Nothing was working so I went to reset the ISY manually and saw that the blue PWR LED was blinking or flashing.  I think it was the way that it was blinking that made me suspect the power supply.

The LED would get brighter, but when it got near full brightness, it would shut off.  This is symptoms of the over current limiter in the power supply kicking in.  Did something fry in the ISY?

1. Measured open circuit voltage of the power supply: 5V. 

2. Measured power supply with load.  I took the back off the ISY and measured the voltage at the power supply jack:  bounced up to about a volt at the same frequency as the LED

3. Measured power supply with load of 25ohm resistor (200mA) 0V.  Yup the power supply was dead.

4. found another 5V power supply with matching plug (checked polarity)  All is working again

Suggestion.  Since the power supply is 5V@500mA,  why not power with USB power supply?

You are not alone.

There are a few messages here where the power supply was failing. I have had a few myself. 5V 500mA, 5V 1A. My ISY26, ISY99i and presently sold ISY994i.

The ISY994i has a wide range of voltages it can use. Message here indicated 5V DC  to 30V DC.  UDI  is presently selling a 12 Volt 1A replacement. On their direct sales page.

My thoughts are 500mA maybe cutting it close. If you have an added board like Z-Wave.

 

Edited September 8, 20205 yr by Brian H

Thanks for the tip on the 500mA, I do have a Z-Wave board.

I cut the cable off of the failed supply and cannibalized an old USB cable and made them into a USB power supply cable.  I'm using one of my 1A USB power plugs.  All seems good.

I didn't realize how much I depend on the device!  "Ohhhh, you don't know what you got 'till it's gone ..." [musical icon here]

13 hours ago, Old Surfer Dude said:

I didn't realize how much I depend on the device!  "Ohhhh, you don't know what you got 'till it's gone ..." [musical icon here]

Truth spoken. 

My ISY was recently disconnected for 12-ish hours due to some remodeling we are doing.  I actually planned to have it offline for several days, but after just a short time ran a temporary Ethernet cable across the floor so I could hook it back up.  You really don't realize the real-life dependencies created until they don't work.