Analysis of causes and maintenance cases of monitor white screen failure
Monitor is one of the most commonly used medical devices in hospitals. it can monitor the vital signs of single or multiple patients, such as ECG, blood oxygen, blood pressure, body temperature and heart rate, and it is an important tool for doctors to carry out clinical treatment. In the actual use process, some failures of the monitor often lead to its failure to work normally, and even lead to medical disputes. Here are two examples of patient monitor failure maintenance in our hospital EEG machine.

1. pregkang
Pc - 9000 boot display white screen
Solution: because the machine does not have VGA, SV, av and other external display outputs, it is temporarily impossible to confirm whether its character display is normal or not, so it is measured by blood pressure after starting up, the air pump is normally started, and the cuff is connected to start the blood pressure measurement, with periodic attenuation.
Connecting the blood oxygen probe can hear the normal pulse sound, so it is preliminarily judged that the machine is a simple display failure. After disassembling the machine, it was found that the main board of this machine is PCM - 3336 made in Taiwan, and the main board is equipped with c & t 65545 display chip to drive the liquid crystal display, which has VGA output function. however, as the machine takes a long time to produce and does not have VGA output port at the factory, it is unable to use the external screen. at the same time, the main board has stopped production, and the same model can't be found, so it is replaced by the same PCM - 3496 lanyu technology industrial main board.
As PC - 9000 is based on dos platform, we should install dos on the dos disk according to the new motherboard's own instructions, and then access the PC - 9000 card according to the definition of PC 104, conduct computer test and check it as normal. As the mainboard and display screen are too old, the new generation mainboard and display screen will be replaced together.
2. Coleman
Fetal sound monitoring star - 5000c
The logo of " Coleman" displayed on the startup screen is normal, and the phenomenon of white screen failure is displayed after entering the system: logo can only be displayed normally when starting the system, and it cannot enter the system normally.
Solution: according to the fault phenomenon, it is preliminarily judged that the screen itself is normal, because the logo of the manufacturer can be displayed normally when starting up, and after starting up, the probe can be used to make a sound, and the system should be normal, but the display screen is faulty.
However, the manufacturer did not provide any valuable maintenance information, so the machine can only be disassembled first to understand the system structure. after disassembling the machine, it was found that the LCD output port of the main board was led out to the key board through 40 pin ribbon cable, and the fetal sound monitoring basic function was normal, so it was judged that the whole machine was basically normal except for display.
Therefore, the 40 pin ribbon cable is tested for broken wires at first, and then it is tested normal. after careful observation of the system structure, it is found that the image signal on the tft LCD screen is led to the key board by the 40 pin ribbon cable of the main board and then connected to the tft through the 30 pin plug. after careful observation of the socket, it is found that there is white crystalline substance in the bottom of the socket.
Therefore, it is highly suspected that the cause of the failure is here. because the socket can't be purchased, it is dismantled, cleaned with alcohol and dried, and then 30 pin wires are carefully welded. the test machine shows normal, shut down, and it is cured with ab glue. there is no abnormality until now when it is delivered to clinical use.