How to Restore Printed Circuit Board without Schematic Diagram

When try to Restore Printed Circuit Board in the absence of its schematic diagram, especially when this Printed Circuit Board is relatively strange to the engineer, according to previous experience, even if a veteran Printed Circuit Board restoring engineer won’t be able to fix this issue promptly and smoothly, hereby we list some of the main principles that can be followed when try to repair a one to increase the working efficiency:

First of all, monitor target Printed Circuit Board and then measure it, the tools should be applied include the multi-meter and microscopy, the good habit to handling a Printed circuit board ready to be restored is monitoring it, by using microscopy can check if there is any break-off of tracks on the Printed Circuit Board;

Restore Printed Circuit Board without Schematic Diagram

And if there is any break-off phenomenons can be found on the negative parts such as resistor, electros, transistor, diode and triode; and the most important thing is if this Printed circuit board had been restored before.

If yes then which components had been touched or moved? Is there any mis-conduct such as false soldering, cold soldering or reverse insertion, after confirming there is no such case, need to use multi-meter to test the resistance value among the power supply and ground, normally this value of resistance could be around 70 to 80 ohm, or above,

cuando se intenta restaurar la placa de circuito impreso en ausencia de su diagrama esquemático, especialmente cuando esta placa de circuito impreso es relativamente extraña para el ingeniero, según la experiencia previa, incluso si un ingeniero veterano de restauración de placas de circuito impreso no podrá solucionar este problema de manera rápida y sin problemas, a continuación enumeramos algunos de los principios fundamentales que se pueden seguir cuando se intenta reparar una para aumentar la eficiencia de trabajo:

if the resistance value is too small, only a handful or a dozen of ohm, there could be some of the components have been breakdown,

then it is necessary to find out the breakdown components from the Printed circuit boards, and the method is power on it, and feel the temperature of each one of them, and those with extremely high temperature will become suspected item.

And if the resistance value is normal, need to measure the value of each part such as resistor, diode, triode and MOS-field effect tube, switch. The purpose is to ensure the