How to test diode - ViewSonic N3250W Television

If it's not shorted and doesn't have a burn or chunk blown out, it's probably good.

Diode test info here:
http://www.microtechfactoryservice.com/diode.html

Here's the battery-assisted test you're referring to (6V is okay):

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is this a question,?
1: is mine bad, how to test it or find it, in the global sense?
2: where to buy one.
3: which brands are best.
4: how to do a basic diode test , front to back ratio testing.
5: what are the symptoms of a bad diode.

ill throw the ice 2+3 = 5.
the Modern ALT has many diodes. (and more{in dah reg})
the 2 main, sets are , the 3 phase set.
and the keep alive pack.
ill not cover the keep alive pack or the regulator diodes..
the 3 phase pack take the 3 AC phases and converts them to Pulsating DC. (in effect simulating a DC generator)
if 1 diode opens , you lose, 1/3 of the total power.
so 50 amp alt is now a 33 amp alt. (weak as a cat)

if the diode shorts, it becomes this huge noise generator.
(turn on the AM radio , here it sing and raise pitch as you gun the throttle (i use a scope to see bad diodes) bingo.
the noise can in fact cause any electronics on the car to go nuts.

the diodes also have one other feature, ill skip here, (zener actions)

To test a diode, use an ohm meter. Place the red lead from the ohm meter to the anode, "Positive" end of the diode, and the negative lead to the cathode,"Negative" end of the diode. If it is good, you will have some sort of a reading. Then switch the leads around. If the diode has no reading when the leads are switched around, the diode is good. Remember that at least one end of the diode has to be desoldered from the circuit board.

HI:
The problem is a open high voltage diode on the high voltage capacitor, this link will help you in repairing or testing the diode yourself, CAUTION!! The high voltage capacitor must be discharged before attempting any repairs or testing, discharge by shorting the posisitive terminal to ground. the diode is attached to one of the terminals of the capacitor and the other end to ground.
http://www.partselect.com/microwave+test-diode+repair.htm

I'd say your diode is bad but your capacitor may be good. You need to test it further - as described below.

In order to get reliable measurements to make a determination about the condition of the components, each should have at least one lead removed from the circuit. If not, your meter will read the through the rest of the circuit - and not be limited to the diode or capacitor under test.

To check a diode: Set the meter to to the lowest scale (Rx1) and touch black (-) probe to the cathode of the diode (the end with a band around the diode body) and the red (+) to the anode lead to reverse bias the diode. The meter should indicate "OL" or high resistance. Reverse the meter probes so that RED (+) is on the cathode lead and black (-) is on the anode to forward bias the diode. The meter should read a very low resistance - approaching 0 ohms. Diodes should conduct in one direction only - and the other is should look "open" If it conducts or is open in both directions, it is defective. Zener diodes can be checked with an ohm meter, but need a variable voltage supply and are required to be in a circuit (instead of out of circuit like a standard diode) for accurate testing. A link to zener diode testing here.

To check a capacitor: Set the meter to the lowest scale (Rx1) and touch probes to capacitor leads. The meter should indicate "OL" or high resistance and show steadily decreasing resistance before increasing to OL or high resistance again. Swap probes from the meter on the capacitor leads and "OL or high resistance indication should change to an even lower amount of resistance thas before before returning to "OL" or high resistance indication. These are test result characteristics of a good capacitor under test.

I hope this helps & good luck! Please rate my reply - thanks!

THRE ARE MANY POSIBILITIES.HERE THEY ARE:
1. Check your charger's wire.Most of the wire s are always damage in the root of plug & to the opposite side.
2.Check the fuse.
3.Check the Rectifier Diodes.How many Diodes do your charger has?most of the chargers are only one,sometimes 4(a bridge type,& somtimes only one but 4 legs( it is also called a bridge type)
to test a 2 legs diode is just simply get a multi tester and adjust or set it in X1.,then look for the white band(mark) of diode,if you can see that mark,remember that it is the positive side.what will you do is put the red pin of the tester to the positve side of the diode,& the black pin of the tester to the negative side of the diode.If if the neddle of the diode will move,then you must reverse the pin of the tester,the red pin now will be put in the negative side of the diode and the black pin of the tester now will be put on the positive side( to the side with white mark or band).
now,if the neddle of the tester WILL MOVE after doing this reverse test: im sure that your diode is dead and needs to be replaced

Note:even most of the time you can do testing diodes attached on the board..,it is strongly recomended to detach one leg of the diode to the PCB or circuit befor doing the test.

you cannot check a microwave diode with just a mutli meter . you have to make a test jig take a 9 volt battery and a meter with dc volt scale set up the meter just like you would test a 9v battery .with me so far ? now remove one lead from the battery and insert the diode between the battery and the test lead .......take a reading . now reverse the diode take a reading ........ i just tested a diode before writeing this and this is what i got my battey volts where 9.2 v whith the diode inserted i got 7volts . reversing it i got .02 volts dc . a diode is a one way valve and mine is good because it passed curent only one way ...yours should be about the same ....... if you understand this please leave me 4 stars ! i even went out in the shop and tested a diode for you just to make sure my answer was correct

To test a diode, first remove it, then use a test meter with a diode check facility. Test component first one way around, then the other. It should give a 1 in one position, and 0 in the other if all is ok.

This is the correct way to test a diode.

using an ohmmeter' the B to C junction will test as a diode, but E to B junction will show low resistance, approximately 50 ohms in both directions. now, E to C ohmmeter test will test as a diode. the foregoing results indicate a good transistor. reading other than this indicate a bad H-output transistor. good luck!