Completlly stop working after wrong polarity lead been plugged In
Hi accidentally used a wrong polarity lead from a 7.6 v DC power supply plugged in to nv-ds60, after that no more response, pulled the circuit board out under the battery, trying to find a fuse or protraction circuit, find a component call FL1201 but still got a circuit through. is there any other fuse or protraction device? what damage it down when the supply is wrong polarity? Any one can help me? how to solve the problem?
Re: completlly stop working after wrong polarity lead...
One of the first things that go are is the protection diode coming off the + input. Then a fuse and so on. Surface mount fuses are light in color (usially green with white text). Attempt to bypass these components with a small wire or paperclip. Once you follow the lead from positive input you will run into a black rectangular block about the size of a grain of rice with 3 leads. That will be your voltage regulator. Its set at the correct voltage, and since you already have a power supply with a set voltage, then you dont need it. Its also the first thing that blows when you switch polaritys. (voltage regulators have 3 pins - input output and ground) when you switch polaritys that ground becomes the "input" and ..... go to all http://www.alldatasheet.com/ and type in the text you see on that component. It will then identify the component and list its voltage output and at which pin. Apply set voltage to lead and ... pray?
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You need to figure out how the interference is getting inside.
Look at the external connections.
HDMI Cable or Perhaps the Power Connector.
Noise from the power cable would be most likely.
A Ferrite Bead can often be clipped onto power lead to dampen electrical noise. Electronics supply stores have these.
If an AC to DC external box is used. What is the required DC input to your DVD ?
For example if the AC is dropped to 12v DC and then plugged into player via a small connector. You could get your own connector and supply from a 12v vehicle battery. Be careful to maintain correct polarity to tip of connector.
Use a cheap multimeter to check voltage & polarity.
Substitution....This would prove that the noise source is from the Power Supply.
Check the polarity of the adapter, if it isn't the original one. Even if you have the right voltage, it still has to have the mA or higher but, most important is the polarity. Most guitar pedals are wired backward on the plug. The positive is on the outside ring of the plug and negative is in the middle. There should be a picture or diagram somewhere on the unit close to the plug to find out. If it is backwards, it could have damaged it, maybe not though. If it is ok, cut the plug off and switch the wires and check it. After all, it's not working now, it couldn't hurt.
Not only do you need the correct voltage and amperage (MAH) but you need the corectly sized plug to fit the socket AND it has to be in the correct polarity. Usually the polarity is marked by a broken circle with a dot in the middle. Leading to this dot will be an arrow or just a line and at the other end of the line will be either A positive (+) or negative(-) It's important you get this polarity correct when plugging a new power supply in.
Your local electrical store should be able to sell you either a fixed 12volt supply or even a variable supply allowing 3, 6, 9 or 13 volts output. Make sure it has the amperage capacity you need. It won't matter if you need 500Mah and the supply is 750Mah as long as it isn't less than what you need.
The power supply should come with an assortment of plugs which are insrted into the socket on the end of the power supplies lead. Follow the instructions on the packaging and ensure you have the center pin set as either + or -. If you are in doubt. Take your speaker which has the socket fitted and show the salesman. He should be able to pick the correct plug and make sure it's the right way around.
If you plug it in and nothing lights up, quickly remove the plug and turn it 180 degrees in the power lead socket. Obviously it's been put in the wrong way round. If you were quick enough no damage should have occured and away you go.
Just one tip. Wrap a small piece of insulation tape around the plug to stop it from being pulled out of the power lead's socket. They do tend to work loose after a while. Oh and make sure it's switched to 12 volts if you get the variable one.
Most TVs today use a "hot-chassis" design and a switch-mode power supply. You should use an isolation transformer when doing any service work on a TV. This helps protect you and your test equipment, and can prevent accidental damage to the TV by grounding parts to the wrong point.
Hot-chassis sets use two different grounds. The power supplies have one ground reference for the primary side (hot ground) and a different point for the secondary (cold ground). The point you pick will depend on what part of the TV you're measuring.
If you are troubleshooting a dead set and working on the primary side of the power supply, use the negative lead of the large electrolytic capacitor you'll find near the AC input connection. There's almost always a bridge rectifier and filter cap (300 to 400 uF range, 180 to 250 volt rating, so physically pretty large) in that area to make the raw DC. That's a guaranteed good hot ground. Sometimes the set will have a labeled hot ground point right on the circuit board for you.
For measurements on the secondary (output) side of the supply, almost any shield can is ground. The tuner cover is a good choice.
Normally, the polarity is molded next to the connecter hole; it may not be real easy to see.
If you have a digital multimeter with a 'diode' position, most devices have a diode internally installed to prevent damage in case of a bad substitution and the meter will show a value of somewhere between 500-800, typical would be in the mid-600s.
If you find that, then the meter is currently causing the internal protective diode to conduct as it would if the WRONG polarity would be applied and most meters will supply a positive voltage to the red lead for diode function.
Commonly, the center is the positive contact but this sure isn't certain.
So the old power supply doesn't have the output voltage, current and polarity noted on the label? What a ripoff! *grin*
Did you look on the case near where it plugs into the monitor? Sometimes that will tell you the voltasge and polarity.
Poliarity? Get that one wrong and the monitor could be cooked instantly! But it's usually positive.
I found a completed eBay listing that had this info:
"the power supply which the seller used to power up this Planar Flat Panel is inventoried as follows: ViewSonic 12V Power Adaptor Model # SYS1126-5012"
I looked that one up, and it's listed as 12V at 4.17A. PC Hub has them for $28.62: