Cyber blowing F1 fuse on power-up

I have a Cyber that instantly blows fuse F1 when the unit is switched on.

Tried a different power factor cap - same thing. Swapped the PSU board with a working unit and the problem followed the PSU board. Also tried powering-up without a lamp - no difference.

So am assuming the problem lies somewhere on the PSU board.

Any suggestions as to likely faulty components?

Thanks,

Scotty.
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  • 0
    F1 feeds the fixture power transformer, so if the 28V motor supply is shorted, it may well take out that fuse, since that supply does not appear to be fused on the secondary side . . .

    No lamp power runs in F1, so the P Factor cap and lamp will not be involved . . . D9 and D10 on the power board are a half of a full wave rectifier pair of the 28V AC power from the transformer, complementing the two SCRs that are the "heart" of the 24V switching supply, and if either faults in a short, it will ground that supply . . . which could well take out F1. Do you ever see any motor movement, or signs of life on the 24V DC rail? D9 and D10 are in the input to that supply, so if they fail, all motor power will go away as well . . . .

    - Tim
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  • 0
    F1 feeds the fixture power transformer, so if the 28V motor supply is shorted, it may well take out that fuse, since that supply does not appear to be fused on the secondary side . . .

    No lamp power runs in F1, so the P Factor cap and lamp will not be involved . . . D9 and D10 on the power board are a half of a full wave rectifier pair of the 28V AC power from the transformer, complementing the two SCRs that are the "heart" of the 24V switching supply, and if either faults in a short, it will ground that supply . . . which could well take out F1. Do you ever see any motor movement, or signs of life on the 24V DC rail? D9 and D10 are in the input to that supply, so if they fail, all motor power will go away as well . . . .

    - Tim
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