about repair calibration modding
This section gives some general troubleshooting directions for TVs and CRT monitors based on my experience and information I found online. I am not a professional repair technician this is just based on my attempts to repair stuffs.
I took notes of the different repairs I did on this page repair-log
!! Warning !! Only attempt to repair if you know what you are doing. CRTs are dangerous even unplugged they can still carry high voltage.
When a monitor fails it means one or several components have failed. In some case repair is possible if the part is still available. In other cases repair might just not be possible (i.e. dead electron gun).
The first step is alway to identify where the issue is. The flowchart is a good starting point for troubleshooting.
For more details the website below is the absolute reference:
Sometimes in order to find the issue some measurements needs to be done with the monitor turned on. Extreme caution is needed due to the high voltage in some areas. Also test points are not always easily accessible and some creativity is needed to perform the measurements.
If available, the Service Manual can be of great help as well. Usually the schematics contains two some reference voltage to observe at specific location and drawing of shape of signals. Most of the time looking at voltage with a multimeter is sufficient. When this does not reveal any issue, then using the oscilloscope and looking at the shape of the signals is needed.
Components can be checked individually to see if they still have correct value. Electrolytic capacitors are known to go bad over time but other components might also have issues. Once again the service manual is useful to know components and their exact value.
The first thing to do is a visual inspection to see if there is any trace of over heated or burned components. Another point of attention is electrolytic capacitors: check for domed, or swollen top, sign of leakage.
Diodes and resistors can most of the time be tested in circuit. Capacitors can be checked with an ESR meter. This is not the silver bullet but it can help to find bad caps. In case of doubt remove it and check its capacitance.
When replacing capacitor, be careful to respect the temperature rating. Usually caps in hot area have higher temperature rating (105C). Voltage of the replacement cap should be at least equal to the original voltage rating. Using higher voltage is fine.
Another common issue is cold solder joins. Reflowing points (adding some heat and fresh solder) can solve some issues.
Most standard parts can be found from online mega shops like Mouser Electronics. More specific parts like flyback transformer can be found with Donberg Electronics. Ebay is also an option for some parts hard to find.