Endocardial Mapping Instrument Display Circuit Board Restoration can start from inspection over the electronic components:
First of all, check the start-up of the crystal, especially the faulty circuit board in a vibrating working environment, which can easily cause the crystal pins to loosen with the inside, causing the crystal to malfunction.
After confirming that the crystal is not faulty, in order to avoid the impact of the crystal on the on-line tester, you should use test hooks to short and ground both ends of the crystal (vertical crystal). If a special crystal (horizontal) is used on the board under test, it is best to temporarily solder the crystal off the board.
There may be socketed devices such as CPU, EPROM, GAL, etc. on the faulty circuit board. The failure of such devices should be eliminated first. Comparison method: through the special test functions of the online tester, such as LSI, EPROM, GAL test functions, etc .;
Or use the VI curve comparison method, such as testing special CPU devices. The replacement method is more simple and straightforward, that is, the CPU, EPROM, GAL and other devices with sockets on the faulty circuit board are inserted into the same position of the PCB board one by one, and the boot is verified to work normally.
Generally, do not insert the CPU, EPROM, GAL, and other components from the well functional printed circuit board to the malfunctional PCB circuit board when troubleshooting for the test on the machine, so as not to damage the devices include CPLD, MCU, DSP with embedded program, or the heximal from flash memory has been extracted from Microcontroller on the good board because you don’t understand the fault condition of when the circuit board has been broken.
