REPLACING THE POWER SWITCH ON A COMMODORE MONITOR 2-28-06.
REPLACING THE POWER SWITCH ON A COMMODORE MONITOR Latest updates and corrections: 2-28-06 The standard CBM 1084 series and 1902A monitors made by Philips have a separate power supply board mounted on a slide-in plastic tray. The power switch is fastened with two screws to the front end of that tray so it sits just behind the front panel push button assembly. Four wires connect the switch to the chassis. Note the position of the color coded wires and install them the same way on the new switch. View how it looks before and after switch replacement at http://staff.washington.edu/rrcc/uwweb/pics/1084.jpg Position the monitor face down on a cloth or newspaper to prevent scratches on the front panel. Five screws must be removed to pull the rear cover off the monitor. Disconnect the speaker plug from the center upright sub-board as you remove the rear cover. To remove the PS tray from the cabinet, unplug two connectors on the PS board and unsolder the two braided ground straps from the bottom metal shield. One other braided strap connects the PS board to the CRT board, and that one may need to be removed to be able to pull the tray all the way rearward and out. The release for the tray is inside the square cutout underneath. Push the release in slightly with a small screwdriver as you pull the tray rearward. The mounting holes of the replacement switch may be misaligned with the holes in the plastic tray by a fraction of an inch. If so, the holes in the tray may be trimmed (elongated) slightly with a thin sharp knife so the switch will fit. Although the new switch is designed for machine screws, the original self-tap screws will work fine. Once the wires are soldered, the tray may be pushed back into its slot. You may have to dress the wiring out of the way if it snags or binds. Resolder the three shield braids to their previous places and reconnect the two plugs to the PS board. Try the switch a few times to make sure it latches and unlatches properly before putting the rear cover back on. As you reattach the cover, don't forget to reconnect the speaker plug. The CBM 1902 and 2002 monitors were made by Fujitsu and have a different layout for the power switch than a 1084. It mounts directly to the front panel and uses only two wires. Place the monitor face down on a cloth. Six screws must be removed to pull the rear cover off the monitor. Raise the cover slightly and disconnect the speaker plug by squeezing/pulling the connector, then remove the cover. Note how the original power switch is mounted and how the wires are connected with a small PC board. That board can be discarded along with the switch and the two wires soldered directly to two terminals of the new switch. The other two terminals of the switch are unused. The original installation didn't use the switch mounting holes but just two large washers as clamps at the edges of the switch. The new switch can be mounted in a similar fashion. However, a slightly longer switch actuator may not allow it to release properly when turned off. If so, you can use extra washers underneath the edges as spacers or you can trim a small amount off the end of the switch shaft, no more than 1/8". Observe view before & after the switch replacement: http://staff.washington.edu/rrcc/uwweb/pics/1902.jpg. The CBM (Amiga) 1080 uses a completely different chassis made by Toshiba. The power switch mounts on the front panel, similar to the 1902 and 2002 versions. The small PC board must be left in place as it also connects to the front panel power indicator LEDs. However, the two switch wires may be cut off and soldered directly to two terminals of the new switch. As before, you can use a few washers as shims if the switch actuator is too long and it doesn't release all the way when turned off. An alternative would be to trim no more than 1/8" off the end of the switch shaft. Note that only two switch terminals are used. View the 1902.jpg image