HF-81: How to remove power switch?

Discussion in 'Eico Place' started by ssouci, Apr 18, 2017.

  1. ssouci

    ssouci Well-Known Member

    Messages:
    551
    Location:
    Vancouver, BC, CANADA
    is it possible to completely remove power switch mounted on the back of the treble pot assembly on an Eico HF-81?

    how do I do it please?... do I have to remove (and unsolder) the assembly first to gain access to it, or can I do it with the pot assembly in place?

    the reason I'm asking is that one "channel" of my treble adjustment controls will not rotate past 3 o'clock (whereas the other one will go all the way to maximum at 5 o'clock)... about once in 100 tries, it does rotate all the way, but usually not...something is mechanically and very solidly stopping it

    I suspect that something has gone mechanically awry inside the switch unit, and this is blocking the rotation of the shaft and hence that potentiometer (because they share the same shaft)

    note: I am no longer using the power switch, so would be happy to have it completely gone

    thank you!
     

    Attached Files:

     

    Please register to disable this ad.

  2. tube-a-lou

    tube-a-lou Super Member

    Messages:
    4,418
    I've done it, first you have to find a centralab potentiometer, because you need the rear cover of that.
    then you have to remove the whole assembly from the amp and take it apart, once you get down to
    the last section you could pop out the switch and replace the back with the new rear cover, sometimes
    you have to Dremel like I did a space for the ground on the rear of the pot but it came out good and no
    more switch. I'll add a picture of mine.
     
  3. ssouci

    ssouci Well-Known Member

    Messages:
    551
    Location:
    Vancouver, BC, CANADA
    thanks... sounds like a lot of work, especially since all the connecting wires need to be desoldered and resoldered (!!!)

    it's been suggested to me that I can maybe just pry the switch off by sticking a knife blade in between (the rear pot and the switch housing), and then gradually working the switch assembly off... it might be held on by 3 internal tabs(?)... no way?

    thanks
     
  4. tube-a-lou

    tube-a-lou Super Member

    Messages:
    4,418
    Their right, tabs on the inside be careful!
     
  5. ssouci

    ssouci Well-Known Member

    Messages:
    551
    Location:
    Vancouver, BC, CANADA
    thanks... and if you ever get the chance, would be great to see a photo of yours
     
  6. tubeactive

    tubeactive AK Subscriber Subscriber

    Messages:
    65
    Location:
    NJ
    Actually, rerouting some of the AC wiring away from the circuitry, closer to the power tranny and rear chassis edges, could be beneficial and lower the noise floor. Many HF-81 and HF-85 users install a power switch on the rear.
     

     

    Please register to disable this ad.

  7. ssouci

    ssouci Well-Known Member

    Messages:
    551
    Location:
    Vancouver, BC, CANADA
    in my case, the unused "tape selector" switch on the front panel has been converted to the on/off switch... very neat

    and in my case it's not that the stock switch does not work (it's not even connected anymore), but rather that it was left behind and I think it's physically broken inside and impeding the full rotation of the treble pot on one channel (which is on the same shaft)... I would like to get my full rotation back
     

Share This Page