Hammond Organ Technical Information
Replace Manual Chassis

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S-78. MANUAL CHASSIS.

5-79. Replacement of manual chassis will be accomplished as follows:
  1. Remove the rear panel of the console. (Reference paragraph 1- 10.)
  2. Remove the four screws on the left- and right-hand side panels of the music rack.
  3. Lift the side panels to tilt the bottom of the rack, and then remove the rack by pulling outward.
  4. Remove the 4 chassis bolts (under the con-sole) and the 2 machine screws (under the front lower rail) that secure the entire manual chassis in place.
  5. Disconnect all preamplifier leads.
  6. Loosen set screw in expression control lever arm and detach arm from preamplifier.
  7. Remove preamplifier from shelf after taking out mounting screws.
  8. Unsolder (do not cut) the 79 manual leads, 2 ground leads, 3 pedal signal leads (red, orange, and yellow), and the pedal filter leads (brown and black).
  9. At the power terminal panel, unsolder the live wires leading to the manual chassis start and run-motor switches. Determine these leads by tracing the leads from the switches.
  10. Detach pilot lamp bracket by removing two wood screws.
  11. Unsolder eight scanner wires from terminals on back of drawbar base.
  12. Unsolder brown wire from vibrato line.
  13. Tie the disconnected cables to the chassis to prevent damage to the other console components when the manual chassis is removed.
  14. Remove the manual chassis through the rear of the console. Slide the chassis out carefully. Because of frame construction, the chassis will drop suddenly before it is entirely out of the console. Two men are required to remove the manual chassis from the console.
  15. Install a replacement chassis by reversing the procedure above. (See Figure 2-2 for cable connections).


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