what is the first step to troubleshoot the repair of any machine?

The first step in troubleshooting a system complex issues: What is happening ? if you Knew what happened is sufficient the50% problem is solved.
next50% solution is depend upon your experience.
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I think that the first step is the testing of mechanical or manual way to find out where the malfunctions mean briefly identify the problem is the first step for the maintenance of any machine.

Before troubleshooting any problem, You should have clear knowledge about that machine hardware and its working procedures. To make sure the source of the fault, you have to divide the Issues in smaller parts. For example-

1. Does the trouble raised from the power source?

2. Does the problem raised from hardware or software?

3. If hardware, in which conditions does the fault appear?

4. If software, which software or command or file generates the problem?

5. It may be caused by over heat. If so then how long the machine can run or how much load can the machin bear before the problem arise?

6. You may need to dismantal the machine and run it with minimum hardware that it can start with. If machine runs well then add one hardware and test again. Carryout the same procedure untill the problematic hardware is diagonosed.

Hope this will help you most.

بداية السلام عليكم ورحمة الله وبركاته , أما بعد : اتوقع انك بتكي عربي , لذلك رح اكتب بالعربي تفادياً للأخطاء الاملائية ولحتى يصل كلامي بشكل أوضح ,, كما في الامتحانات فهم السؤال نصف الحل , كذلك هو الأمر بالنسبة للحاسبات , فهم المشكلة (تحديد ماهية العطل أو المشكلة , أو بمعنى آخر ما المشكلة التي نبحث عن حل لها ) هو نصف الحل بعد تحديد المشكلة أو العطل الذي يعاني منه الجهاز , > إذا كانت مشكلة واحدة نبحث لحل هذه المشكلة > وفي حال أنه يوجد أكثر من مشكلة بديهياً نبحث عن حل المشكلة الأكبر فالاصغر أما بالنسبة لتحديد سبب العطل فالاسباب كثيرة ومن الصعب أن احصرها لك , ولكن خلال مشوارك ومع القليل من البحث ( الانترنت مصدر هائل للمساعدة ) ستتعرف تدريجياً على اعطال الاجهزة والحلول المناسة لكل عطل مع تمنياتي لك بالتوفيق , أتمنى أكون فهمتك كويس وساعدتك بجوابي , والسلام عليكم ورحمة الله وبركاته

My Dear Brother Yaseen, A.o.a Its totally depend on the machine what kind of machine you are going to troubleshoot....? Are you going to troubleshoot Computer system, Digital Camera, Water Motor, CCTV Camera, Motor Vehicle etc...1st step -----> it depends upon your experience about the machine you are going to troubleshoot......
:) -----> If Computer System then according to my experience check first the Power Cables connected to the system are properly connected or not if so then start your troubleshooting step by step according to your experience.
-----> From my point of view Steps are given bellow.1.
Power Cables2.
Main Direct AC Power3.
Power Button of Computer System4.
Check all the Power Connection of the Computer System.5.
Power Supply6.
Fans.
These all are primary and major steps to troubleshoot the computer system machine.....
All other machines are also needs the power in the form of direct AC current or batteries.....1st step for all those machine is to check the Current and voltages of the machine is available or not and then start your troubleshooting according to your experience.....
:) I Hope this Information will be beneficial for you......
:) Thanks and Regards Syed Waqar Ali Shah.......

UNPLUG IT FROM THE ELECTRICAL CONNECTION.

First Step will be to understand the nature of the problem, If the machine is completely Dead than check the power supply to the machine.
Check that the connectors are not lose or unplugged.

the first step is to check the power inlet to see if there is power in the m/c or not

Better to know first about what happens from the operator then gather documentaries like, schematics, equipment history of operation like parameters, and manuals.

first step is to check supply of power in hard plus rom plus main power supply of board when you check these other problem will be check after these like ram is not working they will give some sound also when hard did not responce then you check board supply

if the machine does not start ...
then: - Check if there is current (problem: the cable allumentation - box of allumentation - the fuse box in the allumentation).
- If the current exist: remove the CPU, RAM, all HD and CD ,DVD cables and starter Machine (Beep sonor) - See the battery (3 volt).
- check the motherboard (BIOS ,Chipset , VGA ,Usb Card NetWork port Or card)...