Before overhauling the timing logic circuit should be as familiar as possible with the structural principles of the system and the circuit, and then is to analyze the fault characterization characteristics, as far as possible to narrow the scope of the fault generated. Higher-grade medical equipment generally comes with a self-diagnostic program, which can be fully utilized to find faults and locate them to a smaller extent. Interface cards, printed boards and sockets may be loose or off-center sockets lead to poor contact and lead to failure, in fact, many failures are indeed generated, which can be used to clean the interface with anhydrous alcohol wipe and then re-inserted after fixed. In addition, digital systems are often connected to other systems through external communication lines (RS232, MODEM, IEEE-488, etc.), and the connection line is usually very long, but also may be exposed to sources of electronic interference, such as relays, motors, transformers, large X-ray machines, rainy days, lightning, etc., the connection port poor contact and electronic interference sources of electromagnetic interference (EMI) may produce erroneous data transmission, or even damage to the relevant components. It is best to find out the source of electromagnetic interference and eliminate it, followed by improving the working environment (e.g. humidity and temperature, etc.), strengthening the shielding, or switching to a good shielding performance of the connecting cable.
The overhaul of timing logic circuits have many methods of skills, must be summarized through the long-term practical work to better diagnose, find, troubleshooting, and improve the maintenance of timing logic circuits technical level.