# 24V AC to 12VDC converter issue



## BFHammer (Mar 18, 2018)

I posted a version of this question prior to the server crash and thought my problem was a bad converter but I got a new converter and still have the same issue so I’m posting again.  

I'm trying to install a led halo light on my PM932 mill. I picked up the AC/DC converter below from amazon and wired the 24VAC inputs one directly from the tap off the 24V side of the transformer and one from the protected side of the breaker fed from the same source. Both showed approximately 24V AC on my meter with the mill power switch off. With the mill power switch on they both read approximately 20V AC. 

Where I'm having the problem is that on the output terminals of the converter I am reading zero DC voltage.  My assumption is that I had a bad converter so I ordered another converter from a separate source and still have the same result.  I’ve double checked all the connections and even pulled both inputs directly from the transformer tap (#31) in case the breaker was causing an issue.  

I’m doubtful that I got two bad converters and I’ve rechecked everything with a separate multimeter so I’ve come to the conclusion that it must be user error.  Any help will be greatly appectiated - I don’t won’t to throw in the towel on this “simple” project but I’m ready to get me mill back together. 

Thanks,
Mark


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## jwmelvin (Mar 18, 2018)

Did you disconnect the wires from the output of the converter to make sure they are not affecting the output?


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## BFHammer (Mar 18, 2018)

jwmelvin said:


> Did you disconnect the wires from the output of the converter to make sure they are not affecting the output?



Yes.  I checked directly to the terminals of the converter - no difference in results.  Thanks


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## jwmelvin (Mar 18, 2018)

Wait, you said you took 24VAC from (1) the transformer and (2) from the output of a breaker fed by the transformer. Is that correct? When you say they "both" showed 24VAC, do you mean the voltage between them or the voltage of each referenced to a third point. It sounds a bit like the latter rather than the former. You need the two wires feeding the converter to have 24VAC between them (or 16-28VAC between them, rather).


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## mksj (Mar 18, 2018)

You would need to take power off from 30 and 31, otherwise try both sides of the power lamp. Otherwise one could use a universal 12VDC LED driver power supply that take something like 100-260VAC in and connect it to the power contactor.


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## woodchucker (Mar 18, 2018)

Also did you check the output for AC?  I have noticed that some transformers say DC out, but I get AC out.  Not sure why they claim DC out. They do work as intended, but it's quite odd.  its like they are missing  diode or Bridge rectifier.


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## chips&more (Mar 18, 2018)

Get “two” led halo lights and a diode. Hook them all up in series to your 24vac output. And call it a day! Good Luck…Dave

Edit: or, better yet, bridge rectifier with slightly different wiring.


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## JR49 (Mar 18, 2018)

I just used an old 12VDC output "wall wart" that I had from an old ?? (don't remember what).  I wired it to the Halo light and plugged it into an outlet.  Been working fine for years.  I suppose if you don't have any 120V outlets nearby, you could solder wires to the wall wart blades and connect  to a 120v source inside the mill electrical box.  I never throw those wall warts away.  Even all my kids know to never throw anything powered by a wall wart away, they all come to dad.   Happy Machining,  JR49


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## BFHammer (Mar 18, 2018)

jwmelvin and mksj - hit the nail on the head.  Problem solved and my electrical education continues. 

Thanks!


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## jwmelvin (Mar 18, 2018)

Glad it worked out.


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## Blackjackjacques (Mar 18, 2018)

To eliminate interpretations, it would be very useful if you could sketch up a quick schematic of what you are connecting and how you are connecting.   The converter says it can supply 12 VDC @1.5 amps - or 18 watts.  Assuming that your connections are correct -- if your LED HALO lamp requires more power than 18 watts, it could be that you are demanding more from the converter than it could supply.  Let's see a schematic sketch and identify the rating of the LED lamp.


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## mksj (Mar 18, 2018)

Halo LED lamps draw about 300mA at 12VDC, the problem was that he was seeing the voltage drop in the AC but not connecting it to the other pole or what is shown on the schematic as the 0V or return AC tap on the transformer.

Glad you got it worked out, sometimes it can get a bit confusing, I also use a LoZ multimeter to eliminate measuring phantom/induction AC voltages.


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## wyodano (Apr 30, 2018)

BFHammer said:


> I posted a version of this question prior to the server crash and thought my problem was a bad converter but I got a new converter and still have the same issue so I’m posting again.
> 
> I'm trying to install a led halo light on my PM932 mill. I picked up the AC/DC converter below from amazon and wired the 24VAC inputs one directly from the tap off the 24V side of the transformer and one from the protected side of the breaker fed from the same source. Both showed approximately 24V AC on my meter with the mill power switch off. With the mill power switch on they both read approximately 20V AC.
> 
> ...


I would un plug the ac/dc adapter and make sure there is 24 ac there then check the out put on the Freq setting of the meter ,,,,0 would be DC 120 cycles would mean yu need a small Cap. to flatten it out


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