FM 200B - What am I missing? (part) and Jewel recommendation

Discussion in 'Fisher' started by rufleruf, Mar 16, 2017.

  1. rufleruf

    rufleruf AK Subscriber Subscriber

    Messages:
    703
    Dave - here are backed up pictures - you can just see the disconnected relay wire.

    [​IMG]

    [​IMG]
     
  2. dcgillespie

    dcgillespie Fisher SA-100 Clone Subscriber

    Messages:
    8,253
    Location:
    Ball Ground, GA
    It's hard to tell your absolute connections on the rear of the switch due to the depth provided in the pic, but ultimately, they should connect this way:

    1. The 560K resistor goes to the "top" terminal of the control (terminal closest to the bottom plate). That is the only connection to that terminal.

    2. The 470K resistor goes to the wiper terminal of the control. That is the only connection to that terminal.

    3. The bare wire from the T-strip ground terminal comes over to one switch terminal, from there over to the "bottom" terminal of the control (closest to the chassis floor), and from there to the lose lead from the relay.

    4. The other switch terminal associated with the grounded switch terminal connects to the black lead going over to the nearby 15 Ohm resistor on the lamp array (the inclusion of the 15 Ohm resistor is a modification by someone, not Fisher).

    5. The other two related switch terminals have the 330K on one terminal, and the black lead going over to the muting oscillator coil on the other.

    I hope that helps!

    Dave
     
  3. rufleruf

    rufleruf AK Subscriber Subscriber

    Messages:
    703
    Dave - thanks for the instructions. I got it all hooked up. Passed DBT so I plugged it into the KX100 I've been cleaning up. It powers up and plays, but mono plays through one channel and if I switch it stereo the other. I think mono is left, but I haven't verified all connections are correct. AFC light comes on, muting does not seem to work. I plan on testing all tubes and cleaning pots and sockets before I go any further.

    I suppose the .1uf brown caps in these are suspect, and the electrolytics are assumed to be out of spec if not totally dead?
     
  4. dcgillespie

    dcgillespie Fisher SA-100 Clone Subscriber

    Messages:
    8,253
    Location:
    Ball Ground, GA
    Certainly replace any small electrolytic caps, as well as the power supply cap, and change the rectifier to silicon using a 100 Ohm dropping resistor as I've described before. The film caps can be replaced, but are at the low end of your to do list.

    Clean the relay contacts, and that may resolve your sound issue from both channels.

    Make sure that your switch leads on the muting control are correct -- that you don't have the leads crossed between the two separate switches. That's why I gave the detailed instructions for their connections. Use your Ohmmeter to verify which two terminals go together for the two separate switches within the muting switch.

    Dave
     
  5. rufleruf

    rufleruf AK Subscriber Subscriber

    Messages:
    703
    I've got a Mouser order coming for jewels and electrolytics. Two of the tubes were bad, and the pots all need cleaning (of course I forgot to order deoxit), so I have some house keeping to do before I move forward on it. Need to look up "stereo relay contact cleaning" on google. And then there is the likelihood of MPX adjustment being needed... and my Hickok 752 is currently out of commission...

    I may dig into the FM100B while this one is in holding pattern. Right now my pile of restored ones is quite a bit smaller than my pile of projects.
     
  6. larryderouin

    larryderouin Do I get Food, Med's, or more gear this Month? Subscriber

    Messages:
    18,153
    Location:
    Glen Burnie Md.
    Matt; Cut some paper strips sized so they will fit in between the contacts. Drizzle some Deoxit on them, then insert to one end and pull thru to the other end. Discard that paper and keep doing the same about 5-10 times on the contacts (held closed) until the paper comes out clean. 1 pass on each paper. Don't go back and forth on the paper.

    Larry
     

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