2.5v rail loss

[mpheyse]

Product: WS-12-250-DC




Cause of Failure if interested

Code: Select all

 Tower site partially when offline, due to loss if communication with switch. Router still had HW link and all POE/Link lights were still on, on the switch


Rebooting the switch stops just after the front power LED comes on. No fan startup sequence, no POE or Link lights.

Programed a second unit with a Config backup, tested dry at desk. Replaced with switch in field.

Blows 7.5 Amp fuse-ed supply.

Unplugged all tower radios, only connect two local devices (local phone, and router) switch works fine.

Plug first cable (#1) into port 1. Arc-ing noises and burning smell. Remove cable. Switch is still powered up. plugin all other ports. Still powered up but is non functional

Reboot switch

Stops boot process at font light, no fan sequence.... failure identical to original switch


I seem to have lost the 2.5 volt rail on the main board.

Both switches are out of warranty (19' and 20' vintage)

They both go through the PSU boot sequence (LED) and then Turn on the Front Power LED, and the Fan jiggles.


Internal PSU is putting out 50.1 volts, so I don't think a replacement PSU is the fix. Please correct me if I'm wrong


The Main board is putting out 24v rail, and the 3.3v-D, 1.8v-D, 1.0v-D rails but I get nothing on the 2.5v-D rail.

My assumption is that the "-D" is a digital supply rail and the Buck converter [U20] that seems to make 2.5v from the 3.3v-D rail seems to be busted.



Is this correct; that the loss of 2.5v-D would halt the boot process? or is the 2.5v rail startup later boot process than I'm getting to?

Is there a repair process for this type of failure? (there are no replacements to BUY!!!)

[thomas]

if you blew it up with port1, pull the diode packs U115/U114 since those can pull 2v5 down. likely won't do squat though, you probably fried the SOC. not sure if netonix replaces those (I think that's a "no fix" state for them), but I can slap a new SOC on there for you.

in the future, if oyu have anything funky going on, don't plug into a live port on a netonix, plug it in while the switch is unplugged or poe disabled on the aforementioned port.

[mpheyse]

Both are WS-12 Rev J Which only have thru U104 (and 103 isn't populated) so there isn't a U115/u114. Both have the same 'injury' and the same symptom.