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YBA-1 clone Lifco model 1000 cap job

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  • YBA-1 clone Lifco model 1000 cap job

    So i just started restoring my lifco model 1000 (YBA-1 clone) and i noticed something rather strange. There's this blue mallory electrolytic flapping in the breeze that started leaking. Assuming the amp is a clone of the YBA-1, this cap is 450V 80 uF and should be connected between the 2 paralleled 40uF can cap sections and B+. It is labeled C23 on the YBA-1 schematic I don't know if you can see it on the picture but it seems to be wired backwards. Its positive lead is wired to the can cap positive pin and the negative lead goes to the standby switch... Even so, the amp runs ok with a little bit of 340hz noise. I find it strange that the cap haven't exploded yet! I have a brand new f&t 500v 50 uF that i want to put in it's place but i want to make sure i'll install it correctly...


    Click image for larger version

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  • #2
    It does appear to be backwards.

    The schematic is not clear on the polarity.

    YBA1 Original.pdf

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    • #3
      It's impossible for us to tell where it is going from the picture, so triple check. But yes, the pos. end should go to standby switch, and the neg. end should connect to the can cap pos. pin.
      Those 16V caps in the bias circuit didn't blow up either, so who knows what the deal is .
      Originally posted by Enzo
      I have a sign in my shop that says, "Never think up reasons not to check something."


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      • #4
        Odd that it hasn't popped yet. I just picked up a '71 a week ago. It appears to be mostly stock (one cap change and 1 ohm resistors added to the tube sockets to check bias). I'm waiting on parts so I haven't touched it yet. Here's a shot of the board if it helps.

        Click image for larger version

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        It's a ripper too. Les Paul straight in.

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        • #5
          Looks like one of the wires may be coming off at the phase splitter socket?
          Originally posted by Enzo
          I have a sign in my shop that says, "Never think up reasons not to check something."


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