Transistor Testing

[bobbyskillz]

I have an NPN Transistor (c1815gr) that I'm testing on a power board from a Gateway monitor that has 2-seconds to black.

I get continuity both ways between the emitter and the collector when I use my multimeter on the diode test. After a few seconds the continuity stops and the meter goes to "0L". Does this mean the transistor is bad?

I don't see any visible defects anywhere on the board. The MOSFETs I checked appear to be good.

Edit: I tested the transistor with a Fluke 87 multimeter with the transistor still soldered into the board. The board was disconnected and powered down.

[Joun]

Re: Transistor Testing

There is probably a capacitor in parallel with the pins you are testing.When it reaches fully charge it shows 0L.The only way to be sure about your testing is desolder the transistor and then measure it..

[retiredcaps]

Re: Transistor Testing

I have an NPN Transistor (c1815gr) that I'm testing on a power board from a Gateway monitor that has 2-seconds to black.

2 seconds to black can be

a) bad caps
b) bad ccfls
c) bad ccfl wiring (especially the return wiring)
d) bad secondary windings on the inverter transformer

More details starting with post #19 at

https://www.badcaps.net/forum/showthread.php?t=10419

Also, see budm's Inverter tester using old CFL

https://www.badcaps.net/forum/showthread.php?t=19987

I get continuity both ways between the emitter and the collector when I use my multimeter on the diode test. After a few seconds the continuity stops and the meter goes to "0L". Does this mean the transistor is bad?

Edit: I tested the transistor with a Fluke 87 multimeter with the transistor still soldered into the board.

Nice multimeter. When testing in circuit, other components could be affecting the measurement.

I would check out the other things as written above.

[bobbyskillz]

Re: Transistor Testing

Thanks for the quick replies!

I printed the 2-Seconds to Black instructions and have them as a guide. I'll desolder the transistor and see how it reads. I also plan on assembling a test CFL. I'll be sure to post back what I find!

[bobbyskillz]

Re: Transistor Testing

The transistor seemed to test okay. I just have to pull apart a CFL and test it. If that doesn't work, I'll go back to component testing.