Cisco 1721 (17xx series) PSU pinout

Posted on 2005-03-10
Medium Priority
Last Modified: 2012-08-13
I've got problems with my Cisco 1721 router.
I suspect on the power supply. Do anyone know the pinouts for the PSU for this router?
Question by:Dragonmen
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Expert Comment

ID: 13515107
Wow, I can't find the pinouts anywhere on the 'net...the best I found was that the 1721 uses a switching psu at 5 and 15vdc.

Expert Comment

ID: 13515111
er, that should be 5V and 12V
LVL 11

Expert Comment

ID: 13520454
There is no pinout there, only I found is:

Check your power supply with electrical tester, it should give +5, +12 and -12 VDC

Author Comment

ID: 13521108
I know that this PS has +5, +12 and -12 becouse it's written below the power connector, but i don't know what are the pins for this voltage (it has 6 pins and 3 voltages).
I founded out how to discover this voltage levels on the device side - by looking at the main board (which is a 3 layer board btw)
The pinouts are (from left to right):
* * * - Ground, Ground back to psu, Ground
* * * - -12V, +12V, +5V
I repeat - from the router's side.
Yes, i know it's in reverse order in what it's told below the connector, but it's 100% this way.
I did a slight change to PC ATX PSU and connect it to this router psu connector (since PC ATX PSU has 5, 12 and 3.3V) and it worked. 1721's PSU is using 20W and i have old 200W PSU which is working great. If someone's curious about how i did find this - it's relatively easy. -12V line got to the left side of the board and i can't find where it's going since it's 3 layer board. +12V is going straight to the capacitor above connector. +5V is going to the ic's and that brushless fan above the board (which suprisingly works at 5V). 2 connections above are interconnected with one like of power switch and third is connected to the other line of power switch.

It's not my intention to give the answer to my own question, but someone could need this (you can't find this info anywhere).
Admin, please close this post.

Accepted Solution

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ID: 14040411
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