Fisher 500, how much can they be improved

Discussion in 'Fisher' started by Sam08861, Jun 11, 2018.

  1. thornev

    thornev Active Member

    Messages:
    368
    Location:
    Mid Hudson Valley, NY
    Good suggestion rider. If I go forward with "take 3", I'll add that picture too.
     

     

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  2. thornev

    thornev Active Member

    Messages:
    368
    Location:
    Mid Hudson Valley, NY
    Here is the underside of the Unity Gain board I built with annotations. If you view this image along with the images in post 12 and the thread referred to in that post, maybe someone can tell me what I've done wrong to cause distortion when I installed the board into my 500-C.

    Note that there are a few places marked "GROUND". They are all connected via the grey wire that runs vertically on the underside of the board.

    I apologize for the scribbling mess. My editing program doesn't allow me to go back in time to erase stuff (I can erase only the LAST edit). I had a hard time figuring out how to represent the fact that some components are connected in parallel such that the non-ground leads are connected to each other. They are not connected to a single wire that runs across the board as it does on the schematic.

    I will post a picture of how I wired the board the next time I open the receiver. It's fairly easy to describe. I disconnected the wires from the 2 center posts on the volume control. Then I took the LEFT IN and RIGHT IN wires from the board and connected them to the center tabs. I connected the wires I disconnected from the center tabs to the LEFT OUT and RIGHT OUT leads coming from the board. The diode lead from the board was connected to the same place at which I connected the IBAM board to get current - pin 4 of V14 which is where the SDS Labs board filament wire is connected i.e. the B- (I think). The ground lead from the board was connected to the same ground I used for the IBAM board which I think is just a lug on one of the terminal boards on the chassis. I tested with a DMM to ensure there was continuity between bare metal on the chassis and the ground on the board.

    UPDATE Jun 16... I've added the annotated TOP of the board so one doesn't have to go to an earlier post, back and forth, to match components.
     

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    Last edited: Jun 16, 2018 at 11:12 PM
  3. Sam08861

    Sam08861 Active Member

    Messages:
    349
    Location:
    Northwestern NJ
    When the weather gets worse or we get a rainy weekend and I'm not compelled to be on my boat, I'll start my build. Hopefully you'll get it figured out by then :)

    If not, I'll post as I go and we'll see if we can't get this to work.
     
  4. thornev

    thornev Active Member

    Messages:
    368
    Location:
    Mid Hudson Valley, NY
    Thanks, Sam. In the meantime, I'm going to try a variety of tasks to see if I can figure it out. Thorne
     

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