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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:
    866
    Dragged home a bunch of Fisher projects today. I thought this FM200B was the worst of the lot besides the 500B that was dropped hard and has a mystery volume pot; but it cleaned up pretty nice. Problem is - it's missing the AFC rotary 4 position switch. Anyone care to open up their FM200B and show me what's missing? Maybe I can hotwire it to be in the most likely to be useful position and glue a knob right to the faceplate.

    Also, anyone have any opinion of the current crop of faceplate jewels on ebay?

    This and my X202B could be so happy together...

    [​IMG]

    [​IMG]
     
  2. notdigital

    notdigital AK Subscriber Subscriber

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    My tuner is presently out getting "tuned up" but some pics I took when I worked on it may help, below.

    If by the auction jewels you mean the original faceted ones with the mounting stub: those are factory pieces. The seller is asking for $$$ that I would never fork over. Some other auction jewels are available at Mouser for pennies. Plug in this number for an example: 593-2000A. Lastly, there is an auction seller with faceted jewels that you have to glue on. Those look closest to the original but you have to glue them on as there is no stub. Too pricey for me still. I guess you decide where you want to spend your money. I bought the Mouser pieces for my X-202-B. Never had a second thought.

    Here's a thread with pics of two of the jewels mentioned above:

    http://audiokarma.org/forums/index.php?threads/replaced-the-jewels-on-my-x-202-b.545519/
     

    Attached Files:

    Last edited: Mar 16, 2017
  3. dcgillespie

    dcgillespie Fisher SA-100 Clone Subscriber

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    Ruf - What you are showing as missing is the Muting control. It is a standard size 100K control with linear taper, with a DPST rotary switch, similar to those used for the power switch in Fisher receivers.

    Dave
     
    Last edited: Mar 16, 2017
  4. rufleruf

    rufleruf AK Subscriber Subscriber

    Messages:
    866
    Well golly - I found just such a pot/switch in a box of miscellany, I wonder why it was removed?
     
  5. dcgillespie

    dcgillespie Fisher SA-100 Clone Subscriber

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    Often times, its due to the switch.......

    Dave
     
  6. notdigital

    notdigital AK Subscriber Subscriber

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    Yeah, when I got my tuner, that switch was shot. Prior owner probably tossed the whole thing without realizing that the switch itself could be replaced/repaired. The pot itself was probably still good.
     
  7. rufleruf

    rufleruf AK Subscriber Subscriber

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    Huh. I have some of these switches on misc pots from console preamps I've purchased on ebay over the last decade - I'll give swapping the switch out a go following the rebuild sticky above as a guide.

    Fisher haul came with a 100B as well, and I see a 100K pot with the same R50160 part number but a different dash number. I wonder if this has the switch? Of course the 100B is not in too bad shape, so it ought to be made to work too I suppose.
     
  8. notdigital

    notdigital AK Subscriber Subscriber

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  9. rufleruf

    rufleruf AK Subscriber Subscriber

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    If I read the Jewels thread right, the jewels from Mouser are the same snap in ones sold on eBay?
     
  10. Patrice B

    Patrice B AK Subscriber Subscriber

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    For the jewels: I bought some replicas on the Bay, no glue, just push and fit. Plastic ones, cheap. Probably similar at Mouser.
     
  11. dcgillespie

    dcgillespie Fisher SA-100 Clone Subscriber

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    Both the 100B and the 200B have the muting feature, with the front panel control that both turns the feature on and off, and also sets the threshold as to the signal strength level at which the muting function begins. However, regarding this control, the 100B employs a simple SPST switch for the muting function, as all the switch does in that unit is turn the power on and off to the muting oscillator circuit. However, in the 200B, the switch is of the DPST type, since the switch not only turns the power on and off to the muting oscillator, but also controls the power to the front panel muting indicator lamp. These are two different power sources as the power for the muting oscillator is B+ voltage, while power for the indicator lamp is from the 6.3 volt heater winding of the power transformer. Sometimes you get lucky and find that the switch in a 100B is of the DPST type with half of the switch unused. Most of the units I've seen however just come with a SPST switch, since that is all that's required for that unit. It just depends on what Fisher was sourcing at the time of production. The bottom line however, is that a good switch from a 200B will always work in the 100B, but a good switch in a 100B may, or may not work in a 200B.

    Dave
     
  12. rufleruf

    rufleruf AK Subscriber Subscriber

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    So DPST completes two separate circuits when switched on? Had never given this much thought. I'm sitting here with 20 odd used potentiometers with switches trying to find a combo, and I was thinking I was looking for a one in, three out, but really it's two each one in, one out switches in one - hence the name. And I suppose the little bridging bit on the receivers on/off switches is to have one in work for two outs?

    Just opened the 100B - the switch is a DPST. Might have to do a larger swap to utilize a SPST NOS switch I just found and have a spare DPST for a receiver on - off or other.

    Almost there...
     
  13. gadget73

    gadget73 AK Subscriber Subscriber

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    The power switch on the receivers sort-of had two in and two out, or more accurately two one in, one out switches. Both inputs are strapped together and tied to the power line coming in. One output went to the power transformer, the other went to the outlets on the back of the unit. Strapping the two together makes both sets of contacts carry the load of the transformer plus whatever you plug in to the outlets. If you don't use the outlets on the back, that means both sets of contacts are each carrying half of the unit's load rather than one doing nothing and the other doing all the work.
     
  14. rufleruf

    rufleruf AK Subscriber Subscriber

    Messages:
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    Here are the pictures.

    First shows the new switch components and the pot in the foreground, originals in the middle, and a bunch of not-quites in the back ground.

    Second is the switch as assembled.

    Third is after continuity testing. Now I just have to trace the diagram for a while.

    [​IMG]

    [​IMG]

    [​IMG]
     
  15. rufleruf

    rufleruf AK Subscriber Subscriber

    Messages:
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    What is the wire coming out of the relay seen here? I'm not sure what's going on in the schematic - kind of looks like it might go to the pot? Schematic I have is for 30000 on and my unit is 21199. On the 100B it goes to the middle pot leg.

    Also need to know what knob types are correct? I assume tuning knobs are without pointers and skirts, the four function knobs have pointers but no skirts?

    [​IMG]
     
    Last edited: Mar 16, 2017
  16. dcgillespie

    dcgillespie Fisher SA-100 Clone Subscriber

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    You have an older version that uses a relay to accomplish the stereo/mono switching, whereas the newer version uses a diode matrix circuit to accomplish that. A wider pic will help.

    Dave
     
  17. larryderouin

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

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    2nd pic in post 2 (notdigital's) has the relay next to the muting control. If you blow it up you should be able to make out all the wiring.
     
  18. notdigital

    notdigital AK Subscriber Subscriber

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    Well, while the one guy at auction represents that his jewels have been "custom made to fit," no such claim is made by Mouser. Mouser's non-custom jewels come in at around 50 cents a pop; auction jewels come it at around $5 a pop. Other than looking and functioning EXACTLY alike, they're different, I guess :rolleyes:
     
  19. larryderouin

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

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    One has E-Screwed and the other has Mouser printed in extremely fine print on the ends. I'm betting the MarOOn on Ebay is getting his from Mouser and taking the markup as profit!
     
  20. gadget73

    gadget73 AK Subscriber Subscriber

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    possible he's sanding down part of it to reduce size in some dimension. Likely nothing you couldn't do yourself.
     

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