5725A
Instruction Manual
Switching Section |
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MOSFETs Q301/Q317 and Q302/Q318 (each in parallel) are
The MOSFET switches are controlled by the signal at TP305. When this point is at +5V, the series connected
Transistors Q303/Q321, Q311/Q323, Q315/Q322, and Q316/Q324 are emitter followers that prevent Q305 and Q307 from experiencing excessive
Resistors R310/R311/R306 provide a divided voltage for
Control over the potential at TP305 is controlled in one of the two following ways:
1.In normal operation (P301 plugged onto the E301 header where the label SYS appears, pins 1 and 2), the microprocessor strobes the control data HVSUPPLY* into U302 by pulsing HVSTROBE. This action occurs in parallel with writing HVSUPPLY* information into a latch on the High Voltage Sense assembly (A6), but there the sense of the HVSTROBE line is inverted.
Transistor Q304 provides correct polarity to the clock of U302. At any time, the supply can be switched off (i.e., TP305 brought to +5V) independent of the processor by the
2.To turn on a Power Supply assembly (A4) by itself for troubleshooting, you can plug P301 onto the E302 header where the label MAN appears (pins 2 and 3). This allows