Coil beyond repair?

I have a motherboard with a slightly "roasted" coil that I'm interested in knowing if it is possible to replace and make the board work again.

Have a look at these two images:

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(component side)
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(solder side)

I know it is difficult to give a clear opinion only by looking, but what would be your guess? Could it be only the coil that's toasted, or could it be any more components? If the latter, how can I find out if that's the case?

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Rikard Bosnjakovic              |         Code chef - will cook for food
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Rikard Bosnjakovic
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Den Thu, 27 Oct 2005 08:16:04 +0000. skrev Rikard Bosnjakovic:

Before you change the coil you shoud concider to replace all the electrotytics, they seems to be bulky and leaking. Dead electrolytics are a likely reason for the high current drawn. The coil are only for noise reduction purposes, You can replace it with a jumper or any other coil with the same wire gauge.

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Best regards OZ1GNN

Christian Treldal
Reply to
Christian Treldal

There has got to be more bad than just the coil. Like the other responder suggests check the electrolytic's for shorts or replace them. Looks like you may have some collateral damage to the nearby connector.

That gray fuzzy lint-like stuff splattered around the heatsink, looks like the remains of an electrolytic cap that tried for a sub orbital launch. Look for a missing component labeled C something, and the aluminum can and rubber plug. The leads may or may not be still on the board somewhere.

For a coil of that gauge wire to burn you pulled some very heavy current. Likely as not, through a very large board trace to a regulator or filter cap which is the initial problem.

Motherboards are multi layer boards with perhaps as many as 5 layers of traces between the two surfaces you can see. There may be damage that will not be evident that will be near impossible to repair. I'd look for the obvious stuff and replace it if it's easy to do, but I wouldn't make a career out of trying to fix that board . . .

Look for a shorted power diode, capacitor, regulator IC. That choke will need to be replaced also - it looks like it may be cracked and that would alter (lower) the inductance dramatically. It is probably part of a boost or buck voltage converter. It is also close to big IC's (processor?) with heatsinks - those may also be the root cause.

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Forget the coil, look at those caps! They're blown.

There where a gadzillion motherboards made around '99-'00 that had defective caps. You got one of them. If your time is worth more than a buck an hour then you should just replace the board. Boards from that era can be had, and without the defective caps, for under twenty dollars.

Reply to
AZ Nomad

Looking at that 1st Jpg it looks like all those filter caps needs changing they are swollen.

Reply to
kip

Replace the mainboard. Not worth the time and agony.

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Reply to
Sam Goldwasser

Absolutely agreed.

Apart from the time and effort required for a repair, would anyone in their right mind want to chance their CPU in that motherboard? I know I wouldn't! Apart from all the leaking, bulging caps and possible electrolyte damage to the board, the burned coils suggests the switching regulator fets could be shorted. The CPU would be fried pretty quickly if that's the case.

Dave

Reply to
Dave D

You can rewind it, but you'll have to replace all those bulging capacitors first and clean up the leaky electrolyte, that was probably the original problem. Likely you'll have at least one shorted mosfet too which burned up the coil.

Reply to
James Sweet

The coil may well be quite critical if it's part of the buck regulator used to supply power to the CPU, it's only a few turns but they often run at 500KHz so you don't need many.

Reply to
James Sweet

May already be fried.....

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Reply to
Sam Goldwasser

Also note the burn in the power connector socket. Even the powersupply is questionable now.

I just repaired one that had 6 plus caps going bad. Had not failed but caps were domed.

Took 2 plus hours, had to use a 100 watt iron to desolder some of the caps as there were heavy ground planes inside the board.

Not worth the work if you have to order the caps (and they are special hi temp / low ESR) and the board is dead.

Seen many of these, fixed more than a few, some just for the challange.

Hugh Computer Repair center owner / head tech.

case?

Reply to
Hugh Prescott

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