Sansui 1000a restoration & Modification questions

Discussion in 'Exclusively Sansui' started by birdyman, Jan 25, 2011.

  1. markn2wae

    markn2wae Mark T N2WAE

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    My Sansui has 4 bias pots.

    I never really looked into bias pot modifications, all I would suggest is to copy the schematic with the 4 pots, it may be a little different than just "multiplying" the original circuit.:scratch2:

    Sorry I can't be of more help.:sigh:

    Mark T.:music:
     
  2. naderpe

    naderpe AK Subscriber Subscriber

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    Mark you are always a lot of help!
     
  3. birdyman

    birdyman New Member

    Messages:
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    I will do 4 pot schematic mod as you suggested.


    Last night, my Sansui 1000a received LED treatment. I used 2 LEDs serial on rectified heater supply. I looks way cool.
    I just need to do some chassis cleaning. I am using Simply Green spays. Can anyone know any better spray or cleaner?

    And what can I do about disappearing Labels on face plate??

    Thanks for reply
     

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  4. markn2wae

    markn2wae Mark T N2WAE

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    Blue LEDs? Hmmmmmm.....

    If "way cool" is the look you are going for, go for it, but IMHO it destroys the "vintage look" of the receiver (you are breaking my heart! :tears:)

    As for the front panel lettering maybe you can get a "parts" unit with a better panel?:scratch2:

    Mark T.:music:
     
  5. birdyman

    birdyman New Member

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    26
    I am spending way too much time on listening the receiver without making any progress on 4 pot bias modification. The more I listen the amp I like it more. I thought may Pass clone Aleph J is the best amp period. I am starting to getting shaky on that statement. That glow of amber has some kind of hypnotic black magic voodoo quality. So many years of being SS guy, I tend to put my hands on the parts of amps. I just keep remind my self before rude awakening from unintended CPR.

    What is official & practical wattage of Sansui 1000a per channel?
    I just scored Scott 340b which uses same OP tube and it is marked 35w/ch on chassis. I thought Sansui 1000a was 50w/ch?? I think both uses same B+ (470??).
    Why OP ratings are different?
     
  6. markn2wae

    markn2wae Mark T N2WAE

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    "Official" Sansui 1000A output power.

    The Sansui 1000A service manual states 100W total Music Power and
    an RMS power of 40\40 Watts per channel at 1% harmonic distortion.

    Mark T.:music:
     
  7. birdyman

    birdyman New Member

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    26
    Should Power transformer get hot?

    Amp is sounding great without any issues, but power transformer gets hot to touch(painful but I can hold my hand on it if I have to) after playing mid volume for 2 to 3 hours with cover removed. I have not done anything for bias or can caps yet. It sounds great though. Is this normal temp or mine is too hot?
     
  8. BinaryMike

    BinaryMike Pelagic EE Subscriber

    Power xfmr temp *might* be normal, but if you haven't attended to output stage bias, all bets are off. In vintage tube gear of any stripe, this is a critical item that should get attention prior to extended listening sessions. And those old lytics are a major liability as well. Make very sure they aren't overheating, and replace 'em at the earliest opportunity.
     
  9. birdyman

    birdyman New Member

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    26
    I guess I need to get back to work on caned caps and bias. Oh well....
    Thanks Mike
     
  10. larryderouin

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

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    The biggest reason the PT gets so hot is threefold..........
    1.) 2 7591's sitting less than 1/4" away,
    2.) that 600oHm/6KoHm Ceramic Dual Power Resistor sitting up against it. More so than the tubes.
    3.) No real venilation at that point as 3 sides are blocked in by a PT, an OT, and a heatshield across the middle from the edge to between the OT's.

    Once you get it back together, sit a small fan blowing OUT (UP) directly over the resistor on the top. Secure it someway.

    Mine runs 20 - 7 and gives me no end to enjoyable sound.

    the "hotter"you set the BIAS, the hotter the area will be. Bias them slightly cool (I've got mine about 25ma on 470v. )

    Larry
     
  11. I recently bought a Sansui 1000X and a beautiful set of Sansui SP-2000, (that need to be refoamed) but I got the original packaging, wires, service manual, The receiver was a sort of time capusule, one channel is louder than the other and I was told the cap's are probably dried out, I'm guessing this model is Solid State, (not tubes) I'm very new at this stuff, since I have the service manual should I attempt this repair myself, I mostly Re-work speaker's and I've already screwed up a Fisher 2000 Bass POT. because I could not get the set screw off the knob so I've got to replace the bass control and all I wanted to do was take off the face plate to replace the lamps!
     
  12. larryderouin

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

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    DarylEdward.

    How about starting a separate thread detailing EXACTLY what problems you have and what you want to do with the 1000X.

    1.) You'll probably get more responses that pertain totally to your unit.
    2.) You won't be "threadjacking".
    3.) Someone with that unit may be able to walk you thru a repair to it.

    BTW. Most set screws for knobs on Audio gear are 1.5mm.

    Larry
     
    Last edited: Feb 5, 2011
  13. nosirrah

    nosirrah Moderator Moderator

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    He's right Daryl Edward, please do start your own thread, easy to do.
    Welcome to AK and the Sansui forum!
    Start a thread and tell us more!
     
  14. teebee

    teebee Active Member

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    Disappearing letters on front glass:

    The print is recessed shallowly into the rear of the glass. You can mask and spray lightly with a very opaque paint or pigment and then carefully scrape diagonally over the printed recesses with a new and flat razor blade. I did it and it looks and works great!

    A lot of my lettering paint was missing.
    My front panel is going to need a few dry transfer decals.
     
  15. markn2wae

    markn2wae Mark T N2WAE

    Messages:
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    Location:
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    Thats the first time I have heard of restoring front dial glass lettering (the method may be helped by the "recessing" of the printing, to be 'left behind" after the razor blade operations, cool!)

    Good luck with the front panel lettering, I've never tried a restore here yet.

    Mark T. :music:
     
  16. Pio1980

    Pio1980 AK Member Subscriber

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    Any good working germanium signal diodes should be left alone and in place, I don't recall offhand if they were used in the AM or FM detector, but replacing them with different types can cause problems.
    Germanium transistors are something else, they can develop noise or other problems and are generally not directly replaceable with silicon type without some re-engineering of the circuit. Generally, just recap the phono board, check the resistor values with a DVM, and troubleshoot problems if they occur.
    Selenium bias rectifiers are generally replaced with silicon as a matter of course, I dunno if the oem disc silicon rectifiers are considered unreliable.
    The smaller electrolytic capacitors in the signal path should all be replaced as a matter of course, along with all of the grey Suzuki caps.
     
    Last edited: Nov 30, 2016
  17. larryderouin

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

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    If you feel that the Ceramic Power resistors between the PT and the 1st OPT are out of spec, OR are physically cracking or breaking down of the ceramic, replace them with HI-WATTAGE DALE Aluminum resistors. Mount them in different places on the chassis to break down the heatload from being in one place. Overall I think the heatload is probably the same, but being distributed, spot heatload is diminished greatly. 100_4262.jpg

    Here's the link to the thread I put up on it. http://www.audiokarma.org/forums/showthread.php?t=536768
     
  18. germannoramb

    germannoramb New Member

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    Hi folks, first at all, excuse me my english.
    I think the most people here in thi VERY VERY GOOD PAGE are hobbyists and no professional, in my case, i can read all the opinions where you the professional know how to do that about change parts of this beautifull receiver but, the people like me, no professional, have little or not idea what parts have to by or what parts are the same or better than original, for example, you speak about change GERMANIUM DIODES but no body say what typy, manufacturer or values, with caps, have the same problem with caps, PIO, POLYPROPYLENE, where and values, etc...... for me, that´s very relevant because in ebay i can search for parts but without names o brand or type, it´s very difficult.

    The schematics have simbols and it´s clear for OIL CAP, CERAMIC, MICA, MYLAR, M.P CON., i read WIMA, RUSSIAN, UF TYPE DIODES, etc,etc... on Ebay, where can find each one of them, like i say, i´m not professional for tubes but i have worked in a lot of solid state amplifier., i love work with amps.

    I hope you can help me because i want to restore my beautifull Sansui 1000a but after read tons of information, i don´t know finally what type of parts are good for me.

    I hope for your answer for my LITTLE PROBLEM.
     
    Last edited: Jul 11, 2017
  19. Dave C

    Dave C Super Member

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    The stock 1000a phono section is nothing to write home about, I'd have no problem changing it out, but do a neat job.
     
  20. larryderouin

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

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    germannoramb; Parts is parts. The only difference between parts for Solid State and Tubed stuff is the voltages. 600v or 630v for ALL REPLACEMENT caps below 1.0uf. Brand is up to you. Find out if Mouser or Digikey sell in your country. If so, even better. Stay away from Ebay for parts. The output coupling caps only run up to 400v from 250v. These are huge anyway at those voltages and most .33uf 400v are absolutely gigantic. 600 or 630v won't fit.

    For small electrolytics, go with Nichicon UPW/UHE series in the power supply and UKL in the signal path. If you stuff the CAN CAPS, Nichicon ucy are fine. They are slim and long and fit the can well. Go up in voltage 50v higher on the electrolytics.

    UF Diodes aren't needed. Use regular 1n4007 or 1n5408 (1A and 3A).
     

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