I bought a DC jack already connected to a wire set. It exactly fits the 12 volt out in my presenter. It has a black and white wire and a black one. I soldered the black and white to the red and the black to the black, switched the presenter down and the screen did not lower. So I reversed the soldering scheme and still no go. The electricians who wired my room ran 16 guage wire over some thirty feet of drop ceiling. Is it possible that the the scale of the jump between like(I am guessing here) 28 gauge to the bigger wire and , considering the length of the run, means that the 12 volt signal just gets attenuated over the distance.
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Do you have an ammeter you can use to see if it is drawing any current? For some reason I don't think the gauge of wire is the problem, if you really have 28 awg that might be a problem, but that is really small I doubt it is 28. My guess is that the power supply cannot provide adequate power for the motor.
Hehe I was guessing when I said 28. I knew that higher number meant smaller and lower bigger. Also I must have been tired because now that I have looked at it again. The bigger wire, while bigger is really that much bigger, I mean duh, I soldered it. I just somehow jumped into lala land when I was pissed it wasn't working. So when I got home what was sticking in my pee brain was the overall size of the feed casing. It had three wires in it. a black a red and a white. The electrician left me a red and a black which I assume is right. I know the volt ouput is 12 v but I will have to find out the amp/s or ma/s.... k found it, 200 ma. I do have a anameter which I brought with me yesterday so I will test today(forgot battery) as far checking I know I was going to test the end of the dc plug for 12 volts(and now200 ma) I wasn't sure, however, how to test it at the receptacle end. I know that the barrel wll have either a +polarity and the inside a neg polarity. Since there isn't much power here if I touch one end to the outside of the barrel and the other down its throat, will that give me an accurate feed? Anyway now that we know it is only 200 ma know that I should not need larger gauge wire, correct? Forgive me for not starting this out on a better foot but I was tired and frustrated and wanted to blame it on something. I will get back after school tomorrow with what I have found.
200mA is fine over 20-24AWG...you could run it on phone line or Cat5 cable if you were in a pinch.
Test the end of the transmission wire first...make sure you've got volts and amps.
If you've soldered it together, peel back your tape/insulation and test _before_ the solder.
If all's well, test the plug. If you've got nothing, cut off the plug end and test.
If there is no polarity marking, just test for continuity by switching your ammeter to Ohms.
With pigtails loose (not soldered to anything), attach one lead to the pigtail. Probe with the other to see if that tail is the inside or outside of the plug. Verify continuity on the other tail as well.
No.....don't cut off the plug! If you want to check your transmission wire separate from your plug, you'll have to undo the soldering or cut the wire.
I suggest you cut about 1/4" into the transmission wire side (free), so you aren't cutting the tail end of your plug (paid).
don't cut the plug!
well, nothing other than miliamps at the newly cut/desoldered ends.
aarg!!! No continuity at all. Crap, I first tried a cheap tiny little radio shack solder on jack and got just enough if a cross to make the thing tyr to go uo and down at the same time. The signal conflict has nuked ny dc out. My only hope now is is if a 5100 mp has an accessible fuse, double aaargh.
For the power line, you should only be measuring amps. Continuity does not exist.
Continuity test is for the plug (not connected to power line):
Switch meter to Ohms.
Put one probe on the black tail.
Use other probe to touch outer and inner.
When resistance is gone (needle goes up, or digital reading is not zero), you've found that wire.
Repeat on other wire.
You should be able to see continuity for both tails.
Hope this helps.
k I hope you all are still monitoring. I have dismounted the projector and am ready to test the amp output. The problem is that the barrel and the cylinder are so close together that I have a hard time making contact separately without crossing them. if I twist some thin but stiff wire around the end of each probe so that I can touch both surfaces without touching each other , will my read still be accurate and doI need to get my wire in contact with the inside of the cylinder or will simply touching it to the exposed surface be sufficient?
I've used small paper clips or finishing nails in the past. Twist around probe and fasten with electrical tape if is slips too much.
Push the probe into the barrel until it contacts the metal inside. Imagine the shape of the pin that normally goes in there...you should insert probe that far.
Now, my new meter has probes that can be changed. So I bought a pair of probes that are sharp as a needle. They come with rubber caps so you don't stab yourself (often).
One probe on outside of barrel.
One probe inside barrel.
I stole picture from here. Also good explanation of AC/DC converters.
http://support.radioshack.
tip
Whew! You have set me on the right path. When I went deep with red and tipped black I pulled .oo2-.03 When I ran the continuity test I found that my tip was positive and the barrel negative. So now I just need a source for a plug with the exact same specs except tip + and barrel -. Thank the electrical gods (and you)
Just a note for clarification. You have three polarity orientations to check:
1. power supply
2. plug end (tip and barrel)
3. load (the motor or device)
In your case, the power supply is separate from the plug end. If your device requires tip positive and your current plug end is reading tip negative, all you have to do is switch the tails coming off the tip.
So if black->black and red->white is giving you the wrong polarity, just switch your soldering to be black->white and red->black. Simple.
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by: aleghartPosted on 2008-04-08 at 18:41:51ID: 21311235
I think you had it right: black to black, stripe to red.
How many mA current are you trying to run? We run much farther distances of 12V and 24V DC over wires smaller than 16AWG, but it was 200-300mA (over 200')
What is "28 gauge"? The wires leading to the DC plug end? I've never seen anything that small. I've seen 24AWG. It wouldn't carry anything more than ~500 mA. 28AWG would be around 200mA.
So, if you screen motor needs 500mA or 1A or more, you need larger gauge wire.
1. check the amp output of the power supply
2. if safe (i.e. not a car battery) check voltage and amps at the open end of the 16ga wires
3. diconnect power
4. splice plug
5. reconnect power
6. check voltage and amps at the plug
Also, check on or inside the chassis for a popped circuit breaker or blown fuse.