ISY994i Unresponsive after power disruption

[Brian H]

A V1.5. Mine had 10uF/35V capacitors in it. That was the one I rebuilt when it failed. Used 10uF/35V. Same for two 2443 V2.5 Access Points. That where built on the same base 2413 PLM main board. The PLM has not had much test time on it after rebuilding. The Access Points are still in use after rebuilding. One of the Access Points didn't work after rebuilding. I had damaged a PC run and had to add a jumper wire to fix it.

One thing to remember. When replacing C7 and C13. They are in a switching power supply. The replacements should be designed for that type power supply. A general purpose capacitor may not work well or have a short life.

[apostolakisl]

3 hours ago, Brian H said:

A V1.5. Mine had 10uF/35V capacitors in it. That was the one I rebuilt when it failed. Used 10uF/35V. Same for two 2443 V2.5 Access Points. That where built on the same base 2413 PLM main board. The PLM has not had much test time on it after rebuilding. The Access Points are still in use after rebuilding. One of the Access Points didn't work after rebuilding. I had damaged a PC run and had to add a jumper wire to fix it.

One thing to remember. When replacing C7 and C13. They are in a switching power supply. The replacements should be designed for that type power supply. A general purpose capacitor may not work well or have a short life.

I replaced the c13 10uF/35V cap with a 10uF/50v one (cause that is what I have on hand.)  The other 3 I replaced with like valued caps.  I am confident I didn't damage any wire traces or other components doing my work.  When I plug it in, the power led does not come on.  I haven't tried plugging it into the ISY since replacing c13.  But after replacing the other 3 caps I did, and it hung the ISY just the same as it did prior to doing anything (the tx light on isy would flicker and isy would be unresponsive).  Is c7 the big fat 10uF/400V cap?  I replaced that with a like rated one by nichicon that is physically much larger (but fits), though it covers the board marking so I can't see what number it is. (edit, I was able to just see around it, the big one is c3).  c7 and 13 are both replaced with 10uF/50V (c13 originally was 10uF/35v)  In total I've replaced c 11, 3, 7, and 13.  That only leaves one aluminum type electrolytic capacitor un-replaced.

[Brian H]

C8 the 10uF/16V. It is the filter capacitor for the +5 volt logic on the main board. On the output of a surface mounted linear regulator.  I suppose it may have failed. But not being stressed not a high candidate.

If you are electronically inclined. There is a basic power supply of the 2413 in the very long thread on repairing the board.  Though how much further you want to go is up to you.

You can measure the unregulated 12 volts DC on the serial daughter board. Usually around 18 volts. Ground tab on U1 the 5 volt regulator for the daughter board  is - and one of the unused pads of the F1 location. Where F1 use to provide unregulated 12 volts on the serial connector when in the older 2412S. I don't remember of hand which F1 pad was the voltage and which went to the serial connector.

V2.4 has a redesigned serial port daughter board and I don't have information on an easy set of test points.