182Chapter 4 Shuttle Electrical Short CheckShuttle Electrical Short CheckThis procedure checks for metallic debris and checks for hammer coilsshorting to the shuttle frame.The hammer driver circuit board attached to the shuttle frame assembly canattract metal objects because of the magnets in the hammer bank. Such straymetal pieces can cause electrical shorting and damage to the shuttleassembly. (The hammer driver board does not have a protective coverbecause of concerns about component temperatures.)IMPORTANT Do this procedurea) If you removed the shuttle cover during servicing and before youre-install the shuttle cover.b) Before you replace the controller board with a new or refurbishedboard.1. Prepare the printer for maintenance (page 154).2. Remove the ribbon cartridge. (Refer to the User’s Manual.)3. Remove the shuttle cover assembly (page 203).4. Check the shuttle driver circuit board area for any foreign metal parts orobjects (paper clips, staples, screws, chips of metal, broken shuttle springfragments, etc.).5. If you find any foreign metal parts or objects, carefully remove them.6. Disconnect the hammer bank logic cable (P04) and the hammer bankpower cable (P05) at the shuttle.7. Set your Ohmmeter to the 10K Ohm scale or the scale closest to 10KOhms.8. Hold the two meter leads apart from each other (not touching anything)and note how your meter indicates an open circuit. For example, somemeters read OL (Over Load), -1, flashing display, infinite resistance, etc.9. Attach the common meter lead (usually black) to the shuttle frame.10. Touch the positive meter lead (usually red) to another part of the shuttleframe and verify continuity. (Continuity is a low resistance reading of lessthan 1 Ohms.)11. Attach the common meter lead to the shuttle frame, touch the positivelead to pins 1 through 10 of both hammer bank power plugs J05 and J06located on the terminator board on the shuttle assembly. Pin 1 of eachplug is the right-most pin as you face the printer. Hold the positive lead fora few seconds on each pin allowing the meter to stabilize, then read theresistance:a. If the resistance of any pin is less than 1000 Ohms, replace theshuttle frame assembly (page 239).b. If pin resistances are 1000 Ohms or greater (including an “open”reading as in step 7), the shuttle passes the test and is probably okay.Reconnect hammer bank logic cable (P04) and hammer bank powercable (P05) to the shuttle12. Install the shuttle cover assembly (page 203).
