WS 12-250-DC Port Power Cycling Issue

[rkelly1]

Chris et al -

I have a WS 12-250-DC switch that started cycling power on different ports randomly. It's out of warranty so you won't receive it for an RMA any longer.

We ran through the switch bench testing and one port shows 49v all the time, two others shows 19.86+/- when POE off and 24v POE on, and 49 when 48v POE is on.

Other ports seem to be ok with floating voltage when POE off ranging from .011 to 2.7.

Can a power supply board (purchased by permission) fix this? Or any other boards avail to fix it? Or trash?

Thx,
Rob

[rkelly1]

Any input Chris/Netonix team?

[sirhc]

Chris et al -

I have a WS 12-250-DC switch that started cycling power on different ports randomly. It's out of warranty so you won't receive it for an RMA any longer.

We ran through the switch bench testing and one port shows 49v all the time, two others shows 19.86+/- when POE off and 24v POE on, and 49 when 48v POE is on.

Other ports seem to be ok with floating voltage when POE off ranging from .011 to 2.7.

Can a power supply board (purchased by permission) fix this? Or any other boards avail to fix it? Or trash?

Thx,
Rob

That 1 port 49V then that port was damaged, 48V MOSFET is stuck ON, current sensor is also probably fried for that port.

Do not know if the power supply is damaged or not?

"Usually, as in 99%" of the time this type of damage is caused by transient AC current which is most often ground current caused the voltage to be greater than 80-90V on each side of the current sensor and popped it which caused a cascade damage to the MOSFET usually also 48V MOSFET now stuck in the ON position so if the device that was on that port was 24V it got fried and created a dead short which further damaged the switch board.

Since March of 2019 we improved the design by removing some center tap filter CAPs that were designed to reduce noise on the Ethernet line but provided multi path for AC current which allowed the current traveling at the speed of light to reach each side of the current sensor at the same time and since AC current even ground current is either 120-240V this exceeded the current sensor range of 80-90V differential on each side which resulted in the damage. Now this improvement in 3/2019 improves the switches ability to handle transient AC current but is not 100%.

Now this port could also have been damaged by a shorted cable, wrong POE option and so on, there is no real easy way to tell unless when you inspect the current sensor on that port, if the current sensor has no visible damage and if you remove it and test it is OK then the damage was most likely due to a shorted cable or wrong POE option or the device being powered died and shorted.

But NO a new power supply would not fix this, a new switch board "MAY" if the power supply is OK.????
https://netonix.com/replacemet-parts/ws-12-rb.html



Make sure AC ground rods bonded to tower ground rods and add a new 1 or 2 electrical service ground rods to prevent future ground current damage.