252Shuttle Electrical Shorts TestThis procedure checks for metallic debris and checks for hammer coils shorting to the shuttle frame.The hammer driver circuit board attached to the shuttle frame assembly can attract metal objects because of the magnets inthe hammer bank. Such stray metal pieces can cause electrical shorting and damage to the shuttle assembly. (The hammerdriver board does not have a protective cover because of concerns about component temperatures.)IMPORTANT Do this check —a) If you removed the shuttle cover during servicing and before you re-install the shuttle cover.b) Before you replace the controller board.1. Prepare the printer for maintenance (page 313).2. Remove the shuttle cover (page 326).3. Check the shuttle driver circuit board area for any foreign metal parts or objects (paper clips, staples, screws, chips ofmetal, broken shuttle spring fragments, etc.).4. If you find any foreign metal parts or objects, carefully remove them.5. Disconnect the hammer bank logic cable (P04) and the hammer bank power cable (P05) at the shuttle.6. Set your Ohmmeter to the 10K Ohm scale or the scale closest to 10K Ohms.7. Hold the two meter leads apart from each other (not touching anything) and note how your meter indicates an open circuit.For example, some meters read OL (Over Load), -1, flashing display, infinite resistance, etc.8. Attach the common meter lead (usually black) to the shuttle frame.9. Touch the positive meter lead (usually red) to another part of the shuttle frame and verify continuity. (Continuity is a lowresistance reading of less than 1 Ohms.)10. Attach the common meter lead to the shuttle frame, touch the positive lead to pins 2, 4, 6, 8, and 10 of hammer bank powerplug J05 located on the terminator board on the shuttle. (Pin 1 is the right-most pin as you face the printer.) Hold thepositive lead for a few seconds on each pin allowing the meter to stabilize, then read the resistance:1) If the resistance of any pin is less than 1000 Ohms, replace the shuttle frame assembly (page 362).2) If pin resistances are 1000 Ohms or greater (including an “open” reading as in step 7), the shuttle passes the test and isprobably okay. Reconnect hammer bank logic cable (P04) and hammer bank power cable (P05) to the shuttle.11. Install the shuttle cover assembly (page 326).12. Return the printer to normal operation (page 314).
