Tools:

• Philips Screwdriver with magnetic medium head
• Cordless screwdriver (or drill with clutch) with Philips bit with magnetic head (optional)
• Standard head screwdriver or chip puller

Replacement Instructions:

1. Power off monitor and logic unit.
2. Remove the monitor and disconnect all cables from the 54xx logic unit.
3. Turn the logic unit up-side-down.
4. Remove the four screws at the bottom of the logic unit located at each corner.
5. Turn the unit right-side-up.
   ***BE CAREFUL PERFORMING THE NEXT STEP***
6. a) On units with power switch in back, carefully open the cover taking notice of the LED wire lead.
   b) On units with power switch in front, carefully open the cover. You may need to push the top cover over the top of the power switch.
7. On units with the power switch in back, either remove the modular wire connector which goes to the LED power indicator from the logic board or lay the cover to the side.
8. Ground yourself by touching the twinax cable for a few seconds.
9. Replace the EPROM located at position U3 (for base with power switch in back) or U8 (for base with power switch on the front & version CH, M5250-C), U13 (for base w/power sw on front & version NH, M5250-A). This chip will have a white sticker with printed letters and numbers on it. BE SURE TO PLACE THE EPROM WITH THE CORRECT ORIENTATION INTO THE SOCKET. The notch should point the same direction as the other chips above and below this one.
10. Connect the modular wire connector which goes to the LED power indicator to the logic board if it was disconnected.
11. Place the top cover on the logic unit.
12. Turn the unit up-side-down, replace the screws removed in step 4.
13. Turn the unit right-side-up.
14. Replace all cables removed in step 1 except for the twinax cable Y-connector.
15. Connect keyboard to logic unit.
16. Power on the logic unit while holding down the RESET + TAB + DEL + CMD12. (RAM reset)
17. You should see SELECTIONS HAVE BEEN RESET TO THE DEFAULT VALUES message.(if not, the chip is not in properly, or the RAM did not reset to default, repeat this step).
18. Press the spacebar to enter OFF-line setup, reset all address, emulation, printer information.
19. Plug in the twinax cable Y-connector, and exit setup to get the sign on screen.