Some Facts About
Troubleshooting And Repairing Mainboard
There are three
types of Mainboard in the market. The first one is purely using
standard components (not Surface Mount Devices- SMD) and generally
is considered old already (most probably use in the 70’s and 80’s).
Second one would be the combination of standard components and SMD
components and the third Mainboard is purely using all SMD
components (currently manufacturers producing this type of
Some repair tech
call this mainboard as motherboard while to some they called it as
cards. Once in a while I have customers came to me and showed me
the mainboard that was used in their industry such as printing,
PABX system and etc and asked for a solution. They wanted to know
whether these types of Mainboards can be repaired or not. For your
information, Mainboard can also comes from consumer electronics
products such as LCD TV, LCD Monitor, Plasma TV, Computer
motherboard and etc. There are some facts that an electronic
repairer needs to know before he or she can proceed with the
troubleshooting and repairing job.
If you want to
successfully repair any Main Board, you must get the whole system
with it. That means, you need the power supply board and whatever
boards that are connected to the mainboard. If the customer just
send to you the mainboard, it will be hard for you to repair
because you do not know the correct voltage that needs to be
applied to the mainboard and without the right voltage there will
be no signal waveform for you to check.
Of course you can
connect an external source to power up the main board, but you have
to understand that certain Mainboard would not run properly if it
did not connect to a load. For example, if you are troubleshooting
a LCD Monitor mainboard, the power supply/inverter board, backlight
and the LCD panel have to be connected in order to get the right
voltage and waveforms. Missing either one of the boards may produce
different result. Tell your customer the truth that without the
complete system, it will be difficult to repair the main
mainboard ICs are using programs to run. Some typical examples are
the ROM, Microcontroller Units (MCU) and EEPROM ICs. These ICs have
programs in it in order for it to function well. If the programs
have corrupted the whole function of the mainboard will go haywire.
It will produce weird symptom and very hard to troubleshoot and
repair if you do not have the exact program data and the
service manuals and other related information to the mainboard is
usually hard to find from the market. If you can locate the
schematic diagram, that means it can cut short your repairing time
because you will know what sort of voltages and waveforms to be
present in the testing points of the components.
Many new mainboard
are using the BGA(Ball Grid Array) ICs and the normal SMD rework
station is not suitable for removing this kind of IC. You need the
BGA IC rework station to do this job and this machine is not cheap.
Without the proper tools even though you have confirmed that the
BGA IC is the cause, there is no way to remove it. If you can’t
remove the IC, which means you can’t make the mainboard to work
equipment companies like the Huntron, Sencore, Polar, ABI and etc
have developed specialized test equipment just to tackle problems
in the mainboard. Well, of course you can do the repair job without
them, but do you know that if you have such good test equipment in
your work bench, it will definitely speed up your repairing time.
By comparing a good and a bad board in term of voltages, waveform
or even signature analysis, you can easily identify the problem.
These specialize test equipment is a big investment and if the
board that you are charging does not justify with it then don’t
invest in such expensive equipment. It will take years to recover
back your investment.
I have a repair
friend who told me that he had a Polar test equipment and a high
end Digital Oscilloscope. He used it to repair the mainboard from
the Aeroplane control tower. He replaced only a cap and charged
USD600.00 because the original mainboard price was about USD30,000!
With only few of this repair jobs, he already gained back his
investment on the high end test equipment.
Even though you have
the BGA rework station and you have successfully removed the IC,
you still need a replacement part. Without the right parts, there
is no meaning in removing the IC in the first place. If you have
good sourcing of parts for the mainboard that you are repairing,
this will guarantee the job can be done. It is better still, if you
could locate the exact mainboard that have a reasonable price.
Instead of repairing you just sell the whole board to your customer
and buy back the spoilt board and salvage the parts for future
Conclusion- I’m not
writing this article to discourage you to repair the mainboard.
These are the facts that we must accept as an electronic repairer
when we deal with mainboard. Now, if you have the total solution
for the above problems even just for a particular equipment or a
model, you or your company will stand tall over your competitors
and make lots of money in this repair field. That’s all for
this month repair article and will see you again next month. Have a
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