Cardiac Defibrillator Interface Board Repairing starts from the site observation, it was found that the power regulator key indicator light was always on, because the voltage-stabilizing indicator light is always on, it is judged that the voltage button is stuck short-circuited, and the fault is still found after welding the button with a soldering iron.
However, according to the fault phenomenon, it is still judged that the fault is on this interface control board. At this time, interface board has been removed and observed it carefully. No obvious short-circuit traces were found.
After cleaning the entire board with alcohol, the fault remained. Since this board is a four-layer PCB board and it is a patch component which makes it difficult to observe, so flashlight has been used with a magnifying glass, a multimeter and other tools to analyze and observe carefully, restore the circuit diagram in reverse engineering. According to the printed circuit board schematic diagram, it can be seen that the extension of the cutter head is effectively controlled at a low level (this signal passes T TL to MOS, and then enters the logic control CI through an NOT gate).
At first, it was suspected that the capacitor short between the control electrode, ground caused voltage clamping at low level, but after the removal of capacitance, and the capacitance was still found to be normal. Use a multimeter to measure the channels one by one and find that the voltage disappears when the SV power supply enters a resistor in front of the push button switch. It is judged that the resistor is disconnected from the printed copper wire, but it is difficult to observe with the naked eye.
Finally, use a thin copper wire directly to connect this resistor to the power supply copper pad to return to normal, and the Cardiac Defibrillator Interface Board has been successfully repaired.
