Maintenance experience and principle:
Repeat the failure in person (if it can be repeated), not trusting the user or the third person's dictation or restatement.
Observe carefully, not trusting the user's dictation, especially the restatement of the third party. Some operators will say that the instrument themselves suddenly... I didn't move anything, and so on and so forth. The engineer will handle it properly.
First external, then internal.
Don't be so ready to open the shell. It's not an old hand to be able to open up a business without initial judgment and exclusion. Looking to open the shell to see where there are broken lines or obvious faults is purely a chance, even if good luck cannot always be the case.
About 50% of the failures are caused by external environment, operation, cleaning, etc. How long does it take to turn off the phone? Is the temperature difference very large?
Is the placement of the instrument close to the elevator? What other instruments are in use near the instrument? Is the computer setup correct? And so on.
Power first, rear host; Attachment first, rear host.
Check whether the power supply is stable, the load is too heavy, the ground line is good, the electrode and other accessories are good and normal, the interface is correct, etc.
Make full use of all kinds of buttons, display screens, operations, or maintenance programs on the instrument panel to eliminate them. This requires an extremely familiar structure. (important steps)
Knowing the user's operating habits, the structure of the operator and the level of the operation, the economic situation in the section will also be helpful to the maintenance.
If you can infer how clean maintenance is, whether there is an idea to update (otherwise you won't say anything). If I run into a blood count, former several engineers countless times maintenance, continuous two years, has also changed in the new machine, but less than half a year and repeated failure, trouble.
When I took over, I had to call the doctor. The doctor answered yes, and then pressed the switch. After pressing, press again, the machine restarts. The original instrument has the screen protection function, the section of the room is not a special person to hold the use, the user USES good to walk, after the user sees the screen dark, open the switch. How is it possible to switch the power supply hundreds of times per day?
After the repair, I wrote a note to the instrument, indicating that if the screen is dark, press any key at random and turn on the power switch. This is no longer the case.
It is not easy to replace the components and the boards and pipes of the original instruments, because some components are related to the board and software data. It is more difficult to reduce the source of the fault by changing the board and the parts, otherwise, it will be more difficult to recruit a migrant worker.
When necessary, the instrument or engineer should take the responsibility and carry the "black pot". If the responsibility is in the office or the user, it will be harder to deal with later. For all sorts of purposes, there will be some people who intentionally fail. Best: the bell should ring the bell! Otherwise, it will take time.
It's not easy to fix a device, especially the old one. It's too easy to screw up a device. There's no need for knowledge.