In order to facilitate Heidelberger SVT74 Electronic PC Board Restoration, manufacturers generally build a more general debugging and maintenance platform, which can conveniently provide the power required by the printed circuit board and some necessary initial signals.
The online measurement method mainly solves two problems.
The first is to subdivide the problems found in the previous two steps, and finally lock to the component that has the problem.
The second is through the above two steps of inspection, the problem has not been resolved, you need to find the cause of the failure through online measurement. The online measurement method is mainly performed through the following steps.
Step 1: Apply power to the Heidelberger SVT74 Electronic PC Board . Note in this step that some circuit board power supplies are not single, and may require 5V, plus or minus 12V, 24V, etc. Do not leak the required added power supply. After Heidelberger SVT74 Electronic PC Board is powered on, touch the components on the circuit board to see if there are any hot components. Focus on the 74 series chips. If the components are hot, it means that the components may be damaged. After replacing the components, check if the control circuit board failure has been repaired.
Step 2: Measure the gate circuit on the electronic PC board with an oscilloscope and observe whether it conforms to the logical relationship. If the output does not comply with the logic, it needs to be treated separately in two cases. One is that the output should be low, and the actual measurement is high, which can directly judge the chip damage. The other is that the output should be high while the actual measurement is low, and it cannot be judged that the chip has been damaged. You need to disconnect the chip from the subsequent circuit and measure again, observe whether the logic is reasonable, and judge the quality of the chip.
Step 3: Use an oscilloscope to measure the crystal oscillator in the digital circuit to see if it has an output. If there is no output, the chip connected to the crystal should be removed as much as possible before measurement. If there is no output, the crystal oscillator is judged to be damaged. If there is output, you need to reinstall the removed chip one by one, and test one to find out the fault.
Step 4: A digital circuit with a bus structure generally includes three channels: digital, address, and control bus. Measure the three buses with an oscilloscope, compare the schematic diagram by reverse engineering PCB board, observe whether the signal is normal, and find out the problem.
The online measurement method is mainly used for the comparison of two good and bad Heidelberger SVT74 Electronic PC Boards. Through the comparison, problems are found and solved. Thus, the repair of heidelberger power circuit board is completed.
