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HR-1680

[Block Diagram]  [Rear Panel]

Replace the regulator on the D board with a modern design.
[Power Supply] [ [D Board]

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[A Brasspounder Improves Heath's HR-1680]
73 Magazine, January 1980, pages 76-78, 80, 82

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[Large Full Page Schematic older version]
[Large Full Page Schematic newer version]

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Bulletin No: HR-1680-10, July 8, 1977
Front End Oscillates (One wire preselector mod)

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A - Front End (85-1846-x / 85-2072-1)

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Two wires to preselector version.

PC Board (85-1846-x)

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X-Ray (85-1846-x)

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Schematic (85-1846-x)

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One wire to preselector version.

PC Board (85-2072-1)

Yes, R103, R104, and R105 are burned and should be replaced.

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X-Ray (85-2072-1)

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Schematic (85-2072-1)

UHD Schematic

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B - VFO (85-1731-2)

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PC Board

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X-Ray

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Schematic

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C - HFO and Calibrator (85-1732-x / 85-1954-1)

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PC Board (85-1736-x)

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X-Ray (85-1736-x)

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Schematic (85-1736-x)

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PC Board (85-1954-1)

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X-Ray (85-1954-1)

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Schematic (85-1954-1)

UHD Schematic

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D - Audio and Regulators (85-1734-6 / 85-2654-1)

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PC Board (85-1734-6)

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X-Ray (85-1734-6))

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Schematic (85-1734-6)

UHD Schematic

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PC Board (85-2654-1)

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X-Ray (85-2654-1)

The PC artwork to replace the regulator with a LM317 is not available. The LM317 input is right pin (3). the output is the center pin (2).

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Schematic (85-2654-1)

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Power Supply

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