I have a Malibu MT600TW transformer which is not working. When it is plugged in and turned on, and I place a voltmeter across either of the A-B terminals, I get no voltage reading. An ohmmeter measurement seems to show that the A-B terminals are connected, which I assume is a problem. Could this have been caused by the terminals getting wet or something?
Testing ohms across A and B will read open circuit through transformer coil.
Testing DC voltage across terminals A and B should read 12 volts DC, and nothing less.
Transformer should make humming sound when working.
Test that receptacle has power and breaker is not tripped.
There are no repair parts for power packs, but they come with 5 year limited warranty.
For more information on Intermatic/Malibu power packs showing troubleshoot steps, replacement trippers, useful links, warranties and tips:
http://waterheatertimer.org/Malibu-power-pack-stopped-working.html
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Thanks for your help.
No, there are two A-B terminals and each one is for a different 300W circuit. The two wires for each circuit are connected to A and B (one to each). The manual with instructions can be found at
http://www.malibulights.com/PDF/158ml129...
When I check the voltage, I just place the two voltmeter leads on A and B (one on each), then I switched to the other direction just to make sure the polarity is correct.
I assume there should be 24V across these two terminals? Yes, the timer/switch is working, and the transformer is getting 120V, I checked both of these.
Thanks again.
You were right on all counts ... I was checking DC volts, and it is a 12V system not 24V. And I understand your comment about continuity through the transformer windings.
So I gotta look for another reason why the lights aren't working.
But thanks for taking the time to reply! You were extremely helpful.
I'm going too fast here. Of course, you have 12 VAC on the A/B terminals or you wouldn't be looking for another reason for no lights.
If you only have one circuit in use, maybe there is a cut wire. I would first check the continuity through the line going to the lights.
Thanks for the reply. I'm not ready to quit yet. Did you check the output on the A/B terminals and it is zero?
Sorry, one more point. There should be continuity across A & B terminals. The meter is measuring the resistance of the secondary coil in the transformer -- if you got no continuity across these termianls that would be a problem -- the coil would have an open circuit which would render it non-functional.
Please don't take offense, but did you have the voltmeter set to A/C volts?
I didn't see any electrical specs in the pdf above, but every outdoor lighting transformer I've ever seen has a nominal output of 12 volts A/C.
When you mentioned polarity, that kinda told me you were checking for DC voltage.
But, be that as it may, I assume it won't light up anything, and that is the symptom of concern -- is that correct?
I could only find the ML600TW on line.
But in any event could I get some clarification?
Are the A & B terminals for different circuits?
When you check for A and then B voltage, do you use a common terminal to do this?
Have you confirmed that the timer/switch are working and the transformer is getting 120 volts?
Charlie
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