PDU AP7921 Internal power supply #2 fault.

[BillP]

Hi , I am using AP7921 and experencing the problem like the subject. Can you please tell me what meaning it is? Is this unit faulty?

[BillP]

Thanks for the reply.

Sorry I wrote the wrong part number .

Please see the following info of this unit.

Model Number: AP7951
Serial Number: ZA0703012622
Hardware Revision: B2
Manufacture Date: 01/20/2007
MAC Address: 00 C0 B7 2D CE 6C
Management Uptime: 14 Days 2 Hours 9 Minutes

This issue occured with firmware 2.7.4. After upgrading firmware to v3.3.1, it was gone for 2 days. Now this issue happened again.

[BillP]

Hi Ann,

Please upgrade to the latest fw, v3.5.5.

http://www.apc.com/tools/download/software_comp.cfm?sw_sku=SFRPDU355&id=55&family=70&part_num=AP7951...

Keep an eye on it, let us know if it comes back again. If it does, we'll need to gather the events, data, and config logs.

[BillP · Accepted solution]

Hi , I am using AP7921 and experencing the problem like the subject. Can you please tell me what meaning it is? Is this unit faulty?

[Roeller]

On the internet are various sources how to repair this.

[Roeller]

I had the same problems with some Zero-U Rack PDU's (7951, 7952, 7953).

Since the warranty ended on these units, there is only one thing you can do...

After looking at the problem I found the following:

In most of the units, there is a CPU part (near the ethernet/serial port) which holds a Lithium BR2032 battery. This was still fine after >10 years for me.
The CPU, It's universal. It sends it's data on a BUS network which has the relays for the sockets.

Mostly the CPU and the BUS are fine.  The thing that breaks is the internal Power Supply (PSU).

It has a PSU based of 2 parts, which are exactly the same. I saw that the 47μF 400V capacitors were bulky, so I measured the capacity... dead..  I first replaced one (but then the fuse in my house blew and the other one was bulky too).  SO finally I replaced the two capacitors by part: Panasonic EEUEE2G470, Ø16x25mm.

Then it worked great and can continue for another 15+ years!

TLDR: Replace the 47μF 400V capacitors by Panasonic part: EEUEE2G470, Ø16x25mm (need soldering). It's a typical repair after 10-15 years in which the capacitors get old.. dry.. get warm.. bulky.. dead...