Hello! Oh, when I closed plastic case of my mikrotik 751u-2hnd i damaged capacitor C36 near the DC-DC stepper chip U3 and capacitor dropped out from its place. I soldered it again, turned on device, all work, but signal of wifi card become too worse. Now, it can work only in few meters even on 24dbi=( Where i can get schematic diagram of the device? PS. Sorry for my bad english=)
Why you open the case?
It could be possible that the wireless amplifier is burned down. we don’t provide schematic diagrams.
Why you open the case?
Because engineers of mikrotik corporation doesn’t want to make version of routerboard 751/951 with RP-SMA connector. It’s not logical for device family, which popular for powerfull home connection. MMCX pigtail is too difficult to obtain in small cities, it costs 15+$, it losses contact, and RouterBoard costs 60-70$) RouterBoard is great, but MMCX is evil for private using. So i installed RP-SMA connector.
On other not mikrotik forums i got same answer- that wifi amp can be dead, reason of this- not loaded ant output on 24dbi power…great hardware protection=) Obviously, schematic diagrams is top secret, although any interested engineer can do reengineering if he needs…It’s a pity 
It seems that now i must search amp in china…or throw it in the trash 
=))
For each purpose there is other model of RouterBOARD. You tried to make it into something else and failed. I’m sorry about that, I hope the next time you will choose a more appropriate device for your needs, where you don’t need to solder anything.
Probably this is why the components are broken…
Actually I am not sure what was the idea, because RB951 also doesn’t have MMCX connector 
yes, 951 doesn’t have mmcx, but it has PCB tracks for two external MMCX socket. You should resolder only two capacitors for using with external antenna. I placed RP-SMA on two routers 751U-2hnd model. First 751 router work great with placed RP-SMA, second damaged in proccess…and i dont know why=(
Probably it’s big mistake of mikrotik corp to making 951 only without any external sockets. Hardware power is amazing. It for home and office sectors, so model with 2 MIMO external RP-SMA socket is the best way to make this model as default in home sectors, not any poor TP-LINK or D-LINK. Device of my dreams is 951 with two external 5dbi RP-SMA antenna. It will be universal for indoor use or outdoor in small ranges with external antenna…(if i needed to cover <250m with wifi). I hope, after few years mikrotik will make it=) Plastic case has already holes for ext. antenna, it has PCB tracks for it…what mikrotik waiting for…i dont know…