DETAILED BLOCK DIAGRAM
5.3 CORRECTIVE MAINTENANCE
5.3.2 Removal and Replacement
Opening ADM 36 Cover (see figure 5-1) 1. Remove the two phillips-head screws
located on the bottom of the terminal base.
2. Disconnect the external interface connection(s) at the rear of the ADM 36.
3. Lift the cover upwards and rearwards from the front until it is lowered to rest on the table.
4. To remove the cover, disconnect the cable connecting the main PCBA to the monitor. Slide the cover toward the left until it is free of the hinge pins, then lift the cover from the base.
Note that the cover should not be removed for adjustments required on the ADM 36.
Removing the Main PCBA
1. Remove the external interface connection(s) at the rear of the ADM 36.
2. Open the terminal cover.
3. Remove all cable connectors from the upper surface of the circuit board.
4. Remove screw from center of main PCBA and unlatch plastic locks at front end of logic board by pressing towards front of terminal.
5. Lift the board upwards and pull it forward until the RS-232 connectors clear the back housing, then lift the board out of the base.
To replace the main PCBA, perform the above procedures in the reverse order.
Removing and Replacing Key Switch Assembly (Futaba Keyboard)
For this section, refer to figure 5-2.
The tools required to remove the key switch assembly from the keyboard are:
• Soldering iron (low temperature)
• Solder sucker or wicking device
• Small flatblade screwdriver
DP336 5-5
To remove the key switch, follow the directions below:
1. Remove the keyboard from the housing.
2. Remove the solder from the three contacts (dewick) with a low heat soldering iron so as not to damage the circuit pads. The contacts will protrude about 1132 inches beyond the back of the keyboards. Make sure that the contacts are completely free of any solder by brushing them with your finger. The contacts should move freely.
3. Tum the keyboard over so that the keyboard is up.
4. Use the small flat screwdriver to disengage the four plastic retaining clips inside the key assembly.
5. Remove key assembly.
Instructions for key switch installation are as follows:
1. Insert a new key assembly.
2. Turn the keyboard over so that the solder side is up.
3. Solder the three contacts into place with a low heat soldering iron.
4. Tum the keyboard over so that the keyboard is up and install the keycap.
5. Install the keyboard into the keyboard housing.
Removal and Replacement of the Monitor
The CRT with its steel mounting frame, the flyback assembly, and the circuit board comprise what is known as the ADM 36 monitor.
WARNING
I
Discharge anode voltage to ground before attempting to remove the CRT, the flyback assembly, or the circuit board.
Figure 5·2. Futaba Key Assembly
To remove the CRT, proceed as follows:
1. Disconnect the black ground wire on the left side of the CRT.
2. Remove the connector from the base of the CRT.
3. Remove the anode connector from the right surface of the CRT.
4. Using a socket wrench, remove the four screws on the sides of the CRT. Support the CRT with your hand while removing the last two screws.
To install a new CRT, performthe above steps in reverse order.
Follow the steps below in order to remove the flyback assembly.
1. Disconnect the anode connector from the CRT.
2. Disconnect the Molex connector that connects the flyback assembly to the monitor circuit board.
3. Use a lI4-inch socket to loosen the hex-head screw that clamps the flyback assembly to the MCB mounting plate.
4. Lift the flyback assembly upwards until the screw clears the slot in the mounting plate. Remove the assembly from the cover.
When installing a new flyback assembly, be sure the diode is installed with the white ring end towards the CRT.
To install a new flyback assembly, perform the above steps in reverse order.
Removal and Replacement of the Monitor Control Board Assembly (PCBA)
Removal of the monitor control/board is as follows:
1. Disconnect the ADM 36 from the power source and remove the external interface connection(s) at the rear of the ADM 36.
2. Open the ADM 36 cover by loosening the two phillips-head screws at the front comers of the terminal base and lifting the cover upwards and rearwards. Rest the comer on the table or desk.
3. Remove the power supply cable and monitor cable connections in the upper surface of the main PCBA.
4. Remove the two screws holding the flyback transformer bracket.
5. Remove yoke connectors. Remove the connector from the base of the CRT.
6. Disconnect the black ground wire from the CRT DAG clip.
7. Remove the entire main PCBA, flyback assembly, and metal plate as a unit.
To install a new monitor control board, perform the above steps in reverse order.
WARNING
I
A residual charge may exist across the flyback diode and a shock hazard exists even though insulated. Also, ensure that the diode is making proper contact in the connector.
Removal and Replacement of the Switching Power Supply
The following three steps explain the power supply removal:
1. Remove the main PCBA.
2. Remove the two hex nuts securing the power supply and hold down the plate.
DP336 5-7.
3. Tum the hold down plate around until the power supply is exposed.
4. Remove the hex nut securing the power supply.
5. Remove the cable connector from the upper surface of the power supply board.
6. Pull the power supply downwards to remove it from the ADM 36 base.
To replace the power supply PCBA, perform the above steps in reverse order.
WARNING
I
Adjustments must be made with power applied to the ADM 36. To avoid, electrical shock, use a non-conducting screwdriver for all applicablf adjustments.
5.4.1 B rig h t n e s sAd jus t men t Procedure for the AD M 36 To adjust the ADM 36 monitor brightness for proper operating level, the following procedure is to be followed:
2. Select setup mode which displays tab fields.
3. Use down arrow key on keyboard to set contrast to lowest limit. Display should be blank.
4. Adjust brightness control CW on monitor board until raster appears. Then turn brightness control CCW until raster disappears and the reverse video tab fields just disappear.
5. Use up arrow key on keyboard to'adjust contrast for best display.
6. Verify proper video display as follows:
Make sure unit is in local mode.
Depress set-up key to remove unit from set-up mode.
Depress ESC [1m.
Enter 3 "E" characters.
Depress ESC [Om.
Enter 3 "E" characters.
Depress ESC [2m.
Enter 3 "E" characters.
Verify three levels of intensity are displayed - bold, normal, reduced - and
are clearly visible.·
Note
Some adjustments of the contrast may be required in set-up mode. A Shift S should then be performed to save current contrast level in NVR.