I need an Eleven GX expert.

Discussion in 'Kenwood-Trio/Kensonic-Accuphase' started by quaddriver, May 2, 2018.

  1. quaddriver

    quaddriver 120 What's per channel Subscriber

    working on of these that appears to be a virgin, its not blown up, just some scratchy controls, seriously bad solder joints on the 'MAC' (aka tone) board and burnt lights. so ok, easy fixes but it runs warm, too warm left side so I go to set bias. I cannot find any settings for the 11GX, eleven 1, 2, 3 and G but not GX and what I do find between here and diyaudio varies to the point where it appears to be rumor.

    The G book says 22 mv across the test pins on either channel which are the extreme ends of the emitter resistors. fine.

    VR1 and 2 are self explanatory.

    if I crank the pots to the least I get high 70's left and mid 40's right.

    there was a post somewhere that said the GX is a base exchange model of the G. no. while much of it is similar, there are acute differences on the amp board. I am able to track and correspond the topology but the ASO for the GX is utterly different from the G and there seems to be some value differences.

    Lettuce consider the left channel, which is too high and too hot. The G SM and SCM are on hifi-E. page 23, blow up to 250%

    the bias is set via VR1 which is in parallel with Re21 and flows current between Qe5 and Qe7

    The G spec is 22mv with Re21 at 47ohms and VeR1 at 100 ohms.

    All the silicon is the same but in the same positions in the Gx I find Re21 is 100 ohms and VeR1 is 200 ohms.

    at best, setting for setting the GX will flow half the current and it seems have twice the bias current otherwise.

    Does anyone have a GX or a GX SCM and are these parts values correct and/or is the setting 22mv or 45 which appears to be reachable. now I need to look tomorrow to see if the bias resistor for the drivers are the same, G vs GX as that could confuse things.

    now why the left channel is higher is simple - VeR1 is actually 250 ohms instead of the 200 found on the other side. I figure the bias difference is proportional to the error in the larger pot.

    the thermals are STV-4s and sure enough, let it stew to where the steel portion of the frame gets warm and the diodes are flowing and it does lower to low 70's, but still way too high (beyond me why these are mounted to the steel frame NEXT to the heatsink when ON the heatsink would be more direct.)

    At any rate, this is an expensive disaster looking for a place to happen. I have 100 ohm half watt resistors all over the place but 200ohm pots are going to require an order, unless we find that other values need to be used....

    any ideas?
     

     

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  2. quaddriver

    quaddriver 120 What's per channel Subscriber

  3. gort69

    gort69 AK Subscriber Subscriber

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  4. quaddriver

    quaddriver 120 What's per channel Subscriber

    I think it does, so if I fix the bad 200 ohm pot so it is back in range, I can get her near the 45ma. its a scary number for a pioneer guy, but who am I to question kenwood. thanks!
     

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