ZOLL M Series Defibrillator Rev R - Manual (Page 134)

M Series Service Manual
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Discharging Initiating a discharge provides voltage to the solid state patient relay and notification to the Main System Board through
the PADMON signal. The Main System Board then controls activation of the solid state patient relay (for DSW only).
Energy delivered to the patient goes through a wave shaping inductor to create a defibrillation waveform compliant
with AAMI Standards. When the patient discharge SCRs are deactivated, the safety relay closes to internally dissipate
any remaining energy.
If the M Series is in the self test mode, the energy is delivered internally. The microprocessor calculates the actual
delivered energy from the current waveform and displays a TEST OK message on the display, if the self test meets the
appropriate criteria. If the criteria are not met, a TEST FAILED message displays.
High Voltage Capacitor Monitor
Before charging the defibrillator, the High Voltage Capacitor monitor runs a self test to check the pace relay. The pace
relay controls the high voltage circuitry configuration either for generating pace pulses or for charging the high voltage
defibrillation capacitor.
The defibrillator capacitor is shunted for safety reasons with a resistor and relay to internally dissipate any energy
remaining. When the Main System Board initiates a charge, this relay opens by providing a low level on signal
XSAFREL. The safety relay is a biased reed switch. The relay is driven by Q318.
The pace relay driver is a grounded source switch Q308 that is biased on by R593. It is held off by Q330 when
XPACEREL is '1' false. When XPACEREL comes true, Q330 is turned off, and Q308 is no longer clamped off.
The high voltage capacitor is charged by converting the system battery voltage to a pulsed high voltage by way of
transformer T1. The basic operating frequency signal that is used to switch transistor Q1 providing current in the
primary windings of the transformer T1 originates in the system board’s gate array.
When the high voltage capacitor is charging, the Main System Board independently monitors the capacitor voltage
through signal VMON. If the Main System Board detects an improper level, it halts operation by setting SAFE high.
This disables the SCR discharge circuitry and flyback transformer drive.
The solid state patient relay discharges via the signal PATREL_DRV generated by XPATREL and Q304, Q323, and
Q322. PATREL_DRV is disabled when XPACE_SEL is at a logic low.
When the solid state patient relay activation completes, the Main System Board releases the XPATREL signal. Several
hundred milliseconds later, the safety relay closes to ensure the high voltage capacitor energy is completely dissipated.