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Thread: Archer/TP-Link VR1600V rev.1 failure ~ autopsy

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    Default Archer/TP-Link VR1600V rev.1 failure ~ autopsy

    I think this is the 2nd or 3rd one of these modems that's up and died on us. This one gave a bit of a clue it was headed this way about 6months ago, when the wifi section seemingly lost range and became unreliable (packet loss)

    Final fail state is the modem keeps ostensibly boot looping....at least, that's the impression it gives...but after further examination this behaviour was likely heat related.

    Only because I saw these things being sold 2ndhand/used on ebay and the like, I thought I'd pull this one down for a squizzy, and see if there was anything 'obvious' inside that led to the failure.


    This actually presents itself in reverse order during disassembly, but here I'll start at the heat source and layer out the (failed) thermal management stack....


    ...here we see the main network controller chip, Broadcom BCM63167VKREBG in a BGA package with base of die exposed (it's like an encapsulated flip chip design). The chip above to the right is a Zentel dram chip, but part# can't be found ; should be 128Mb/DDR3 -- I think it's a knockoff 'coz Zentel is out of JP, this thing was made in CN, and the font/zentel logo printing on the chip itself are a bit off




    As you can see, both these ICs are protected by an RF shield, so to transfer the heat from the flipchip and ram, they used thermal conductive pads adhered to the underside of the RF shield cover....




    The pink pad at the top covers the flipchip, and you can see the stains on the metal where whatever liquid component that's in the pad material itself, has started separating from the pad material and flowing out and away from the pad...




    On top of the RF shield cover, is another large thermal transfer pad to help transfer the heat into the large metal heatsink (passive). It's not really apparent in the above shot, but that same oily, liquid component of the pad material has oozed out of the pad material...which in this shot is pretty close to compacted pink talcum powder.....but in this next shot....




    ...you can see the large oily stain on the heatsink around the pad, and the little pile of pink dust/powder I was able to sweep up with my finger tip 8)



    So looks to me like thermal transfer interface failure is the prime culprit, so my advice is don't waste your money on these in the 2ndhand market, they'll be headed for the same demise.

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