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First diagnosis steps, how to?

Sofiane

Feb 12, 2023
1
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Feb 12, 2023
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1
Hello.
I apologize if this has been asked before.
I am an electronics graduate (bachelor) so I know the basics to electronic components and how to test them, but I have no clue how I can start diagnosing a PCB or a new equipment. I know that I should first perform a visual inspection then maybe look for shorts in the primary side (not exactly sure how this can be done) but then what? How can I proceed on the diagnosis. I know am not supposed to unsolder every equipment, test it then put it back so what are the steps that you usually take and how do you usually proceed with fault detection and minimize your faults area
I also have troubles sometimes finding how some components are connected with each others as I get lost following the pcb paths. Should I be doing that and am I missing something?
Please share any advice that you could give, I would appreciate everything
 

Bluejets

Oct 5, 2014
6,920
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Oct 5, 2014
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6,920
Your query is too broad in nature due to the gazillions of electronics out there.
Comparison.....I want to build a space shuttle but don't know where to start.
 

danadak

Feb 19, 2021
767
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Feb 19, 2021
Messages
767
Generally :

1) Look for hot spots, excessive heat generation, at a component site.
2) Look for solder joint proper wicking on leads and thru hole vias.
Magnifying glass great help here.
3) Look for leakage from eletrolyte types of caps, like electrolytics.
4) Bulging caps :

1676246285044.png

5) Power rails, look for high current damage, melted copper.
6) Carbon comp R's age and change value, my experiences
typically rise to higher values.
7) Board edge connectors, look for contact oxidation.

Usually when a component fails, especially caps, they short and take out
other components in the power path. Zeners also can fail short, or change
their design V.

When powerup old gear set you supply with limited current, helps to mollify
other damage due to any shorted components on boards.

Regards, Dana.
 

Delta Prime

Jul 29, 2020
1,964
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Jul 29, 2020
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1,964
I also have troubles sometimes finding how some components are connected with each others as I get lost following the pcb paths. Should I be doing that and am I missing something?
Schematics are two-dimensional circuit design showing the functionality & connectivity between different components.
Physical constraints & requirements mean that the PCB design generally looks quite different than what is mapped on the schematics, the design includes a silkscreen layer. This silkscreen layer indicates letters, numbers, & symbols that help engineers or technicians in the troubleshooting process.

Different causes of failure can
occur in electronic equipment.
Overloading a component or circuit.
Environmental conditions extreme cold or heat.
Mechanical stresses, flexing, vibration
Subjective to heavy G-forces, dropping the unit will causes component failure
of electronic equipment.
Failure can be caused by incorrect use of the equipment.
Subject to most stress, is the power supply circuit, heat & overload is common.
Power amplifier circuits supply high power too heavy loads antennas, motors.
High density memory chips when subject to power supply voltage variations or electrostatic discharge
can be destroyed(max smoke).
Wires, cable & connectors are mechanical components that are most subject to failure.
 
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