Sansui solid state 7000 repair, recap, and restore

Discussion in 'Exclusively Sansui' started by dlucy, Jan 28, 2018.

  1. dlucy

    dlucy dlucy67 (Doug) Subscriber

    Messages:
    1,728
    Location:
    Philadelphia, PA
    IMG_3820.jpg

    A fellow AK'er has a Sansui 7000 that he'd like to repair and restore, so I said "sure! that'll be fun!" After looking a little into the specs, parts and history of this big 70's receiver I found it is a high power cap-coupled design... so *I* had to buy one, too.

    So, now I've got two units to repair (both have the two output transistors in one channel dead), then recap, and, at least for mine, upgrade/mod to modern parts. This thread is just a record of the work.

    @DCinDC has compiled a master thread of some good info as well as written quite a few posts on his own. So, there is plenty to help with this. http://www.audiokarma.org/forums/index.php?threads/the-master-sansui-7000-thread-link-thread.443893/

    Once all the boards have been cataloged and compared to the schematic, and after a couple of orders of parts have been gathered and installed, I'll post a BOM for the results. Note: Both of the units I've got on the bench are the large-tone-board variants. If you're following along for your own unit, you'll need to determine which variant you have before using everything from this thread. http://www.audiokarma.org/forums/index.php?threads/sansui-7000-a-tale-of-two-bothers.369638/
     

     

    Please register to disable this ad.

  2. dlucy

    dlucy dlucy67 (Doug) Subscriber

    Messages:
    1,728
    Location:
    Philadelphia, PA
    Two gigantic electrolytic caps for output coupling, a driver board on a slot just to the right side of those caps and then a matching driver board on the opposite left side. Kinda neat how that board pops right out. The output transistors are accessed from the sides of the unit.

    Top side internal nudie shot:

    IMG_7105.JPG

    Underside internals nudie shot (with larger tone board):

    IMG_7114.JPG
     
    smurfer77, Hyperion and rimtap like this.
  3. dlucy

    dlucy dlucy67 (Doug) Subscriber

    Messages:
    1,728
    Location:
    Philadelphia, PA
    Kinda odd power protection board with a SCR that acts as the switch that shuts off output until you power-off then power-on.

    IMG_7126.JPG

    @DCinDC points out how easily you can bypass the SCR here: http://www.audiokarma.org/forums/index.php?threads/4-speakers-on-my-sansui-7000.360533/#post-5696137

    Sansui 7000 power protection board foil.png

    Sansui 7000 power protection board schematic.png

    Someone has subbed a ECG224 in for one of the 2SD223's. I'll be replacing everything on the board except the L010 coil.

    Order plan for Power Protection board:

    C010,C014,C015 3 Capacitor Ceramic 0.022 uF 50V ---> 667-ECQ-E2223KF3
    C011,C012,C017 3 Capacitor Electrolytic 220 uF 50V ---> 647-UPW1H221MPD6
    C017 1 Capacitor Electrolytic 220 uF 25V ---> 647-UPW1H221MPD6
    C901,C902 2 Capacitor Electrolytic 1 uF 50V ---> 647-UFW1H010MDD
    C903 1 Capacitor Ceramic 0.01 uF 50V ---> 667-ECQ-E2104KF
    VR901,VR902 2 Resistor Trimpot 5K - ---> 652-3352H-1-502LF
    TR010,TR011 2 Transistor BJT 2SD223 (O, Y, G) - ---> 512-KSC5603DTU
    TR901,TR902 2 Transistor BJT 2SC711 (E, F) - ---> KSC1845F
    TR903 1 Transistor BJT 2SA628 (E, F) - ---> KSA1015
    D010 1 Diode Zener ZBI-12 12V 1W ---> 78-1N4742A
    D011 1 Diode Zener ZBI-25 25V 1W ---> 863-1N5360BRLG
    D012 2 Diode Rectifier 10DC1 Dual common cathode ---> UF4004 Need two UF4004 for one 10DC1
    D901,D902 2 Diode Rectifier 1N60 - ---> 78-BAT41 Ok replacement in a PSU for 1N60
    SCR901 1 SCR - 2SF656 - ---> 821-MCR100-6A1G Reverse the pin order
    R010 1 Resistor Carbon 820 R 1/2W ---> 71-RN65D-F-825
    R011 1 Resistor Cement 390 R 3W ---> 71-CPF3-G-390-E3
    R012 1 Resistor Carbon 1K 1/2W ---> 71-RN65D-F-1.0K
    R013 1 Resistor Cement 270 R 2W ---> 71-CPF2-270
    R901-R904,R910-R912 7 Resistor Carbon 4.7K 1/4W ---> 71-RN60D4701F
    R905 1 Resistor Carbon 47K 1/4W ---> 71-RN60D4702FTR
    R906 1 Resistor Carbon 10K 1/4W ---> 71-RN60D-F-10K
    r907 1 Resistor Carbon 1K 1/4W ---> 71-RN60D-F-1.0K
    R908 1 Resistor Carbon 12K 1/4W ---> 71-RN60D1202F
    R909 1 Resistor Carbon 3.9K 1/4W ---> 71-RN60D-F-3.92K
    R backside 01 1 Resistor Carbon 560 R 1/4W ---> 71-RN60D5620F/R
     
    smurfer77, Hyperion and rimtap like this.
  4. dlucy

    dlucy dlucy67 (Doug) Subscriber

    Messages:
    1,728
    Location:
    Philadelphia, PA
    There is a separate driver board for each channel and these boards plug into a slot. Makes it easy to pull them.

    IMG_7108.JPG

    Sansui 7000 driver board foil.png

    Sansui 7000 driver board schematic.png


    Order plan for driver boards (two of them):

    TR801 2 Transistor BJT 2sc711 (E or F) TO-92 ---> KSC945CG C for ECB pinout and G hFE gain of 300 or so
    TR802 2 Transistor BJT 2sc871R (F) TO-92 ---> KSC1845F
    TR803 2 Transistor BJT 2sc627 (3) TO-39 ---> ZTX696 plus TO-92 heatsink
    TR803-heatsink 2 ---> 532-575200B00 TO-92 heatsink for ZTX696
    TR804 2 Transistor BJT 2SC984 C TO-1 ---> KSC2690A (I used the 2690A for it's larger TO-126 package) or KSC2383 (smaller [so lower dissipation] TO-92L package)
    TR805 2 Transistor BJT 2SC680 (B) TO-66 ---> MJE15032G have to bend TO-220 legs
    TR806 2 Transistor BJT 2SA566 (B) TO-66 ---> MJE15033Ghave to bend TO-220 legs
    VR801 2 Resistor Trimpot 100K - ---> 652-3352H-1-104LF
    VR802 2 Resistor Trimpot 1K - ---> 652-3352H-1-102LF
    C801 2 Capacitor Film 0.33 uF 50V ---> 667-ECQ-E2334KF
    C803,C808 4 Capacitor Ceramic 100 pF 50V ---> 81-RDE5C2A101J0M1H3A
    C802 2 Capacitor Electrolytic 100 uF 25V ---> 647-UKL1V101MPDANATD (service manual said 10V, but on board was a 25V)
    C804 2 Capacitor Electrolytic 220 uF 10V ---> 647-UKL1V221KPD
    C805 2 Capacitor Electrolytic 4.7 uF 50V ---> 647-UKL1H4R7MDDANA
    C806 2 Capacitor Electrolytic 3.3 uF 25V ---> 647-UKL1H3R3MDD1TA
    C807 2 Capacitor Electrolytic 100 uF 50V ---> 647-UKL1H101MPD
    C809 2 Capacitor Electrolytic 470 uF 6V ---> 647-UKL1V471KHD
    C810 2 Capacitor Film 0.1 uF 50V ---> 667-ECQ-E2104KF
    C813,C814 2 Capacitor Electrolytic 0.1 uF 250V ---> 647-UVY2D0R1MED
    R823 2 Resistor Cement 4.7 R 2W ---> 71-CPF2-F-4.7
    R812 2 Resistor Carbon 680 R 1/2W ---> 71-RN65D-F-681
    R816 2 Resistor Carbon 6.8K 1/2W ---> 71-RN70C-F-6.81K
    R818,R820 4 Resistor Carbon 220 R 1/2W ---> 71-RN65D-F-221
    R819 2 Resistor Carbon 10 R 1/2W ---> 71-RN65D10R0F/R
    R821,R822 4 Resistor Carbon 6.8 R 1/2W ---> 594-5073NW6R800J
    R801 2 Resistor Carbon 10K 1/4W ---> 71-RN60D1002F/R
    R802 2 Resistor Carbon 470K 1/4W ---> 71-RN60D4703FTR
    R803 2 Resistor Carbon 270K 1/4W ---> 71-RN60D2743FTR
    R804 2 Resistor Carbon 560K 1/4W ---> 71-RN60D-F-562K
    R805 2 Resistor Carbon 100 R 1/4W ---> 71-RN60D-F-100
    R806 2 Resistor Carbon 2.2K 1/4W ---> 71-RN60D2201F/R
    R807 2 Resistor Carbon 3.9K 1/4W ---> 71-RN60D-F-3.92K
    R808 2 Resistor Carbon 33K 1/4W ---> 71-RN60D3302FTR
    R809,R815 4 Resistor Carbon 3.3K 1/4W ---> 71-RN60D-F-3.32K
    R810 2 Resistor Carbon 10K 1/4W ---> 71-RN60D1002F/R
    R811 2 Resistor Carbon 100K 1/4W ---> 71-RN60D-F-100K
    R813 2 Resistor Carbon 220 R 1/4W ---> 71-RN60D-F-221
    R814 2 Resistor Carbon 1.5K 1/4W ---> 71-RN60D-F-1.5K
    R817 2 Resistor Carbon 39 R 1/4W ---> 71-RN65D-F-39.2
     
    Last edited: Feb 17, 2018
  5. Hipocrates

    Hipocrates Anti-Muppet Subscriber

    Messages:
    1,578
    Location:
    Costa Rica
    :lurk:
     
    dlucy likes this.
  6. dlucy

    dlucy dlucy67 (Doug) Subscriber

    Messages:
    1,728
    Location:
    Philadelphia, PA
    First half of the restoration parts arrived, I'll be desoldering and then installing modern equivalents all weeknd. Fun! IMG_7385.JPG
     
    smurfer77, rimtap and Hipocrates like this.

     

    Please register to disable this ad.

  7. Wolverine

    Wolverine AK Subscriber Subscriber

    Messages:
    5,429
    Location:
    VA Beach Virginia
    Very cool post that I will be following with great interest...:) Do you need me to send you a down payment for your efforts at this point?
     
  8. dlucy

    dlucy dlucy67 (Doug) Subscriber

    Messages:
    1,728
    Location:
    Philadelphia, PA
    Hah! No, no need. Thanks, though.

    Let me work out the right replacements in the 7000 I bought for myself, then I'll do a better job on your 7000.

    Replacing the components isn't so bad in this model. I wonder how the innards, boards and connecting wires compare to the Eight and the Eight Deluxe.

    The "power protection" board in this 7000, though, has a buttload of connecting wires soldered to the underside of the board instead of to an edge connector or posts. THAT is gonna be a pain. One very redeeming use case for today's camera-included smartphones.

    IMG_7140.JPG
     
    smurfer77, Fredrik 1977 and Hyperion like this.
  9. dlucy

    dlucy dlucy67 (Doug) Subscriber

    Messages:
    1,728
    Location:
    Philadelphia, PA
    Last edited: Mar 1, 2018
    smurfer77, JoseHH, Overundr1 and 3 others like this.
  10. dlucy

    dlucy dlucy67 (Doug) Subscriber

    Messages:
    1,728
    Location:
    Philadelphia, PA
    This also turned out to be a good example, for me, of how the "modern" TO-220 transistor package was designed to be a drop-in replacement for the "old" TO-66 transistor package. It fit perfectly, the pinouts matched, the TO-66 case and TO-220 backplate were the collector and mechanically & electrically connected. Almost like it was designed to be like this. ;)
     
    americannigh likes this.
  11. EngineerNate

    EngineerNate AK Subscriber Subscriber

    Messages:
    2,170
    Vishay/Dale metal films? Nice! Are you replacing all of the resistors just as a precaution or did some let the smoke out and you want them all to match?
     
    dlucy likes this.

     

    Please register to disable this ad.

  12. Wolverine

    Wolverine AK Subscriber Subscriber

    Messages:
    5,429
    Location:
    VA Beach Virginia
    Wow that is a nest of wires!
    Good luck!!

    Hope all is well!!
     
  13. dlucy

    dlucy dlucy67 (Doug) Subscriber

    Messages:
    1,728
    Location:
    Philadelphia, PA
    Great question. I'll do my best to give you a good answer.

    I'm no E.E. and have limited electronics-diagnosing abilities. So, I mostly shotgun replace stuff that I think is questionable. Mostly.

    When I replace resistors, I try to replace with metal film. Someone somewhere said they are lower noise.

    During this particular driver board restore, when I measured the resistors coming off the board (these are originals) there were maybe 25% that had significant drift or just poor tolerance examples. And this is the output transistor driver board, so some of these resistors get pushed hard. So, I replace 'em. It's like a few bucks, total, to replace all the resistors on the board, have higher precision, longer life, and (often) higher wattage.

    And I use a lead former tool to move the 1/2 watt and higher resistors up off the PCB so they get more air circulation / room to dissipate heat.

    IMG_7445.jpg

    And I like the Vishay RN series clearly-printed values. I know how to read normal resistor color bands, but it's a pain and often 30 years have blurred the difference or perception of blue to green or purple. So, I like the RN series and their "2210F" designation. Easy for me to read. And when I use the lead bending tool to prep the RN series to go on the board, I make sure the value printing is facing up. Towards the next poor guy, 30 years from now, when he's trying to repair my work.

    IMG_7436.jpg
     
    Last edited: Feb 17, 2018
    smurfer77, Hyperion and EngineerNate like this.
  14. dlucy

    dlucy dlucy67 (Doug) Subscriber

    Messages:
    1,728
    Location:
    Philadelphia, PA
    The Vishay CPF series is what I use when replacing the flameproof or cement-encased power resistors. It looks crazy, but they are just as good at flameproofing as the older ones and they are metal film. Just... so... tiny-looking....
     
    Hipocrates and EngineerNate like this.
  15. EngineerNate

    EngineerNate AK Subscriber Subscriber

    Messages:
    2,170
    I made the mistake of putting the label down on some Vishay resistors on a headphone amp I built. Won't make that mistake again.

    If I do a full resistor replacement or a new build, I too like the Dale milspecs. If I do a partial replacement I match the resistor type already in the board (carbon film vs metal film) to avoid changing the sonic signature in unpredictable ways by mixing things up.
     
    dlucy likes this.
  16. Hipocrates

    Hipocrates Anti-Muppet Subscriber

    Messages:
    1,578
    Location:
    Costa Rica
    Man those renew boards looks awesome! Great work!
     
    Last edited: Feb 17, 2018
    Hyperion, rimtap and dlucy like this.

     

    Please register to disable this ad.

  17. Overundr1

    Overundr1 AK Subscriber Subscriber

    Messages:
    2,478
    Location:
    Mississippi
    Interesting TO-66 to TO-220 post. Have no idea why I never noticed that correlation before, worth the whole thread which is excellent btw sir :)
    :lurk:
     
    dlucy and Hyperion like this.
  18. dlucy

    dlucy dlucy67 (Doug) Subscriber

    Messages:
    1,728
    Location:
    Philadelphia, PA
    Thanks!

    This will be the first time I've actually used the idea. There are many posts here to other threads using this example. It's usually "I'm having a hard time finding a 2N3333 (whatever), help!" and the replies are "That's in a TO-66 metal can and no one makes them any more. You'll have to switch to modern production TO-220 devices which should drop right in and attach to the heatsink where the TO-66 can was screwed down."
     
  19. ouimetnick

    ouimetnick Hafler Fan!

    Messages:
    975
    What lead forming tool did you use to get those factory looking kinks in the resistor legs?
     
    Motnick likes this.
  20. dlucy

    dlucy dlucy67 (Doug) Subscriber

    Messages:
    1,728
    Location:
    Philadelphia, PA
    Great question! Something I learned from listening in here on AK. It's a Lead-forming tool. I bought this one: Xuron 573L Xuro-Former Lead Former https://www.amazon.com/dp/B000IBQEZQ?ref=yo_pop_ma_swf

    It's an odd-looking thing, but it works well.

    IMG_7749.JPG IMG_7750.JPG IMG_7751.JPG
     

Share This Page