SANSUII BA-3000 PROBLEMS

Discussion in 'Exclusively Sansui' started by pppoffice, Aug 30, 2017.

  1. pppoffice

    pppoffice AudioBear Subscriber

    Messages:
    516
    Location:
    South of KC, Missouri
    I have two Sansui BA-3000 Amplifiers that have been giving me nothing but problems. They have both been not working now for the better part of a year. I have started a couple of post here in the past trying to figure out what is wrong with them but the posts always seemed to fizzle out and I have never been able to get either of these amps back to working. The one I am working on now has had all of the caps except for the large 22000 uf/80 volt replaced with high grade Panasonic and Nichicon caps from Mouser Electronics. This BA-3000 has the correct voltage on one of these large 22000 uf caps but there is no voltage on the other of these caps. When I check the B+ voltlage on the F-2512 board it is there. I do NOT have the + or _ 35 volts on the F-2512 Board. I do have the +60 volts on the F2512 board but I do NOT have the -60 volts on the F-2512 board. I have a F-2507 Power Supply board plugged in that has proven to be good but until I can get my +-35 volt issue and my issue of not having any voltage on the one 22000 uf large caps I am not even trying to plug in my F-2508 boards in. I also want to add that the F-2511 Speaker Protection board seems to be working fine as the amp does go out of speaker protection and the green light lights up. I love these BA-3000 amps when they are working and it is really bothering me that I can't seem to get either of the BA-3000 amps that I have to work. I am not an electrical engineer or anything close to that but I have been working on my own audio gear for some 40+ years. My soldering skills are great, I have good testing gear, and I pretty much understand most everything when it comes to the parts that make this amp work. I have a huge supply of components for the BA-3000 Amps but none of this so far has helped me get these BA-3000 Amps to work. I sure could use some help getting these 2 amps working again.
     
  2. Hyperion

    Hyperion Roobarb & Custard Subscriber

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    BA-3000's are pretty special, not everyone can work on vintage gear and get it working properly. But the finer points..... if these have eluded you up to now, then I think its time to re-think your strategy restoring these units.

    Try re-reading some of the BA-3000 threads that have been on AK, make notes, and re-visit some of your actions.

    Very, very hard to convey over an Internet forum, either you've 'got it', or you haven't, that's my humble opinion.
     
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  3. pppoffice

    pppoffice AudioBear Subscriber

    Messages:
    516
    Location:
    South of KC, Missouri
    My oldest BA-3000 acts like it should be fine. I have all the voltages where they are suppose to be and I am not blowing any fuses at all. It comes out of speaker protection just fine too. The problems I have with it is that the Bias voltage starts off very low and slowing increases to where I have set it to be which is 20Mv. The speaker outputs set zero out just fine. I am mostly concerned on how the bias is acting. It will slowly increase to where I have set it and then sometimes it will go way over the 20Mv and when I drop it back to 20Mv then it starts going down until it is way below the proper setting. Right now when I set it, it will level out at the proper bias setting in about an hour. I have then connected my CA-3000 and given it a try. It will start off like it is going to be OK and then suddenly the left channel will go out and eventually it will just get completely quiet. When I check it out, no fuses are blown but some power transistors are bad. This is how it has been going on with this amp now for about a year. No matter what I do I can't get it to work properly more than 5 or 10 minutes. That's why I started on my second amp this week. I am using the power supply board out of the other amp but I just am having weird problems with voltages being where they should be. I have the 87 volts that should be on the large 22000uf caps at the F-2512 board where the 470uf caps are located but I only have the negative 87 volts on the one large cap with the other one showing maybe 1 to 3 volts. Like I also said, I have the positive 60 volts on the F-2512 board where it is suppose to be buy not the negative 60 volts. This is just really weird. I have never seen this status on the other BA-3000 amp even when it was working its worse.
     
  4. JOMARK911

    JOMARK911 Super Member

    Messages:
    2,504
    Location:
    Athens Greece
    Check the voltage regulator board next to the driver boards. Start there. There are some really finicky transistors on this board , apart from the caps and resistors that go high z.
    As John (Hyperion ) said BA3K are notorious for their problems. I had them too , I had to swap all drivers and pre drivers on both the units I have. Maybe you should try a certified technician among the AK members.
     
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  5. vigman

    vigman SUBSCRIBER

    Messages:
    4,078
    Location:
    Valencia CA
    Ok I'm confused.... you have 2 rig's and they are both unhappy.... If you do not power these up.. how are you getting these measurements ??
    1) Do you have a DBT ?
    2) There has to be some smoked traces ( or other badness ) to get these into this condition...
    3) I can walk you through IF you do exactly what I tell you.. step by step and not jump ahead or do your own experiments.

    I have posts on my rebuilds I just smoked one of mine and 45 bucks later it's back alive again.

    So if you will do that we can proceed....

    Mike
     
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  6. vigman

    vigman SUBSCRIBER

    Messages:
    4,078
    Location:
    Valencia CA
    There are 2 versions of the BA-3K and the driver boards AND the main out bricks are different.
    Pick 1 of the 2, take a series of pix & post em.... clear off the workbench and we can start visual inspection (s) and measurements...
     
  7. Overundr1

    Overundr1 AK Subscriber Subscriber

    Messages:
    2,315
    Location:
    Mississippi
    VD1212's replaced?
    Zener diodes replaced?
    Have to get that power supply correct first
     
  8. vigman

    vigman SUBSCRIBER

    Messages:
    4,078
    Location:
    Valencia CA
    If this was an amp I bought of E bay.. I would start here:
    1) Unsolder both output bricks AFTER making docs of the wiring order & Lots of pix.
    2) Remove the 2 driver boards 2507. Tag which one came out which slot.
    3) Remove the 2508 Power supply board.
    4) Unplug the power to the input board AND the meter boards MARKING each connector for proper re install.
    5 ) This should leave the 2511. I assume the factory wire tag numbers are still on the female connectors, if not MAKE SURE YOU MARK EACH ONE PRIOR TO REMOVAL !
    AGAIN LOTS OF PIX !
    6) Remove the 2511 and do a CLOSE INSPECTION of the printed circuit side of the protect board where D0-1 & D0-2 are mounted...
    7) gather up 2 , 200 ohm 1/4 watt resistors...
    FULL STOP ~
     
  9. pppoffice

    pppoffice AudioBear Subscriber

    Messages:
    516
    Location:
    South of KC, Missouri
    The two BA-3000's that I have DO NOT smoke or cause any fuses to blow. They both power up just fine with both of them coming out of speaker protection and they both have the meter lights come on. My oldest one will allow me to set the bias bit the bias goes up and down all on it own from the time it is powered up until it is powered down. This oldest one allows me to zero the speakers out just fine and they will hold the speaker settings just fine. It is the bias that goes crazy up and down on the oldest one. The second one I have will power up just fine with the meter lights coming on and it goes out of speaker protection mode just fine. It doesn't blow fuses. I only have the F-2508 Power Supply board plugged in at this time without the F-2507 Driver Boards plugged in until I can figure out why I don't have the +- 35 volts on the F-2512 board. The F-2512 board does have the +- B+ voltage of about 87 VDC but does not have the +- 35 VDC. The F-2512 board also has the +60 VDC on this board but NOT the -60 VDC. The only other voltage problem I see on this second BA-3000 is that I have is the one of the large 22000uf caps has the +87 VDC but the other large 22000uf cap has only 1-3 VDC and not the full 87 VDC that it should have. I can follow instructions just fine so long as you don't go into deep electronic engineer talk. I understand most anything you will mention about this amplifier but I don't know the engineer talk.





     
  10. pppoffice

    pppoffice AudioBear Subscriber

    Messages:
    516
    Location:
    South of KC, Missouri
    I have been working on keeping these two BA-3000's going for over 15 years. It has just been the past year where they have went nuts on me. I have every wire connection possible down on paper, lots of pictures, and all connectors are marked with the original Sansui markings or my markings so that this amp can go back together if I were to take every piece of it apart and put it in a box. I have every piece of information on how to reconnect every connection on the F-2511 board. I have had this board out of the amp for cap replacements and since then to check components to be sure they were working properly numerous times. Both of these BA-3000 amps will come out of speaker protection mode when the F-2511 is in each amp. I have done what you asked of me and I do have 2-200 ohm 1/4 watt resistors.



     
  11. pppoffice

    pppoffice AudioBear Subscriber

    Messages:
    516
    Location:
    South of KC, Missouri
     
  12. pppoffice

    pppoffice AudioBear Subscriber

    Messages:
    516
    Location:
    South of KC, Missouri
    And by the way, I get these voltage readings because I already explained, both of these amps will power up without blowing fuses and will come out of speaker protection mode.
     
  13. pppoffice

    pppoffice AudioBear Subscriber

    Messages:
    516
    Location:
    South of KC, Missouri
    I have seen at least 2 versions of the BA-3000 over the years. Both of the amps I have are the Japanese model that operate on 100 volts AC. I use step down transformers on both of mine so that I am not operating them on 120 Volts AC.


     
  14. pppoffice

    pppoffice AudioBear Subscriber

    Messages:
    516
    Location:
    South of KC, Missouri
    I forgot to say that both of my amps have the same boards in them and are identical.

     
  15. pppoffice

    pppoffice AudioBear Subscriber

    Messages:
    516
    Location:
    South of KC, Missouri
    That is exactly what I am trying to do and the reason that I only have the PS board plugged in at this time. I do not have the driver boards plugged in until I can find out why I am having the voltage problems. Yes, I have replaced both VD1212's with 4108 diodes in series. I have NOT replaced the Zener diodes as they check to be good but I do think that I have 1N5245BTR diodes in stock. I have the cross reference list for transistors and diodes that is listed here on AudioKarma.
     
  16. pppoffice

    pppoffice AudioBear Subscriber

    Messages:
    516
    Location:
    South of KC, Missouri
    I'm sorry, I meant to say 1N4198 diodes in series to replace the VD1212 diodes.
     
  17. vigman

    vigman SUBSCRIBER

    Messages:
    4,078
    Location:
    Valencia CA
    OK WELL... Pick 1 AMP to fix, after stripping it down, post a pix of the front & back of the 2511.... ( post your inspection ) .....
    Oh have you replaced the DC & BIAS pots with multi turns ?
    IF both the amps power up and come out of protect, all that means is you have a working amp with minimal DC offset OR an amp with 2 blown AMPS.
    All " protect " does is protect your speakers from MASSIVE DC OFFSET
     
  18. pppoffice

    pppoffice AudioBear Subscriber

    Messages:
    516
    Location:
    South of KC, Missouri
    Yes, I understand what the speaker protection does. Since so many of the problems I have heard that people have with their BA-3000's is related to speaker protection (which keeps the amp from working at all) I made mention of it so that it was understood that speaker protection was NOT an issue with either of my amps.

    I am handicapped and 75 years of age so because I am an old F*** and in a wheelchair to boot, it takes me a bit of time to do the pictures and things that require me to move around. My computer is NOT where my shop and bench is so I have to stop and go over to a totally other building to get pictures of do what is asked. Now that this is understood, I have taken pictures of the Amp and the PS board and the two driver boards. I haven't had the time yet to pull the speaker protection board but I did take pictures of it to show it in the amp. Attached are pictures of the PS Board, Right Channel Driver board, and Left Channel Driver board. Pictures of the amp and speaker protection board still in the amp will follow soon. I will have to pull the Speaker Protection board to take detailed pictures of it later.

    After just trying to upload all the picture files that I have I now know that if there is an email address or other method of getting you all the picture files that I have will go a lot faster. Trying to load all the picture files that I have ready for you to see will take a week to get to you in this manner.


     
  19. vigman

    vigman SUBSCRIBER

    Messages:
    4,078
    Location:
    Valencia CA
    Ok understood.. It's best to post pix here,so others can benefit at a later time. We need to take baby steps... The 2511 ALSO has the DC rectifiers on it to give us the Bi Polar 65 volts for the big caps. That is the supply for the output bricks... if that isn't right everything else slides downhill in a hurry. I will go as fast ( or slow ) as you need to go. BUT we need to stay on track, have focus and nibble on 1 issue at a time. All I want now is top & bottom pix of the of the 2511. I am 60 and retired so doing remote control repair is a mental challenge which I enjoy. Tomorrow I'm having a tooth extracted ( JOY ) so I will have some recoup time and can get wrapped up it this. I prefer not to know the history of things....( as far as amps go ) We are starting from scratch, assuming nothing except it's broke as a joke.

    Mike
     
  20. pppoffice

    pppoffice AudioBear Subscriber

    Messages:
    516
    Location:
    South of KC, Missouri
    OK. I understand all about tooth extractions. Two weeks ago I had my last 2 teeth pulled. One of them was the only one in my mouth that was painful but not too bad. Now I am getting ready for implants. I use to spend a lot of my time at the KC, MO VA hospital but since the last 2 months I now am pretty much back to being fairly healthy. At least for me. I no longer go in twice a week (50 mile drive each way) for wound care. Maybe now I can start enjoying my retirement.

    Here are pictures of the top and bottom of the SP board. I have saved a lot of other pictures taken of the 2 driver boards, the power supply board, and the bottom of the amp if you should need them down the road.
     

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