Fisher TX55 restoration

Discussion in 'Fisher' started by paul_ral, Apr 20, 2018.

  1. paul_ral

    paul_ral Active Member

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    Found the TX55 in defective condition, I am waiting for pick up. I think is rare, this is reason why I bought it.
     

     

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  2. paul_ral

    paul_ral Active Member

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    Which tuner is a good match for TX-55?
     
  3. paul_ral

    paul_ral Active Member

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    212
    Picked up my Fisher today, so it has a painted wood case, no original knobs (I pus some Marantz ones), a lot dirt inside. The front panel is in good condition
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    Before
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    After a good bath
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    Powered on, no AC voltages after transformer. Check the voltage after power switch no voltage again. So I put another power switch and amplifier runs. I repaired OEM switch and installed inside. I check DC output voltages and BIAS, all are OK. With speakers connected the right channel is weak. I plan to do a total recap.
     
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  4. rufleruf

    rufleruf AK Subscriber Subscriber

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    A handsome unit! I think this may have replaced the TX2000, or more probably the TX50 in the line up.
     
    Last edited: Apr 23, 2018
  5. paul_ral

    paul_ral Active Member

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    212
    PS board before
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    Some parts are gone: 2000uF filter capacitor and G1 rectifier diodes.
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    New parts: fast diodes UF5405 and 2200uF/63V United Chemi-con 661-ESMH630VNN222MQ2
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    It looks better now!
     
  6. fred soop

    fred soop Super Member

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    Check the diodes for heat after operating for a while. The old ones were mounted spaced away from the board. Sometimes this is done for heat dissipation.
     

     

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  7. paul_ral

    paul_ral Active Member

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    Thanks!
     
  8. larryderouin

    larryderouin Turn it UP, POP? PLLUUEEEZZZZZEE Subscriber

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    Fred beat me to it. I make a habit of raising them 1/4" off the board for airflow. If you've ever seen a fried PIONEER SX-1010 power supply board you'll understand why.
     
  9. paul_ral

    paul_ral Active Member

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    I'll raise them. That Pioneer has 100W per channel vs arround 20W so it is a big difference in power consumption of course.
     
  10. larryderouin

    larryderouin Turn it UP, POP? PLLUUEEEZZZZZEE Subscriber

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    The SX-1010 also has the POWER SUPPLY on the bottom of the unit and the board is Upside down, and has little to no natural ventilation either, due to the design of the unit. So the heat from the P.S. gets trapped and pretty soon stuff starts overheating and boards get brittle. The boards can be re-populated, even totally black boards as long as the traces are in decent condition, and best practice now is to raise diodes off the board, along with power resistors (which incidently do more damage to the board than the diodes). There is even a special tool to put a crimp in the leads so they stay up away from the boards while you are positioning and soldering.

    I would replace the rest of the caps on the power supply at minimum. Once the voltages are stable and reliable, the rest of the unit should follow suit.
     
  11. paul_ral

    paul_ral Active Member

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    212
    Thanks for reply Larry.
    The power source is very simple as you can see: 1 filter cap, 4 diodes and 1 resistor. I am planning to do a total recap and I placed my order to Mouser. Most of capacitors are Nichicon KL in signal path, Nichicon KA for the others and KG for coupling. I used KA series in my SX-440 and I like how it sounds. These caps are smaller so I have well-ventilated boards inside. I'll change all carbon resistors with Dale ones too.
     
    Last edited: Apr 25, 2018

     

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  12. paul_ral

    paul_ral Active Member

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    I can use some ceramic spacers around leads as I used in my restored Kenwood KR-3130
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  13. paul_ral

    paul_ral Active Member

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    Big dilemma: which caps should I choose?
    Mundorf
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    or Nichicon KG
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  14. larryderouin

    larryderouin Turn it UP, POP? PLLUUEEEZZZZZEE Subscriber

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    I'd go with the KG's as they tend to work best with other Nichicon's. But if they're too tall, go with the Mundorf's.
     
  15. paul_ral

    paul_ral Active Member

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    212
    Thank for advice. I'll go with Mundorf and keep the KG for my Marantz model 29 recap.
     
  16. paul_ral

    paul_ral Active Member

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    212
    Today my order came from Mouser and I finished my amplifier. Some pictures with final result:
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    For amp section I use Nichicon KL and Nichicon KA series and Mundorf M-Lytic for outputs. All carbon resistors were replaced with Vishay/Dale new ones. I replaced old mica with silicone pad on outputs transistors.
    In preamp section I use Elna Silmic II, Nichicon KL, Nichicon KA and Nichicon ES caps and I keep all transistors on boards.
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    Adjust DC balance potentiometer VR601 and VR603 for equal clipping and set BIAS from VR602&VR604 to obtain 7,5mV across R614 and 612. Both channels works great, no hum, so I am thinking to keep all low signal transistors on boards.
    Thanks for watching!
     

     

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  17. paul_ral

    paul_ral Active Member

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    Old parts
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  18. larryderouin

    larryderouin Turn it UP, POP? PLLUUEEEZZZZZEE Subscriber

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    Nicely Done. How does it sound???
     
  19. paul_ral

    paul_ral Active Member

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    For me it sounds warm but it is a little difference between Pioneer SX-440 and TX-55, Pioneer has more bass at low volume. Increasing the volume the bass become more present, like my Marantz 1060 works. Overall I like how it sounds. Maybe because I recapped my old Sansui SP-70 using the capacitors which you recommended to me. Thanks again
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    Next step is to order 6 knobs from Mouser, I found these:
    https://ro.mouser.com/ProductDetail/450-2225
    https://ro.mouser.com/ProductDetail/450-2225
    Then I'll send the wood cabinet to the carpenter because it was painted in black.
     
  20. larryderouin

    larryderouin Turn it UP, POP? PLLUUEEEZZZZZEE Subscriber

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    Sounds like a plan both for the knobs and the speakers.
     

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