Quote Originally Posted by Matthias View Post
I have no idea what this can be - please measure the voltage, we must consider that some of the L-ports died for some reason. Only after getting the measurement results I can do some diagnostics here.

Recently we had a case where defective electronics of the Tunze driver blew up some of our 1-10V circuits. Very weird was in that case that the problem in the Tunze driver occured not permanently, most time it worked well.

PS: A reference to Ultimate Reef is ok, this is an open and free forum.
Tunze is the only common point here - Ports L3/4 were also used to control Tunze pumps before I re-configured them for LED's , moving the pumps onto the expansion card ports 5/6 and 7/8 ...

Sorry for my ignorance but do I measure the voltage between

1 +12v and 2/5 depending on channel or 3 GND and 2/5 I am assuming the +12v but don't want to do any damage
Also what should I expect on the On/Off channels ?

I assume the following to be correct:

1 +12V - Black
2 Dimming intensity channel 1 - Brown
3 GND - Red
4 On/off channel 1 (relay control) - Orange
5 Dimming intensity channel 2 - Yellow
6 On/off channel 2 (relay control) - Green