Sansui BA 3000 amp and CA 3000 preamp question?

Discussion in 'High-End Separates from Years Past' started by Stevep914, May 18, 2016.

  1. Stevep914

    Stevep914 New Member

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    HI everyone, I am a newbie to this forum- don't know why it took me so long... When I moved to Mexico 24 years ago, I made one trip with a motorhome just to transport my audio equipment - too many pieces to list. The guts of the system are two Sansui BA 3000 amps run mono through a CA 3000 preamp, all into two Cerwin Vega D 9's rated at 4 ohms each. This all ran ok with wonderful sound for several years in Canada. After several years in Mazatlan, Mexico ( yes, on the ocean, and we have salt air) one amp gave up, and I continued to run the other amp stereo through the preamp. Still sounded good, but definitely lost some punch. Then the other amp lost a channel. Everything went into storage bags, and I was forced to add an Onkyo receiver to power things ( the best thing I could find new down here) Definitely does not do the speakers justice. I am now going to deliver the three units to a reputable repair guy in Tucson for refurbishment. The question I have is: I just looked at everthing inside, and don't see evidence of major corrosion or deterioration; but did notice a sticker on the back of the amps indicating mono(340 watts) into a minimum 8 ohms. DId I damage these by powering the 4 ohm Vegas, or are they stout enough to handle the lower ohms? Other than repair, would I be better to get a reconditioned big power Adcom or like amplifier that is designed for lower ohms? Thanks in advance, Steve
     

     

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  2. nj pheonix

    nj pheonix AK Subscriber Subscriber

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    I'm not the expert here but I'd guess unless you were making your neighbor's ears bleed, I highly doubt you killed them. You are talking 35 some odd years. How many things do you have that went 35 years without an issue?
     
  3. blhagstrom

    blhagstrom Mad Scientist, fixer. Subscriber

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    Those units have a design issue with the boards.

    They used vias, also called pass throughs. There are board traces that go from one side of the board to the other by a hole with a rivit type collar. The solder breaks loose on the collar.

    Not all the amps used them. I think all the preamps did.

    The amps that had them are on the boards inside the amp blocks. The blocks must be removed and disassembled to find them,

    The preamp has over 100 of them, many hidden under the tape and near the switches.

    All of them must be found and repaired by sucking out the solder, inserting a short wire and soldering that wire to the trace on each side. The trace may need to be scraped clean a little to get a good joint.

    If that is not done to these, intermittent problems will drive you and your repair guy crazy.

    It is a LOT of work. The preamp must be completely taken apart.

    Once done, they are some of the nicest gear I have ever had the pleasure to hear.
     
  4. nj pheonix

    nj pheonix AK Subscriber Subscriber

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    Does that go for the similar period integrateds (au-9900,11000, 20000)?
     
  5. totem

    totem AK Subscriber Subscriber

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    The pass throughs are a long standing issue on the CA 3000s, as far as running the BA 3000 mono into 4 ohms I
    would never do it myself.
    Take a look at the output rating in stereo @ 8 ohm and 4 ohms, that pretty much says it all. { very little margin }
    I have had several CA3000s and BAs.
     
  6. nj pheonix

    nj pheonix AK Subscriber Subscriber

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    This is sort of an academic question. I personally have no intention of digging into one of these. I have noticed people fabricating pcbs for other pieces ( not these specifically) I was thinking that this would be a time consuming effort ( going through a board and remaking (with wire and scraping) these connections. Perhaps doing a run of reproductions might yield better results faster and cheaper ( when you figure in labor time).
    Just a thought.
     

     

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  7. Stevep914

    Stevep914 New Member

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    I played a bit with the two amps and preamp, to try to determine what is wrong with each component; or more accurately; what each component won't do. FIrst, I plugged each unit in, and now all three power up. I then hooked up amp "A" to the preamp, and a cd player to the preamp. Speakers connected to amp "A" Got full sound out of the right channel, nothing from the left. It cut out after about two minutes to nothing. Meters on the preamp showing input both channels, although weaker on the left.Meters on the amp, right channel only. Then I hooked up amp "A" to an Onkyo TX 8555 receiver using the preamp portion of the receiver only, and got extremely low volume right channel only, with the volume control maxed out,
    I then hooked up amp "B" to the CA3000, and got nothing from anywhere,; preamp showing signal on the meters from the cd source. NO action on the amp meters. I then hooked amp "B" to the Onkyo, and got low volume sound both channels, with all the meters showing something. A bit weaker on the left. My preamp and one amp is definitely in need of reworking. Amp B seems to function, but not at volume using the Onkyo as a preamp. I am now confused about using the Onkyo as a preamp, as the B power amp seemd to produce both channels, but very low volume. In other words, could not get any kind of decent volume, using the Onkyo as a preamp. I am out of preamp options with what I have to go any further. I guess bottom line: it all needs a tech, as it is beyond me.
     
  8. Sriskie

    Sriskie AK Subscriber Subscriber

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    I don't think I'd be alone in saying that I wish I had your problem. Those Sansuis would be my end game setup, get them fixed up and enjoy. :rockon:
     
  9. blhagstrom

    blhagstrom Mad Scientist, fixer. Subscriber

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    Too many boards, double sided boards (thus the need for vias) not enough CA/BA out there to justify the effort and cost.

    It is a stupid amount of work to re-do them. But they are worth it.

    If the pre-amp is not reworked, all bets are off. It works, it doesn't, it's fixed, no it's not, repeat. I did one that went through a shop a few times and failed each time it got home. It worked when it arrived here and when I peeked into it, it failed.
     
  10. Stevep914

    Stevep914 New Member

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    I sort of feel I have nothing to lose ( but some $) in getting these fixed. I had forgotten how good the sound is ( even with only the one channel while it worked briefly) The Onkyo I have been using, just isn't up to the task; even though it still sounds better than all of the stuff around here. Looking at replacement to get comparable performance seems that I am still looking at a lot of older equipment that may need to ultimately be reworked anyway. Thankyou all, for your input! Steve.
     
  11. blhagstrom

    blhagstrom Mad Scientist, fixer. Subscriber

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    Restoring them is a no-lose situation.
    It is an investment.
    The $ pain only lasts until you fire them up and sit down and listen.

    You can make more $ but they do not make more BA/CA 3000s
     
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  12. rcs16

    rcs16 AK Subscriber Subscriber

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    probably better served in the Sansui forum.
    these ratings are for full power, so if you are not pushing it to these limits, you do have a certain bit of margin with load impedance.
     
  13. Stevep914

    Stevep914 New Member

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    All three units are headed for Tucson, Az on the 3 rd of July to be reconditioned. May take awhile, but I am looking forward to the great sound again! As I age, the ear splitting volume of the old days is not so important. I will make a decision then what direction I go in hooking up one amp or both. Thankyou all for your input!
     
  14. dr*audio

    dr*audio Fish fingers and custard! Subscriber

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    The AU-9900 and AU-11000 do not have feed thrus on any board. I never worked on a AU-2000 so I don't know about that one.
    The BA3000 has no feed thrus as far as I recall, just the CA3000.
     
  15. nj pheonix

    nj pheonix AK Subscriber Subscriber

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    Thanks Doc
    I'm in for a pound so I'll find out:D
     

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