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cdiggity
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751U 2HnD all LED flashing in unison including power PWR

Wed Dec 14, 2011 9:11 pm

I have a routerboard 751U 2HnD that has been out of the box for less than 24 hours. All of the LEDs are flashing on and off in unison, including the PWR and ACT lights.

I was using it when the SSID disappeared, and now I can't get any response from it at all by wireless or by LAN. the power supply voltage is 12.08V. the power supply is fed from a 1kw pure sine wave inverter with the only other load being an ethernet switch which is functioning correctly.

what does this mean when the lights all flash on and off together?
 
ronwk
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Re: 751U 2HnD all LED flashing in unison including power PWR

Mon Dec 26, 2011 8:01 pm

i have the same problem
 
cdiggity
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Re: 751U 2HnD all LED flashing in unison including power PWR

Wed Dec 28, 2011 12:23 am

ronwk,

my unit which was doing randomly started working less than 24 hours later. Mikrotik support advised me the unit was defective and to return it to the distributor I purchased it from. The distributor and I haven't sorted out exactly what to do yet. I certainly can't trust the unit in a deployment, but there doesn't appear to be anything wrong with it at this time.

All I can do is keep it close to home and possibly send it back, although the unit is probably not worth the hassle or the shipping.
 
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normis
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Re: 751U 2HnD all LED flashing in unison including power PWR

Wed Dec 28, 2011 12:51 pm

contact seller for immediate replacement of these devices
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pablo
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Re: 751U 2HnD all LED flashing in unison including power PWR

Fri Jan 06, 2012 9:54 pm

I am also experiencing the same problem. Distributor is telling me to repair via netinstall but doesn't look like RouterBOARD is looking for Netinstall server as lights are flashing no matter. Do you have more info as to the cause of this problem so that I can share it with the dealer?
 
ddejager
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Re: 751U 2HnD all LED flashing in unison including power PWR

Sat Jan 07, 2012 3:31 am

I had one 751U exhibit the same symptoms. I plugged in a different powersupply (one that came with a 750, which has a slightly larger current capacity and is 24v instead of 12v) and the problem went away. (The 751U will work with an input voltage up to 30 v.) It could be that you have a marginal powersupply or your board does not run well at 12 volts.

Interestingly after that one powerup with 24 volts, I went back to the orignal powersupply and the 751U has been working well for 2 months now (though the wireless performance is not very good).
Last edited by ddejager on Sat Jan 07, 2012 8:18 pm, edited 2 times in total.
 
pablo
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Re: 751U 2HnD all LED flashing in unison including power PWR

Sat Jan 07, 2012 7:30 am

Thanks ddejager. Tried another power adapter that could delivery more amps and it worked! But after digging through the forums a bit more there are some posts from Mikrotik support that suggest that it's a defective unit and not the power supply. I've sent them a request for help since my dealer isn't being too helpful. I can live with it as long as I'm sure it's not a defective board!
 
tnakir
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Re: 751U 2HnD all LED flashing in unison including power PWR

Fri Apr 12, 2013 4:22 pm

I aslo encountered two 751U-2HnD boards which went flashing when connected to original power supply. After I connected it to 24V power supply it worked normally, even with the original power supplys which was problematic.

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