Resistance And Voltage Measurem.ents - Raytheon DIDS-400 Series Technical Manual

DIDS-402-2AMI3
a. Locate and re:move the combination on/off brightness control knob.
b. Remove the four screws (black) holding the metal mask to the front
plate assembly.
c. Remove all 31 screws (silver) securing the cover to the front plate.
d. Remove all 8 screws (silver) at the rear of the unit. These screws
are located near the BNC connectors protruding from the rear cover.
e. Obtain as sistance and gently slide the cover to the rear while pulling
the display chassis forward.
Once the cover is removed, the internal assemblies are exposed for
exa:mination. Check the following points for good mechanical and electrical
connections:
a. All terminal screws on both power supply assemblies (see figures
1-5 and 1-6).
b.
All wiring connections to the printed circuit board assemblies (see
figures 1-3 through 1-7).
c. The monoscope and CRT tube sockets to assure that they are firmly
connected (see figures 1-4 and 1-7).
d. The HV anode lead on the CRT (see figure 1-5).
2-3.2 Resistance and Voltage Measurements
Before applying power to the Display Terminal, measure the electrical
resistance between each power supply output line and ground. Themeasured
resistance varies, depending upon equipment control settings and component
tolerances. In no case should the resistance to ground (chassis) measure 0 ohms;
this indicates a shorted condition. No shorts should be discovered, since the
Display Terminal undergoes extensive testing at the factory. However, careless
handling during shipment can result in shorts which must be corrected prior to
applying power to the equipment.
The dc output wiring is color coded throughout the equipment as follows:
Output Color Code
+5 vdc gray
-22 vdc
purple
+22 vdc red
+100 vdc orange
+540 vdc yellow
-1. 2 kvdc red (high voltage insulation)
2-3