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X-202 restoration

Discussion in 'Fisher' started by JEM@Clem, Dec 13, 2017.

  1. JEM@Clem

    JEM@Clem New Member

    Messages:
    13
    Location:
    Clemson, SC
    Your right gadget. Looking at the schematic 2 of the cans are common negative and one is common positive.
     

     

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  2. gadget73

    gadget73 junk junkie Subscriber

    Messages:
    36,556
    Location:
    Southern NJ
    The common positive is probably bias supply then. Usually lower voltage than the others as well. Just make sure you mind the polarity when rebuilding or replacing that one, it goes badly otherwise.
     
  3. JEM@Clem

    JEM@Clem New Member

    Messages:
    13
    Location:
    Clemson, SC
    Reading around the forum, it looks like the easiest modification I can make to help keep the tubes alive longer is putting a CL-80 current inrush limiter on the ac power supply, like Dave did in his "Gilding the X-202B" thread.
    When I put this in, it should go between the power switch and the ac in line, correct? And while I'm thinking about the power switch, the master volume potentiometer with the power switch built in appears to have kicked the bucket long ago. Any suggestions on where to find a new one?
     
  4. notdigital

    notdigital AK Subscriber Subscriber

    Messages:
    2,237
    Location:
    NYNY
    The primary purpose of the current limiter is to protect the on/off switch which is a historically proven weak spot across all fisher instruments. It slowly allows the ramp up of current from your wall to the unit. Secondarily, due to resistance, it drops the voltage to the unit slightly which helps it "see" voltage that is closer to what the designers were exposed to back in the day. The CL-80 only indirectly helps affect tube longevity and only to a negligible degree.

    If you look at Dave's restoration in his "gilded" version, he put it on an existing terminal strip. I put mine in at a different location. When all is said and done, it does go "between" the AC line and the switch but where in that circuit would depend on you. I chose the location in mine because I flipped resistors on the terminal strip where Dave put his CL-80 so there wasn't room, and the spot that I eventually chose had vent holes above. In the end it depends on your own design eye.

    As far as the power switch is concerned, I may be able to help you but that conversation would have to take place privately.

    [​IMG]
     
  5. JEM@Clem

    JEM@Clem New Member

    Messages:
    13
    Location:
    Clemson, SC
    Currently I'm looking at replacing all the electrolytic caps and adding a current inrush limiter. here's my parts list:
    1. original: 50uF@3V
      1. replacement: 50uF@6V
    2. 40@500
      1. 40@600
    3. 20@250
      1. 22@350
    4. 40@450
      1. 40@450
    5. 40@400
      1. 40@450
    6. 20@300
      1. 22@350
    7. 20@250
      1. 22@350
    8. 1000@35
      1. 1000@35
    9. 50@70
      1. 50@100
    one that i'm unsure about is replacing my cardboard covered cap can (200uF@250V) with one of equal value, but labeled 250VAC (https://www.amazon.com/TOOGOO-200MFD-Terminal-Starting-Capacitor/dp/B00SUXOAT6)
    I think the original voltages were given in DC voltage, so this part shouldn't work. If this won't work, where can I look for one that will?
     
  6. dcgillespie

    dcgillespie Fisher SA-100 Clone Subscriber

    Messages:
    9,673
    Location:
    Ball Ground, GA
    One option is to get this can from Antique Electronic Supply: www.tubesandmore.com/products/capacitor-ce-mfg-350v-50505050uf

    Strap all four sections together making it a 200 uF cap at 350 vdc. Remove the cardboard cover from the old cap, and install it over the new cap using an appropriate adhesive to secure it.

    I hope this helps!

    Dave
     

     

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  7. JEM@Clem

    JEM@Clem New Member

    Messages:
    13
    Location:
    Clemson, SC
    I finally got parts in, and now I'm wondering how to get the cardboard off of the cap
     
  8. JEM@Clem

    JEM@Clem New Member

    Messages:
    13
    Location:
    Clemson, SC
    Also I found an inconsistency between the parts list and the schematic. 20uf vs. 200uf
    parts list.PNG
    schematic.PNG
    Guess who bought the wrong one.
     
  9. gadget73

    gadget73 junk junkie Subscriber

    Messages:
    36,556
    Location:
    Southern NJ
    I go by whats in the unit vs what the schematic says when possible.
     
  10. nj pheonix

    nj pheonix AK Subscriber Subscriber

    Messages:
    9,825
    Location:
    New Jersey
    If it makes you feel any better, we've all ordered the wrong thing one time or another.
     
  11. Catmanboo

    Catmanboo AK Subscriber Subscriber

    Messages:
    483
    Location:
    Atwater, ohio
    Try a hair drier to get the sleeve off. Heat should soften the adhesive, usually a dab of tar or some such. Twist gently.
    Had to do this once to get info stamped on the can. Ya'd think they would've marked the cardboard sleeve, but-noooo! And schematics sometimes have typo's & other discrepancies. If it says something other than what's on the part at hand, provided it's an oem part, go with what the part says.
     

     

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  12. gadget73

    gadget73 junk junkie Subscriber

    Messages:
    36,556
    Location:
    Southern NJ
    I've always ordered the right part, just sometimes its for the wrong project and it takes years to obtain the correct one :) Took me almost 10 years to buy the Continental to make use of the antenna mast I'd bought. Also possible I bought it to make use of the AC evaporator core I bought like 4 years ago. I hope it is, I don't feel like having to buy something to install that in.
     
    larryderouin and nj pheonix like this.
  13. JEM@Clem

    JEM@Clem New Member

    Messages:
    13
    Location:
    Clemson, SC
    I finally finished recapping my X202, and I'm itching to power it on. I have a couple questions though.
    First, I'm running with 2 speakers, no center. Do I need to put a resistor etween the center taps, or can I just turn the center speaker knob to OFF?
    Second, The speakers I have available are Pioneer CS-G303. 120W 6 OHMS. After I fond these I realized the Fisher doesn't have a 6 Ohm output, only 4, 8, and 16 Ohm. What Do I Do??
     
  14. Todd Dodds

    Todd Dodds AK Subscriber Subscriber

    Messages:
    1,548
    Location:
    South of Asheville NC
    DON'T TAKE MY WORD FOR THIS!!!!....
    ********************************************

    I've got two x202's that DGillespie did, with his mods, so some terminals may well be different from your work. Both units have only a jumper from the right channel 8ohm terminal to "S" terminal..
    Center channel switch is off.
    Your 6ohm speakers should be fine on the 8ohm positions.
    When you turn it on, the center red jewel will light, but only faintly. It goes to full brilliance in the on position.

    But wait for someone a little smarter to confirm....I've blown up a lot of stuff.

    Edit: Just realized you have a X202-B, rather than a 202...so ignore all the above blather.
     
    Last edited: Jul 15, 2018
  15. larryderouin

    larryderouin Turn it UP, POP? PLLUUEEEZZZZZEE Subscriber

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    21,791
    Location:
    Glen Burnie Md.
  16. JEM@Clem

    JEM@Clem New Member

    Messages:
    13
    Location:
    Clemson, SC
    So I got everything hooked up and started it up. I only got sound out of the right speaker. It sounded good, but then it stopped :(
     

     

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  17. JEM@Clem

    JEM@Clem New Member

    Messages:
    13
    Location:
    Clemson, SC
    I finally got some DeOxit in, and I cleaned every pot, switch, and port on the amp.
    After hooking it up I started it and it was really quiet, then the volume jumped rapidly. Kinda scared me, but nothing blew and it stayed at that volume. Then I noticed I was only getting sound out of the right channel. I turned it off and swapped speaker inputs. Sound kept coming out of the right channel. The sound I was getting was beautiful, but I read that the left channel is the Fischer's "primary" output, so I turned it off again.
    Any advice, thoughts, or speculations on the silent left channel??
     
  18. Tim D

    Tim D AK Subscriber Subscriber

    Messages:
    1,237
    Location:
    Melbourne, FL
    I would have brought it up on a dim bulb tester (DBT) or slowly on a variac and measured voltages thoughout the unit with speakers hooked up first. Having the (approximately) correct voltages as marked on the schematic goes a long way to determining initial problems. After that you can check that all the tube pins are making contact and you could re-tension the sockets with a dental pick (with it turned off of course). Make sure all the tubes are heating for both channels. Have you had all the tubes tested? Since you have a working right channel you can use that as your working example and focus on problems in the left channel path. I would do the checking with a variac or DBT while powering it to reduce the chance you could be damaging something if you have a short or something is installed wrong.

    If your left channel is completely dead you might check the voltages on the output tube plates to see if you are open-circuited in the left output transformer. It's a stretch as I'm guessing the X-202-B is a push pull and it would require both legs of the primary to be open or the secondaries to be open to make the channel completely dead. That's probably not very likely, but it could happen. I had a bad primary leg in the output trannie on one channel on my KX-100, but it was still working - albeit with reduced volume because only one tube was working on that channel.

    Be careful of the high voltages and ask for help from someone who knows if you feel you can't be safe around the high voltages.
     

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