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For the technically-curious, study the power supply sections of the RCA 630TS / 1948 RCA 8TS30 schematic (Sams 54-18) and the Fada TV30 / 1948-1/2 RCA 8TS30 schematic (Sams 74-3) and note the absence of the speaker and ion trap field coils from the Sams 74-3 schematic and the presence of speaker and ion trap field coils in the Sams 54-18 schematic. Also note how the focus controls operate by increasing resistance as the control is rotated in the CW direction ... increasing focus coil current by shunting less current away from the focus coil. On the 54-18 schematic, the speaker field coil will be between the +300V and +280V points, the focus coil and ion trap are between the -18V and -100V points. On the 74-3 schematic, the speaker field will be replaced by a filter choke and some resistors, the focus coil and control network will be between the -18V and -100V points with some resistors substituted for the ion trap coil.
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