate from it now. I was just trying to learn a little more.
     
  20. Bradbrews

    Bradbrews New Member

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    Location:
    Near Ann Arbor MI
    Two Steps forward, one step back.
    Well, the weather turned cold, and I'm back to rebuilding the 1010.
    I completed the EQ board, and made a rookie mistake. I only brought in one small speaker for testing, and hooked it up to the right channel. After the rebuild of the EQ, I checked it out with the DBT, and all was well, sound from FM on the speaker!
    I never checked the left channel. I went on to the control amp, and rebuilt it as well.
    Then I checked the right channel again - still works! Happy, and moving on to the fuse lights and switches, I thought what about the left channel?
    Well, sure enough, it doesn't work anymore. It worked after I rebuilt the amp boards, but when did I loose it?
    I spotted that the transistor circled here Q5 was in wrong.
    eq board.jpg
    I pulled the transistor, checked it -still OK- and put it in correctly.
    Still no sound on the left channel.
    So, I suspect that this mistake has blown something I already replaced.
    What steps should I go through now to find out what I did?

    Here is the control board just for reference;
    I double checked it and think its OK.
    IMG_3788.JPG
    Brad
     

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