The AU-X1 is, like, so hot right now.

Discussion in 'Exclusively Sansui' started by slimecity, Sep 24, 2017.

  1. slimecity

    slimecity Super Member

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    Right, I'll try those - Cheers Kev. I did find some conflicting info on the MFE's. I tried again on the other module today. I'm still convinced I have blown jfets. The voltages start to go funny there and at Trs 02-09.
     
  2. kevzep

    kevzep Its all about the Music Subscriber

    I don't think those transistors will be causing this particular issue though.
    Are the transistors you've replaced blown? If they aren't I wouldn't replace them.

    Take the FET's out and jam a couple of transistors in there, some NPN generic TO92, then you can eliminate the FET...
    I did that with my G7700 years ago...
    FET's do go bad, but not as often as you'd think....
     
  3. slimecity

    slimecity Super Member

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    Thanks Kev - will try that. None of the trannies are blown however some were giving weak readings on one-way of the 6-way test, and I thought they may have been misbehaving in-circuit. I am just trying to rectify some off-voltage measurements and replacing trannies one by one with reliable new ones.
     
  4. slimecity

    slimecity Super Member

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    OK. Tanties to one side, I donned my scuba gear and retrieved the X1 from the bottom of the harbour, got some counselling and tried again.

    After frying a MJ21194 I realised I hadnt really inspected the resistors mounted on the heatsink block (R701-712), including the emitter resistors (R713-724). So the SM states that the smaller ones are meant to be 47ohms. Ummm, I am getting between 3-5ohms on all of them - I double checked with a meter & a component tester. I Also removed and tested all the emitter resistors - these were all OK except for one that is measuring 1meg-ohm!

    So Im hoping this may explain my batshit crazy readings. Honestly I have gone over the boards at least 10 times and tested all the onboard resistors too, it all seems to check out otherwise.

    So anyway, the SM states that R701-712 are meant to be 47ohm, but I swear that the colour coding is yellow-violet-brown (not yellow violet black), which to me reads 470ohm? Any thoughts on this?

    Im otherwise feeling pretty stoked that I have found something that appears to be significantly wonky.....

    Cheers!
     
  5. kevzep

    kevzep Its all about the Music Subscriber

    I think you'll find they are supposed to be 4.7Ω.
     
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  6. slimecity

    slimecity Super Member

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    OK, that sucks. At least having one emitter resistor super high could explain my issues, hopefully?

    Otherwise - I'll shut up now.....
     
    Last edited: Nov 13, 2017

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