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Yamaha C4 Preamp Recap Question

Discussion in 'Yamaha' started by jdawg, Apr 19, 2017.

  1. jdawg

    jdawg New Member

    Messages:
    21
    I have a Yamaha C4 preamp that I would like to recap. I have the service manual and will be making a list of all the electrolytic capacitors that I need to purchase. I will be ordering from Digikey or Mouser but the problem is I'm not sure what type of capacitors I should choose. Does anyone have recommendations on which capacitors I should be ordering?
     
  2. Mr. Yamaha

    Mr. Yamaha With a hint of Kenwood Subscriber

    Messages:
    464
    Location:
    Haarlem, The Netherlands
    I used Elna Silmic II for signal path caps, Nichicon ES for bipolar caps and Nichicon PW for the other caps. Assuming we are solely talking about the electrolytics.

    I also advice you to replace all VD1212 varisors with 2x 1N4148 diodes in series and all 2SC458 transistors with KSC1845FTA's.
     
  3. jdawg

    jdawg New Member

    Messages:
    21
    Thanks for the suggestions. I did not even consider replacing the VD1212 or 2SC458 transistors but will replace those as well. I think those are also the same transistors I had to replace in my Akai reel to reel deck. Now the hard part is to figure out which capacitors are in the signal path so I know which Elna capacitors to order.
     
  4. Mr. Yamaha

    Mr. Yamaha With a hint of Kenwood Subscriber

    Messages:
    464
    Location:
    Haarlem, The Netherlands
    For the bi-polar (BP) signal path caps you can use also Nichicon ES (same as for non signal path BP).

    C121
    C122
    C123
    C124
    C125
    C126
    C127
    C128
    C163 BP
    C164 BP
    C177 BP
    C178 BP
    C309 BP
    C310 BP
    C503 BP
    C504 BP
    C511
    C512
     
  5. jdawg

    jdawg New Member

    Messages:
    21
    Thanks for the list of capacitors that are in the signal path. It saved me a lot of trouble as I was having difficulty reading the schematic and figuring out the path of the audio signal.
     
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  6. Blue Shadow

    Blue Shadow I gotta get me a new title

    Messages:
    17,234
    Location:
    SE PA
    I'm taking my huge scat and marking all those caps. Maybe I can learn something new from that exercise.
     
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  7. Edu1985

    Edu1985 New Member

    Messages:
    18
    Blue shadow how did it work out the recap?i m thinking about recaping too.and how much did you pay for the caps?and how about the difference in sound?Mr.Yamaha that capacitors list includes the phono stage mm??
     
  8. Blue Shadow

    Blue Shadow I gotta get me a new title

    Messages:
    17,234
    Location:
    SE PA
    I used mostly UFW Nichicon, one of their audio caps. Why did I use audio caps, well because Nichicon has decided to market them as audio caps and there must be something to that because they look better than the turd brown caps other lines are covered with and I did see that Sony used Nichicon Audio caps in their top of the line ES 5.1 receiver or whatever is laying dead in my entrance foyer. If Nichicon and Sony think there is something to it, I do not care what any AKer that is not a modern electrical audio equipment designer or a current capacitor engineer at a major capacitor manufacturer says. That cost me an extra few bucks but I believe the total of all the new crap I threw into the unit is under 50 bucks. C-4 as is working, 200 worth, recapped, maybe 400 worth, time to install all those parts...who cares it is a hobby and I like my new soldering iron. Taking time: cleaning the switches, wrestling with the function controls, still not part of the equation. Then the multiple hours of removing the slider switches, the long ones between the function switches, time I will not get paid for when I sell the unit, if that were to happen. I have three tts it has three tt inputs. I need more high level inputs but I have a switch box for that.

    As to sound quality, this unit was picked up with some Crown amps, a JVC tt, Onkyo tuner and full Dahlquist DQ-10 system with one sub and electronic crossover which is what I wanted at that time. I didn't really use the C4 before a recap and then had trouble with it missing a channel that Dave explained how to fix, clean the long phono loading control switches on the board. Although the preamp is in the main rig right now, I haven't gotten serious about comparing it to the preamps that are usually there because of the dropped channels that happened when installed prior to that fix as well as a dropped channel in a turntable with one specific cartridge. I hope all these channel issues are resolved. I do have other cartridges but this one has no wear.

    I probably need to leave it in the rig until I learn all the controls because I can't read that fine white writing on the black faceplate in the dimly lit room. Think I'll do that, thanks for making me think about this preamp.

    Caps, transistors, variable resistors, diodes, resoldering, cleaning, removing and cleaning. Quite a bit of work but none of it hard or expensive. Results are worth it. I don't like having gear that doesn't sound good in my system. Took me less than an hour to replace a bad sounding tube unit that I replaced the coupling caps in when it was breaking in. It sounded like crap the first two times I plugged it in and had to leave the house while it did the break in over a few hours.

    Go for it.
     

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