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:
    1,539
    Location:
    Philadelphia, PA
    The tuning dial lamps and function indicator lamps are in an unusual... place. Or, unusual to get to, actually.

    There is a two-sided metal cover over top of the wires leading to the function indicator lamps. You can remove that cover by three screws exposed via holes in that same cover.

    There is a single electrolytic cap sticking out from underneath this cover... and once you remove the cover you find there is a diode and two resistors under that cover. Sheesh. Why?

    Lamps 01 IMG_7965.JPG

    Lamps 02 IMG_7964.JPG

    Lamps 03 IMG_7966.JPG

    Lamps 04 IMG_7967.JPG

    Lamps 05 IMG_7970.JPG

    Lamps 06 IMG_7971.JPG

    Lamps 07 IMG_7988.JPG

    Lamps 08 IMG_7989.JPG

    Lamps 09 IMG_7992 2.jpg

    The fuse style tuning dial lamps get replaced with 8V LED warm white LED modules.

    The wheat bulb lamps for the function indicators and the meter lamps will need to be replaced with T1 3/4 size 6V AC wheat bulbs. There ins't enough remove to add diodes and caps to run LEDs.
     
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  2. dlucy

    dlucy dlucy67 (Doug) Subscriber

    Messages:
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    The meter lamps are also T1 3/4 AC wheat bulbs. They are held in by a two-piece metal frame.

    Meters lamps 01 IMG_7975.JPG
    Meters lamps 02 IMG_7978 2.jpg
    Meters lamps 03 IMG_7980 2.jpg
     
  3. 59volvo

    59volvo Well-Known Member

    Messages:
    957
    will be curious to hear your thoughts on how it sounds when all done. I wonder if it sounds more like a 2000/4000/5000 or seven/eight/eight delux
     
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  4. stereoguy70

    stereoguy70 AK Subscriber Subscriber

    Messages:
    554
    Location:
    Salem, NH USA
    You will probably find this out on your own after you plug it in set like that....but you will end up with excessive distortion due to being under voltaged. The jumper is supposed to be set to 117v for the US market. Your line voltage may be "120" but its usually closer to 117-118v and is not an issue for these.
     
  5. dlucy

    dlucy dlucy67 (Doug) Subscriber

    Messages:
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    Location:
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    The very first test of the unit will be the power supply outputs. Any problem with voltage selection will be pretty obvious.
     
  6. dlucy

    dlucy dlucy67 (Doug) Subscriber

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    Started installing the components on the tone board tonight. Lots of low noise 2% metal film resistors from Vishay CCF series:

    IMG_8433.JPG

    I did find one minor issue with the silkscreen labeling on this board:

    IMG_8431.JPG

    luckily R713 and R714 are the same value....
     
  7. stereofun

    stereofun Super Member

    Messages:
    1,190
    Location:
    Tucson, AZ
    Nice work ! Those 3 screws holding down the lamp cover caused a short on my Eight lamp rail - entirely my fault - turned out a wire got stripped as it was halfway stuck underneath one of the screws as I snug it down.
     
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  8. smurfer77

    smurfer77 Super Member

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    1,331
    Location:
    San Francisco
    I suspect it is closer to the 5000 (at least it is, in terms of topology).

    Thank you to the OP for all of the excellent pictures and documentation.
     
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  9. Leestereo

    Leestereo Super Member

    Messages:
    1,986
    Location:
    Ottawa, ON
    Setting to the voltage selector to "117V" is fine. So is using "127V", its not going to cause any excessive distortion in by itself; a 5% lower power supply rail voltage is not that significant. One can monitor the voltage at the main capacitor, make the amplifier adjustments (e.g., bias) and then determine which setting of the voltage selector gives voltages closest to that specified in the schematic.
     
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  10. dlucy

    dlucy dlucy67 (Doug) Subscriber

    Messages:
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    The tone board has been completely rebuilt with metal film resistors, C0G NP0 MLCC caps, Nichicon low leakage KL electrolytic caps, and WIMA metalized polyester film caps where possible. All-new Zener diode and transistors, especially the noisy 2SC871 devices replaced by KSC1845F devices.

    IMG_8448.JPG IMG_8456.JPG IMG_8461.JPG
     
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  11. dlucy

    dlucy dlucy67 (Doug) Subscriber

    Messages:
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    Location:
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    IMG_8442.JPG

    There were a few more typos in the silkscreening... C061 should read C601
     
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  12. perryinva

    perryinva IS it vintage????

    Messages:
    2,178
    Location:
    Richmond, VA
    Great thread! And how timely! I had a 7000 given to me by a friend that was moving and had never used it. It was his fathers. Sat in his attached garage for about 20 years. I opened the case, vacuumed out all the dust and spider debris, and cleaned the face plate. Besides some oxidation on the Tape Monitor switches and noisy input selector when switching, and a few burnt out dial bulbs, it works perfectly. Amazing. I LOVE that it has two phono and two tape selects, and how the AM/FM dial and meters goes black unless you use the tuner. Independent L&R tone, and independent power button! Sweet bulb preservation! All pushbutton word caps are gone & the silver paint on the bezel needs a repaint, but other wise in perfect cosmetics. I printed some white ptouch labels on clear heavy duty labels. Fine for now.
     
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  13. americannigh

    americannigh Active Member

    Messages:
    115
    Location:
    Bellevue, WA
    Awesome job on the rebuild, Doug. Keep up the good work!
     
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