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#16034
Ted FletcherTed Fletcher
Keymaster

    The power rails on the SC2.2 are derived from a single 15V regulator which is ‘crowbarred’ up to 30V by standing the control 15V above the negative rail.

    The centre voltage is decided by IC7 which produces a ‘half-rail’ point. So there is no way of setting the negative rail separately. If the voltages are wrong, it’s most likely that IC7 has failed in some way.

    I suggest that you replace IC7, and make sure that the 2N5401 is good…. the regulation looks to be slightly off :(

    It’s very unusual to see this sort of fault; it suggests that the unit has been hit with 240VAC with the fuse selector in the 120V position!

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