Ba2000 right channel sounds very distorted

Discussion in 'Exclusively Sansui' started by sansuibutch, Jan 18, 2016.

  1. sansuibutch

    sansuibutch Active Member

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    454
    I just checked them to see if they had voltage.. 2 were allready discharged from the grounded output, the other 2 I just led my meter on them tI'll they fully discharged. I put a screw in there and reflowed a few solder joints that looked questionable and reassembled it. Fired it up and have correct voltage on all 4 points to the outputs . I'm very confident with the new outputs this thing will finally come to life. I've been messing with this thing on and off for a long time. I ohmed out the output transistors and the one I circled is shorted. The rest seem fine. I know this is not a way to test them but hey I know a grounded output is definetly no good. Can't wait for the parts to come.. 20170314_192243.jpg
     
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  2. Overundr1

    Overundr1 AK Subscriber Subscriber

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    First time I have heard of a main cap with a missing retaining screw, no wonder we were having so much fun :)
     
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  3. sansuibutch

    sansuibutch Active Member

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    Tons of fun hahah . But I baught this amp basically to learn on. I've learned a lot. Now I need to get some troubleshooting skills. I have some equipment and just need some experience. I'm getting a slow start hahaha.
     
  4. Overundr1

    Overundr1 AK Subscriber Subscriber

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    I will say you cannot put a price on all the learning you have accomplished during this thread. If you do the 6 way diode test on that output it probably will show a failed condition, And for fun and practice measure the others and write down the hfe readings. Would be interesting to compare them to the replacements.
     
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  5. JOMARK911

    JOMARK911 Super Member

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    At last you are geting somewhere.
     
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  6. sansuibutch

    sansuibutch Active Member

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    454
    Your right about that. Thanks to all the awsome people including yourself on this site for guiding the blind. Hahah I have learned so much allready and hope to continue. I should have the new outputs tomarow if the 3 foot of snow that just fell doesn't slow anyone down. I read Echowars thread on testing them so I will definetly be comparing them. I hope the old ones are in bad shape. That would make me feel a whole lot better about shorting the one. Still don't really know how it happened. Right after the arc jumped to my meter I noticed I didn't have my wristband on for my static mat. Are the outputs that sensitive? I know I didn't actually short it to anything. An arc just jumped from meter lead to the solder joints I was probing.
     
  7. Overundr1

    Overundr1 AK Subscriber Subscriber

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    Make sure when you install the new ones you get the pnp and npn orientation correct or more excitement will occur. Be sure to look up the data sheets on the new ones to get it right Also take a minute with power off once you install them with new lightly greased mica to measure each one from the outside case to ground with power off to be sure they are located correctly and there is no ground path.
    TO-3 outputs are extremely rugged and will take a lot of abuse, however full rail voltage across their junctions usually bodes ill for their continued health.
     
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  8. sansuibutch

    sansuibutch Active Member

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    454
    Will do. Thank you again for the advice
     
  9. JOMARK911

    JOMARK911 Super Member

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    Good job man carry on.
     
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  10. sansuibutch

    sansuibutch Active Member

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    454
    I had some time today and installed the new transistors and reassembled. I checked all the transistor casses to ground and all was good.I plugged it into the dbt and turned it on and the bulb lit up. I disconnected both channel final stages and checked the wires that hook it to the amp and none have a path to ground. I then tuned it on without final stages hooked up and it turned on. Is there anything in particular I should be looking for?
     
  11. Hyperion

    Hyperion Roobarb & Custard Subscriber

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    You say the bulb lit up - did it stay the same brightness or fade a little, or not?

    Might be damaged driver transistors - collateral damage from the demise of the OP transistors perhaps?
     
  12. sansuibutch

    sansuibutch Active Member

    Messages:
    454
    I did notice when I was installing the final stages one of the black wires connecting the power supply to ground was on the wrong spade. It was on the one for the brown wire for the right channel. So basically I was sending the brown spade directly to ground. I know I removed these to tighten up them up some and can't remember if I fired it up like this to check voltage or not. But the spade for the brown that goes to the right channel has .177vdc and the spade for the orange wire that goes to the right channel has .300vdc . I don't if sending this voltage to ground messed somthing up or not. One step forward and two steps back hahahh hopefully not
     

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  13. sansuibutch

    sansuibutch Active Member

    Messages:
    454
    The b
    The bulb lit up and I didn't leave it on more than a few seconds. It didn't seem to be getting dimmer and the relay never clicked
     
  14. sansuibutch

    sansuibutch Active Member

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    454
    Can I disconnect the driver board from the outputs and turn it on to find out If my issue is on the driver board?
     
  15. Overundr1

    Overundr1 AK Subscriber Subscriber

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    Yes.
     
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  16. sansuibutch

    sansuibutch Active Member

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    454
    OK. It turns on and comes out of protection without the driver board hooked up. That is good but kind of sucks at the same time. Wich drivers should I be looking at on the board?
     
  17. Overundr1

    Overundr1 AK Subscriber Subscriber

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    pita steps ahead, now remove all four outputs, ensure to-3 sockets are not touching anything, reconnect without outputs and see if it comes out of protection. If it does then perhaps the to-3 outputs were reinstalled in wrong locations which would make the amp VERY unhappy.
    Might suggest doing one channel at a time leaving the other one out of circuit.
     
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  18. sansuibutch

    sansuibutch Active Member

    Messages:
    454
    With the driver board disconnected it comes out of protection. When I disconnected the outputs along with the driver board it stays in protection. Don't know if this helps or not.
     
  19. sansuibutch

    sansuibutch Active Member

    Messages:
    454
  20. sansuibutch

    sansuibutch Active Member

    Messages:
    454
    I'm pretty positive the orientation of the transistors is correct. And the t03 sockets dont seem to be touching anything. I'm thinking Hyperion might be spot on with the collateral damage post.
     
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