# Replacing LMS7002M on LimeSDR USB

**URL:** <https://discourse.myriadrf.org/t/replacing-lms7002m-on-limesdr-usb/1739>\
**Category:** Uncategorized\
**Created:** [26 September 2017 06:04 UTC](https://discourse.myriadrf.org/t/replacing-lms7002m-on-limesdr-usb/1739 "2017-09-26T06:04:22Z")\
**Posts on this page:** 13\
**Page:** 1

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**Author:** ![brendanthebig](https://yyz2.discourse-cdn.com/flex034/user_avatar/discourse.myriadrf.org/brendanthebig/32/1475_2.png) [@brendanthebig](https://discourse.myriadrf.org/u/brendanthebig)\
**Post date:** [26 September 2017 06:04 UTC](https://discourse.myriadrf.org/t/replacing-lms7002m-on-limesdr-usb/1739/1 "2017-09-26T06:04:22Z")

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I seem to have damaged the RX input on CH A of my LimeSDR. How hard would it be to replace the LMS7002M IC. Is it worth it or should I just put up with RX on CH B only for the time being ??

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**Author:** ![brendanthebig](https://yyz2.discourse-cdn.com/flex034/user_avatar/discourse.myriadrf.org/brendanthebig/32/1475_2.png) [@brendanthebig](https://discourse.myriadrf.org/u/brendanthebig)\
**Post date:** [26 September 2017 06:27 UTC](https://discourse.myriadrf.org/t/replacing-lms7002m-on-limesdr-usb/1739/2 "2017-09-26T06:27:09Z")

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How much would it cost for a replacement chip ?

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**Author:** ![andrewback](https://avatars.discourse-cdn.com/v4/letter/a/22d042/32.png) [@andrewback](https://discourse.myriadrf.org/u/andrewback)\
**Post date:** [26 September 2017 08:24 UTC](https://discourse.myriadrf.org/t/replacing-lms7002m-on-limesdr-usb/1739/3 "2017-09-26T08:24:12Z")

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Probably not that easy, unless you have the right tooling. Someone else who has had a go at DIY QFN replacement may be able to better advise. DigiKey stock the RFIC.

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**Author:** ![modimo](https://avatars.discourse-cdn.com/v4/letter/m/48db29/32.png) [@modimo](https://discourse.myriadrf.org/u/modimo)\
**Post date:** [26 September 2017 08:37 UTC](https://discourse.myriadrf.org/t/replacing-lms7002m-on-limesdr-usb/1739/4 "2017-09-26T08:37:17Z")

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Check if all inputs are damaged. For some reason my LimeSDR has half of RX1\_W input damaged. Probably one pin of differential pair is damaged or badly soldered. Problem persists from the beginning. Signal level is 10dB smaller than RX2\_W. Although one input is damaged other ones are working properly. RX1\_L RX1\_H have the same level as RX2\_L and RX2\_H.

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**Author:** ![afiskon](https://yyz2.discourse-cdn.com/flex034/user_avatar/discourse.myriadrf.org/afiskon/32/1131_2.png) [@afiskon](https://discourse.myriadrf.org/u/afiskon)\
**Post date:** [26 September 2017 10:39 UTC](https://discourse.myriadrf.org/t/replacing-lms7002m-on-limesdr-usb/1739/5 "2017-09-26T10:39:42Z")

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It would be not easy unless you already have an experience of soldering QFN packaged ICs. However if you managed to find a replacement chip some guy in local smartphone/laptop repairing service could probably solder it for you. Or yes, just use only CH B.

If I may ask, what happened, how exactly did you damaged a chip? Any advice how to avoid the same problem?

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**Author:** ![afiskon](https://yyz2.discourse-cdn.com/flex034/user_avatar/discourse.myriadrf.org/afiskon/32/1131_2.png) [@afiskon](https://discourse.myriadrf.org/u/afiskon)\
**Post date:** [26 September 2017 10:43 UTC](https://discourse.myriadrf.org/t/replacing-lms7002m-on-limesdr-usb/1739/6 "2017-09-26T10:43:00Z")

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> [@brendanthebig](#):
>
> How much would it cost for a replacement chip ?

~ 110 USD [LMS7002M Lime Microsystems Ltd | RF and Wireless | DigiKey](https://www.digikey.com/product-detail/en/lime-microsystems-ltd/LMS7002M/1434-1003-ND/5012880)

Frankly for similar price you may consider to buy a brand new LimeSDR Mini instead.

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**Author:** ![brendanthebig](https://yyz2.discourse-cdn.com/flex034/user_avatar/discourse.myriadrf.org/brendanthebig/32/1475_2.png) [@brendanthebig](https://discourse.myriadrf.org/u/brendanthebig)\
**Post date:** [26 September 2017 23:27 UTC](https://discourse.myriadrf.org/t/replacing-lms7002m-on-limesdr-usb/1739/7 "2017-09-26T23:27:45Z")

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I leave my LimeSDR powered up and with antennas connected all the time. I believe that static build up on the longwire antenna I had on RX1\_W did the damage as the LNA on that input is no longer working. The LNA on RX1\_L is still working but the signal levels I am receiving are way down on what they were before the damage. I suspect I have blown the LNA on RX1\_W and also done some damage to the ic circuit after the LNA.

I recommend people use some sort if input protection if using antennas that may build up a static charge.

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**Author:** ![brendanthebig](https://yyz2.discourse-cdn.com/flex034/user_avatar/discourse.myriadrf.org/brendanthebig/32/1475_2.png) [@brendanthebig](https://discourse.myriadrf.org/u/brendanthebig)\
**Post date:** [26 September 2017 23:30 UTC](https://discourse.myriadrf.org/t/replacing-lms7002m-on-limesdr-usb/1739/8 "2017-09-26T23:30:14Z")

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I do have some experience replacing SMD ic’s but not QFN type. I might practice on a few old video cards etc before contemplating replacing the LMS7002. I’ll just use CH B for now.

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**Author:** ![brendanthebig](https://yyz2.discourse-cdn.com/flex034/user_avatar/discourse.myriadrf.org/brendanthebig/32/1475_2.png) [@brendanthebig](https://discourse.myriadrf.org/u/brendanthebig)\
**Post date:** [26 September 2017 23:31 UTC](https://discourse.myriadrf.org/t/replacing-lms7002m-on-limesdr-usb/1739/9 "2017-09-26T23:31:56Z")

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Thanks for the reply Andrew. I might look into getting the chip once I have practised enough on some old video cards (removing, cleaning and refitting ic’s). I’ll let you know how I go if and when I get around to it.

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**Author:** ![mzs](https://yyz2.discourse-cdn.com/flex034/user_avatar/discourse.myriadrf.org/mzs/32/2678_2.png) [@mzs](https://discourse.myriadrf.org/u/mzs)\
**Post date:** [26 September 2017 23:41 UTC](https://discourse.myriadrf.org/t/replacing-lms7002m-on-limesdr-usb/1739/10 "2017-09-26T23:41:10Z")

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The LMS7002M is aQFN 261-pin package (BGA), not an easy part to remove without the correct tools and a lot of experience and not an easy part to replace without damaging other parts. It is not impossible, just at the high end of extremely difficult.

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**Author:** ![brendanthebig](https://yyz2.discourse-cdn.com/flex034/user_avatar/discourse.myriadrf.org/brendanthebig/32/1475_2.png) [@brendanthebig](https://discourse.myriadrf.org/u/brendanthebig)\
**Post date:** [26 September 2017 23:42 UTC](https://discourse.myriadrf.org/t/replacing-lms7002m-on-limesdr-usb/1739/11 "2017-09-26T23:42:52Z")

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I like a challenge 😁

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<div class="post-metadata">

**Author:** ![mzs](https://yyz2.discourse-cdn.com/flex034/user_avatar/discourse.myriadrf.org/mzs/32/2678_2.png) [@mzs](https://discourse.myriadrf.org/u/mzs)\
**Post date:** [26 September 2017 23:54 UTC](https://discourse.myriadrf.org/t/replacing-lms7002m-on-limesdr-usb/1739/12 "2017-09-26T23:54:10Z")

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There are videos of people doing similar work on other board on youtube which may help a tiny bit. But it is not easy, if it was not a $100 BGA replacement part, I’d probably give it a try though.

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**Author:** ![brendanthebig](https://yyz2.discourse-cdn.com/flex034/user_avatar/discourse.myriadrf.org/brendanthebig/32/1475_2.png) [@brendanthebig](https://discourse.myriadrf.org/u/brendanthebig)\
**Post date:** [26 September 2017 23:59 UTC](https://discourse.myriadrf.org/t/replacing-lms7002m-on-limesdr-usb/1739/13 "2017-09-26T23:59:26Z")

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By the time I take into account exchange rate and postage, I’ll probably be looking at about AU$150 or so.  
I have watched a couple of BGA replacement videos and I feel that with a bit of practise, I should be able to do it.