Lt456s/polarity\ power supply pin polarity

If you are sure that you've fastened the RG59 properly, most probably you had your power supply pins on incorrect positions. Just try to interchange the polarity of your power supply that is connected to your camera. Most analog camera's need the right polarity. "Positive to Positive" and so goes for the "Negatives".

You need to find out first the PIN assignments (you have 4 pins) from the diagram of your unit. Try find a manual from the system manufacturer website. This way we can be able to understand which is the +/- (polarity) and requires the 20V input. Maybe you only need to tap from 2 wires in it, then the remaining wires can be just a signal or voltage sensing.

A variable power supply might be able to help and you can find it in Radioshack or similar electronic or DIY stores. These types of power supply only has "2-pins" however, but will allow you to select voltage and polarity for your needs.

Center pin is POSITIVE (+)

Many USB power supplies will have the right plug. I picked one up by buying a cheap USB hub, What you want to look for (most likely on the bottom of the power supply) is VOLTAGE Output: 5.0 VDC, POWER Output: 1.0 amp or (1000ma) and the center hole is the positive side. I have even seen some BluTooth earpiece charges that supply what you need.

Hope that this will help.
AAirwolf

Well, you might try:

http://www.yub.com/products/?productID=3190411

The supply has a three pin connector and supplies +10 and -10 volts at unknown current. Don't have a pinout.

I am sure you can cobble something up if you can''t find the ACH120 official power supply.

You would need to find the pinout polarity to connect power if you have to make your own. One would taake unit apart and trace those input wires to something that would define the polarity. First find ground, then look for input filter caps which will tell you the polarity on the pins.

I just connected a new power supply to my zip 250MB, with the center pin as positive - and it worked out well :-)

Is 12VDC 2,0A the inner pin is + and the outer pin is -

The correct one would be 12v @ 2.5 to 3 Amp.
If the set used less current than 1 amp it would be in milliamp (500ma which is half an Amp)etc.

As long as you get one that is 12v @ 2.5 to 3 amp it will be fine.
You could buy one with a higher current rating like 4,5,6 or more Amp's as long as it's 12v DC. The set will only use the current that it needs to function so I higher current won't hurt. It's the voltage you have to make sure is correct. If you do buy one with a higher current rating it will probably last longer because it wont get so hot.

Problem is just external...First try in another pc,if it still wont work so just buy new external and put that hdd in new external...

If you ask them nicely they just might tell you, else it's only $5 for a user manual(sorry no luck online); http://www.maginnovision.com/service.htm this link has a picture that maybe shows a power cable going to the bottom right (as you look at it) but it's hard to be sure; http://www.amazon.com/gp/product/customer-images/B0002CF06K/ref=cm_ciu_pdp_images_all/104-1966292-9407907?ie=UTF8&s=electronics#gallery this link shows what the power lead should be like - look for a hole that matches; http://cgi.ebay.ca/AC-power-adapter-for-MAG-innovision-lt456s-14-LCD_W0QQitemZ8824271526QQcategoryZ3698QQssPageNameZWDVWQQrdZ1QQcmdZViewItem Hope this helps, if not ask again :)