Point Nix 3D Combi malfunction definition.

If the Point Nix 3D Combi tomograph hangs and crashes, or starts from the second time - the reason may be on the Signal Processor board.

In the Signal Processor, near the microcontroller, there is an SMD chip MB3773.

MB3773 is a voltage supervisor and watchdog timer.

MB3773 is Job is as follows.

1. Keeps the controller in a reset state until the supply voltage reaches the set point and stabilizes (POR).

2. 2. Makes the controller reset when the supply voltage drops below a critical level or when there is a sudden voltage drop (BOR).

MB3773 is a threshold comparator. The comparative threshold is set by the value of the internal voltage reference source. Usually 1.24V.

For smoothing the voltage reference, is used an external capacitor in the MB3773, the loss of capacitance of which leads to a voltage spikes. This is a SMD capacitor CP3, with a nominal value of 0.47 microfarads, which stands on the Pin1 of the chip.

Pulsations of voltage reference cause a microcontroller reset signal. As a result, the Point Nix 3D Combi scanner is malfunctioning.

The repair of a Point Nix 3D Combi tomograph consists in re-soldering or replacing the CP3 capacitor, with a nominal value of 0.47 McF, on the Sinal processor board.

In the photo of a fragment of the Point Nix 3D Combi's Signal Processor board, the CP3 capacitor is circled in white.

MB3773 - DC modes.

1 - 1,3
2 - 0,03
3 - 2,45
4 - 0
5 - 4,9
6 - 1,24
7 - 1,4
8 - 4,9

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