PC motherboard component level repairs
Tom MacIntyre
like to know if there is a specific approach that works best. I am
thinking ESR the caps, and check diodes for shorts, maybe a few
voltage checks...any other hot tips? Thanks.
Tom
Wild Bill
in-circuit reliability for the readings. Visual examination can be tricky..
it's easy to overlook a lot of faulty connections, or a burned open surface
mount resistor.
A particularly critical location would be the hot area around the on-board
voltage regulation section.. looking for evidence of any overheating of
individual components and connections.
Factory soldering should be very closely examined, even more closely than
most consumer entertainment equipment. Any grainy or dark looking solder
should probably be vac-desoldered and redone. Liquid rosin flux works well
for creeping into the thru-hole eyelets.
A fairly common fault on dead used boards is a place where someone has
slipped while inserting a mounting screw.. there may be a skid mark showing
where the screwdriver tip skidded across the board surface.
If the slip has displaced any of the large QFP pins, they can usually be
repositioned and reflowed with liquid flux and a fine tip.
There might also be broken/cut traces from these accidents.. repairing
traces that small can be a big challenge.
As a check of QFP pin soldering integrity, i use a sharpened hardwood swab
stick to drag over them (with moderate pressure), to see if they're all
secure.
cheers
WB
...............
Tom MacIntyre wrote in message <3a21080e...@news.wolf>...
CClay51032
Tom MacIntyre
>Some times they have open fuses that look like a resistor.
The same trick is used in monitors at times... :-)
Tom
Andy Cuffe
>
> I know that a few of our regular contributors here do this, and I'd
> like to know if there is a specific approach that works best. I am
> thinking ESR the caps, and check diodes for shorts, maybe a few
> voltage checks...any other hot tips? Thanks.
>
> Tom
Are you just looking for general tips, or do you have a specific
motherboard to repair? If so, what is the problem?
My MB repair experience is limited to a damaged trace when someone else
replaced a bad keyboard controller, and a bent pin on a SIMM socket. I
have never seen high ESR caps on a motherboard because they are rarely
more than 4 or 5 years old. The older ones use tantalums which don't
suffer from ESR problems. High ESR caps are probably going to be a
problem soon because most recent MBs put small electrolytics near the
hot regulators.
--
Andy Cuffe
balt...@psu.edu
Tom MacIntyre
wrote:
>Tom MacIntyre wrote:
>>
>> I know that a few of our regular contributors here do this, and I'd
>> like to know if there is a specific approach that works best. I am
>> thinking ESR the caps, and check diodes for shorts, maybe a few
>> voltage checks...any other hot tips? Thanks.
>>
>> Tom
>
>
>Are you just looking for general tips, or do you have a specific
>motherboard to repair? If so, what is the problem?
Just curiosity...thanks.
Tom