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Thread: Roland cube 20 old version 117v

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    Roland cube 20 old version 117v

    Hello got an old 117v cube. Tx is toast after being plugged into 230v
    Click image for larger version. 

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    Looking at getting a replacement.
    Not sure on the current rating.
    Maths not my thing 😃
    Any assistance from you wizards will be grateful

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    Supporting Member Randall's Avatar
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    If it was plugged into 230v, there is probably more wrong with it than just the PT.

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    It's weird, because it WAS working fine.....

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    Senior Member nevetslab's Avatar
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    Quote Originally Posted by Arbutt View Post
    Hello got an old 117v cube. Tx is toast after being plugged into 230v
    Click image for larger version. 

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ID:	50954
    Looking at getting a replacement.
    Not sure on the current rating.
    Maths not my thing 😃
    Any assistance from you wizards will be grateful
    How did you verify the Pwr Xfmr is bad? With F1 and F2 fuses removed, does the transformer immediately pull current, either on a light bulb limiter or bringing it up on a variac? Or, is the primary now open circuit?

    Following Randall's suggestion, for a brief moment in time, you had double the voltages, though trying to charge those 35V-rated filter caps no doubt objected to get to the 2X supply voltages, you had all of the electronics subjected to that -near-2X voltages state.

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    Logic is an organized way of going wrong with confidence

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    Long story short. Owner has been given it from after a death of family member. Plugged it in to 230v. Transformer is 117v. When I plug into a 110v step down it blows the fuse on step down tx.. I believe the board is ok. Transformer is NLA so I need a replacement or I can get this 117v rewound.

    He wants to get it working. So I need a new 230v tx

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    Old Timer J M Fahey's Avatar
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    (kneeling inside the closet: ... "is the room safe to enter now?")

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    Juan Manuel Fahey

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    Old Timer J M Fahey's Avatar
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    "Ok, Iīll chance it"

    1)
    I believe the board is ok.
    So far, thatīs Faith/Hope based only
    Might work, might not.
    In any case, it can be repaired.
    Do you think you are up to it?
    Meaning: reading the schematic, identifying parts , replacing bthem.
    Principal suspects: power transistors and their drivers.

    2) in any case test the transformer *alone* , you might be surprised: remove secondary side fuses F1 and F2 and plug transformer again into 110V mains with just F3 ... what happens?

    3) you need a 17+17 or 18+18VAC transformer, 1A or more, so one rated 60 to 90VA , 220V primary of course, will be fine.

    18+18 VAC in that power range are very popular for LM3886 chipamps, so should be relatively easy to find.

    Sadly you give no clue about where you live, so we canīt suggest a supplier.

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    Juan Manuel Fahey

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    Supporting Member Jazz P Bass's Avatar
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    Here is a pic that I came across of the tranny in question.

    Click image for larger version. 

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    Thank you. Now I've got an idea on what to get.
    A

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