Nov. 1997 © TOSHIBA
18 - 53
4560/4570 RADF
18.11.2
+5V power circuit
This is a circuit which generates DC +5V voltage supplied to CPUs, logic ICs, etc. DC +24V supplied
from CN5 is dropped to +5V by a 3-terminal regulator IC9. In this circuit, R65 and R64 are protective
resistors which compensate for the power loss occurring due to the generation of +5V. When current
consumption for the +5V line is approx. 80 mA or less, the power loss is compensated for by R65 and IC9
but when the consumption current value exceeds 80 mA, the input voltage at IC9-pin 1 decreases due to
voltage drop in R65. When the emitter voltage of Q13 becomes 0.6V lower than its base voltage, Q13
starts conducting and by making excess current flow through R64, shares a part of the power loss.
In this way, by varying the protective resistance value with the magnitude of consumption current, the
heat caused by the power loss is distributed and dissipated.
Summary of Contents for 4560
Page 210: ...Nov 1997 TOSHIBA 13 43 4560 4570 ADU 13 8 7 Harness connection diagram ...
Page 213: ...4560 4570 ADU 13 46 Nov 1997 TOSHIBA 13 8 9 PC board assembly ...
Page 238: ...Nov 1997 TOSHIBA 14 25 4560 4570 CIRCUIT DIAGRAMS 14 5 Power Supply Circuit PS ACC A 115V ...
Page 239: ...4560 4570 CIRCUIT DIAGRAMS 14 26 Nov 1997 TOSHIBA B 230V ...
Page 243: ...Nov 1997 TOSHIBA 16 1 4560 4570 PC BOARD 16 PC BOARD ASSEMBLY 16 1 PWA LGC ...
Page 244: ...4560 4570 PC BOARD 16 2 Nov 1997 TOSHIBA 16 2 PWA PNL ...
Page 245: ...Nov 1997 TOSHIBA 16 3 4560 4570 PC BOARD 16 3 PWA KEY1 16 4 PWA KEY2 ...
Page 246: ...4560 4570 PC BOARD 16 4 Nov 1997 TOSHIBA 16 5 PWA ERS ...
Page 247: ...Nov 1997 TOSHIBA 16 5 4560 4570 PC BOARD 16 6 PS ACC A 115V ...
Page 248: ...4560 4570 PC BOARD 16 6 Nov 1997 TOSHIBA B 230V ...
Page 249: ...Nov 1997 TOSHIBA 16 7 4560 4570 PC BOARD 16 7 PS HVT ...
Page 342: ...4560 4570 RADF 18 84 Nov 1997 TOSHIBA 18 16 2 Control PC board circuit PWA F LGC 770 ...
Page 343: ...Nov 1997 TOSHIBA 18 85 4560 4570 RADF 18 16 3 Harness connection ...