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Help needed- Sansui 9001

Discussion in 'Exclusively Sansui' started by Shaun b, Aug 5, 2018.

  1. Shaun b

    Shaun b Member

    Messages:
    74
    Hello to everyone. A couple of days ago I stumbled across a big one, the 9001. I’m embarrassed to say what I paid but it was pennies really. For the price, I didn’t even ask if it worked. I got it home and have it a good cleaning, cleaned pots with deoxit and let it dry over night. Next morning I plugged it in to a DBT and hit the switch and my bulb went very dim and Sansui lit up. I plugged into outlet and powered up and it came on but no sound. All meters are working and I get sound from headphones but no speakers. OT transistors 5 and 6 got really hot but they test ok. I replaced some fusible resistors on driverboards(not all because I didn’t have enough but I have already ordered enough to replace all on both boards as well as all caps. I guess I’m confused as to why DBT was good and meters and headphones but no speakers. Am I missing something? Years ago it’s little brother got me with the remote plug in the back not being plugged it so I quickly looked for that but nope, it’s not that. Any advice or direction would make an old man happy. Anyone smarter than me(all of you) got any help to offer? Thank you in advance for any help.
     

     

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  2. Sansuiman

    Sansuiman Active Member

    Messages:
    321
    Location:
    St. Louis, Missouri
    Possible issue with the protect circuit or protect relay not setting after power up. The headphone jacks are not routed through the protect circuit, while the speaker outputs are. Regrettably, no protect indicator LED was provided on the 8001 and 9001, so you need to listen for the click of the relay hitting home a few seconds after power up.

    If you have outputs getting hot, you probably have A DC offset or bias issue that needs addressing. That could be causing it to stay in protection mode, so get those measurements checked and propely set first then see where things stand.
     
    Shaun b likes this.
  3. kevzep

    kevzep Its all about the Music

    Could be anything from switches wrongly deployed, something is unplugged in the amp somewhere, Dolby switch in the wrong position, tape monitors switches, speaker selector switch in the wrong position.
    Protection engaged and not pulling in the speaker relay, huge DC offset, bias running away....

    You need to start at the beginning and work through the power amplifiers and make sure everything is all good there, voltages are on point, fusible resistors have been replaced, bias and DC offset trimmers replaced, amp adjustments made. This is where I would start.
     
  4. Sansuiman

    Sansuiman Active Member

    Messages:
    321
    Location:
    St. Louis, Missouri
    Kevzep is on the money with his advice. One other item I'd add is that unlike most big Sansui's, the headphones automatically cut off the speaker outputs on the 8001 and 9001, so you cannot have headphones plugged in and have the speakers working concurrently.

    If you are getting sound (i.e. tuner) from the headphones, then you should have sound from the speakers without headphones connected - assuming the main amp and protector are not malfunctioning - irrespective of the the tape/dolby/aux settings.
     
  5. Shaun b

    Shaun b Member

    Messages:
    74
    If I unseat the 2 driver boards it comes out of protection. I should have mentioned that in the original post. My bad.
     
  6. kevzep

    kevzep Its all about the Music

    Yep rebuild those power amp driver boards, and check all the output transistors.
     

     

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  7. Shaun b

    Shaun b Member

    Messages:
    74
    I ordered the parts yesterday, probably ship tomorrow, so its waiting time I guess
     
  8. Shaun b

    Shaun b Member

    Messages:
    74
    Thanks for the reply. I plugged the headphones in after I got no sound from the speakers. All knobs and switches are in correct position, its in the driver boards. If I unseat them, it comes out of protection. I also should have mentioned that when I first plugged it up, I got sound out of one speaker for about 10 seconds. When it cut off, I quickley powered down and saw that fuse 7 i believe had blown and that OT's 5 and 6 were very hot(the heat shield). Im still confused as to why the DBT is showing ok. Thanks again for the reply and i will let you know what happens when the parts get here
     
  9. kevzep

    kevzep Its all about the Music

    Because whatever has failed has either caused something to go open circuit, and is no longer able to pull current to light up the DBT, or a fuse is blown somewhere you haven't looked yet....
     
  10. Shaun b

    Shaun b Member

    Messages:
    74
    Do you know why the DBT is showing good? I will adjust offset and bias tommorow after work while waiting on parts, and will check again after new parts installed.
    Not a fuse but the other makes sense. Thanks for the reply. I really want to hear this thing make some noise. Patience escapes me sometimes
     
  11. kevzep

    kevzep Its all about the Music

    You have to be patient and methodical doing this sort of thing otherwise you will miss something, make a mistake and turn it into a bigger problem.
    Take your time, your patience will pay off.
     

     

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  12. Shaun b

    Shaun b Member

    Messages:
    74
    Understood. And Thanks
     
  13. KingBubba

    KingBubba "Too Much Stuff" Subscriber

    Messages:
    9,796
    Location:
    Brooksville, Fl.
    I have never seen a 9001. Would it be possible to post a pic?
     
  14. slimecity

    slimecity Super Member

    Messages:
    2,891
    Location:
    New Zealand
    The Dbt goes bright in the event of a dead short somewhere.

    what Kevzep is saying is that in this case, something has gone open, rather than shorted.
     
  15. Audio Fan

    Audio Fan First Class, Second Hand Subscriber

    Never seen a QRX-9001? They are a magnificent beast to behold.

    QRX-9001 -2.jpg QRX-9001 -1.jpg QRX-9001 -3.jpg
     
    tcdriver and slimecity like this.
  16. Sansuiman

    Sansuiman Active Member

    Messages:
    321
    Location:
    St. Louis, Missouri
    ^^^Good pics. I'll add a artistic shot of (one) of my own. One of the best looking receivers Sansui ever made IMO. Working on one, however, could make a monk cuss a blue streak. It doesn't get high marks for serviceability, in constrast to some Sansui gear that was fairly well thought out. Getting to some stuff for repairs is downright nasty. But, it's totally worth the tooth grinding frustration.
     

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  17. Audio Fan

    Audio Fan First Class, Second Hand Subscriber

    Very nice, I wish I had the technical skill to work on mine, it has solder joint issues. My tech won't touch it, unfortunately. (click that Full Image button and insert it into the body of your comment)
     
  18. kevzep

    kevzep Its all about the Music

    Find another tech, thats just ridiculous, a tech that wont repair......hilarious!!
     
  19. Audio Fan

    Audio Fan First Class, Second Hand Subscriber

    I know, but he's pretty good and the only one local to my remote area. I can't imagine trying to ship this beast.
     
  20. KingBubba

    KingBubba "Too Much Stuff" Subscriber

    Messages:
    9,796
    Location:
    Brooksville, Fl.
    Wow, What a beast. Thanks.
     

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