topic flaky KVM issue in Servers - General

flaky KVM issue

Charlie Hawkins2 — Mon, 01 Jun 2009 13:36:24 GMT

I have a 2 KVM switches and both are doing the same thing on the same/or several racks. The KVM works fine for about 5 mins, then suddenly the lines are bouncing, flaky and blurry. The colors also go crazy when trying to navigate to different machines, even with the same resolution. I have also tested the LCD to several machines and it appears to be fine. The weird thing is, I can move both KVM's to other racks and they work fine. Someone mentioned that there may be a frequency issue going on? i have 4 dl360's above and below, and 2 dl580's @ the bottom rack. There is 1u between the dl 360's above and below. Anyone familiar with this?

Re: flaky KVM issue

Charlie Hawkins2 — Tue, 02 Jun 2009 17:11:17 GMT

It appears to be some type of radio frequency or something. I've tried 3 working kvm's on this rack @ the same spot, 5x dl360's above the kvm & lcd, 4x dl580's. anyone familiar with a similar issue would be great.

Re: flaky KVM issue

PDP-Fan — Fri, 07 Oct 2011 10:00:31 GMT

This sounds like a defective power supply inside the KVM switch itself. I repaired several of those... it's always the elektrolytic capacitors on the power supply that fail. Causing a unsmooth DC voltage and a shaky, blurry picture. It typically takes a while until the caps become warm... as long as they are cool, they cause no problem.

Disconnect the unit from mains, open the cover and look at the power supply. Most likely you will find some bloated capacitors. Replace ALL capacitors of the power supply (or find someone who can do that) also those that are looking ok, they may be bad too.

EDIT - I just read the second part of your post.... this could also be caused by a bad earth connection of one of the attached servers or screens. If you have a voltmeter do this:

Unplug all connections except the mains cable from the KVM Switch.

Measure AC voltage between the metal shield of the connectors of KVM and cable from server.

Reading should be zero to a few volts. If it is more than maybe 10-20V there is a problem

Check this for each connection separately.

Do you have servers from different racks connected to this switch?

- measure AC voltage between metal parts of the two racks.

- if it is more than 10-20V check earth connection of the racks.

- Maybe an additional grounding link between the racks could help.

If you are unsure with these electrical things, get an electrician to do it.