TM 11-6625-3145-14
Theory of Operation-318/338 Service
Figure 4-11. 318/338 Simplified diagram of the serial acquisition and RS-232C circuit.
Battery Switch. The battery switch circuit consists of A07Q140, A07Q141, A07C160, and A07CR170. When the system
power comes up, A07Q140 and A07Q141 turn ON. Pin 18, connected through a 2K resistor, and pin 24 of A07U7 are
connected to the Vcc line. When the system power goes down, A07Q140 and A07Q141 turn OFF. Pin 24 and pin 18 of
A07U7 are connected to the battery power. A07CR170 protects the battery from charging. A07C160 adjusts the switching
speed between two power sources.
Battery Voltage Checker. The battery voltage checker circuit consists of A07Q170 and A07U32D. A07Q170 compares
the battery voltage supplied to its base with the voltage at its emitter (2.90V). If the battery voltage is low (<2.2V), the input
at pin 9 of U32 is high. If the battery voltage is normal (>2.2V), A07U32 pin 9 is low. Pin 8 of A07U32 is tied to the CPU
via data bus line 7.
Random Access Memory. A07U1 is a 2040-byte random access memory. It uses a battery backup power source to
retain data when system power is off.
4-31
Summary of Contents for 318
Page 119: ...318 VERIFICATION AND ADJUSTMENT PROCEDURES ...
Page 182: ...338 VERIFICATION AND ADJUSTMENT PROCEDURES ...
Page 253: ...318 ___________________ TROUBLESHOOTING TREES ...
Page 344: ...338 TROUBLESHOOTING TREES ...
Page 517: ...TM 11 6625 3145 14 318 338 4434 923 318 Block Diagram ...
Page 518: ...TM 11 6625 3145 14 318 338 4434 924 338 Block Diagram ...
Page 519: ...TM 11 6625 3145 14 318 338 4434 925 318 Acquisition Module Wiring Diagram ...
Page 520: ...TM 11 6625 3145 14 318 338 4434 926 318 338 Mainframe Wiring Diagram ...
Page 521: ...TM 11 6625 3145 14 318 338 4434 926 338 Acquisition Module Wiring Diagram ...
Page 522: ...TM 11 6625 3145 14 318 338 4434 928 Figure 9 1 318 A01 Input A Board Component Locations ...
Page 526: ...TM 11 6625 3145 14 ...
Page 528: ...TM 11 6625 3145 14 Figure 9 3 318 338 A03 ACQ Control Board Component Locations ...
Page 532: ...TM 11 6625 3145 14 ...
Page 536: ...TM 11 6625 3145 14 ...
Page 538: ...TM 11 6625 3145 14 ...
Page 539: ...TM 11 6625 3145 14 ...
Page 540: ...TM 11 6625 3145 14 ...
Page 541: ...TM 11 6625 3145 14 ...
Page 542: ...TM 11 6625 3145 14 Figure 9 8 318 338 A10 CRT Board Component Locations ...
Page 544: ...TM 11 6625 3145 14 Figure 9 9 318 338 A11 Inverter Board component Locations ...
Page 546: ...TM 11 6625 3145 14 Figure 9 10 318 338 A12 Regulator Board Component Locations ...
Page 551: ...TM 11 6625 3145 14 Figure 9 12 338 A01 Input A Board Component Locations ...
Page 553: ...TM 11 6625 3145 14 318 338 SERVICE ...
Page 554: ......
Page 555: ...PIN 058584 ...