how to tell if a ballast has failed?

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odiggity

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Joined 2007
#1
I have a dlp tv and I thought the bulb had failed. I replaced it, but it still does not produce a picture. It turns on, and blinks 10x, then resets itself. After the reset, the power goes on and I hear sound but no picture.

here are some pics:
http://picasaweb.google.com/odiggity/Tv

I took the case off and measured some of the voltages. When you close the lamp door, I read 400v on the ballast input. I'm, assuming that the ballast steps that up, but I'm not sure how high or how to measure it.

Also the lamp assembly on the right side has several fans, all of which are not working.
 
#3
On that picasa website you can zoom in with the magnifying glass on the top right of the picture. Here is a closeup.
 

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#6
i measured the voltages again. i get 377 on the left side input and 0.4 on the output.

I see that there are some low voltage lines that lead to the left side of the unit, one is labeled power supply. I disconnected that one and I get the same symptoms.

So i wonder if there is something wrong on that end, where the logic isn't tiurning on the output voltage somehow?
 
#7
ywh said:
like this?
Click to expand...


yes, i think that I am not getting that signal to turn it on. I disconnected the connector labeled power supply and found that it behaves the same. see the pic i attached

i get 3v between the black and orange lines, but nothing on the white green or red.

I measured the voltages on the power supply connector and find that i get 3v on some of the lines.

so now I think that the lamp and ballast might be fine, but there is something that is preventing it from turning on. I see that there are fans and color wheel supply lines that are connected here as well. nothing is working though. The wheel does not spin, the fans don't go on...
 

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#10
you can contact A/B/C with a screwdriver, this is means short circuit, I think that is C.
when other power is OK, contact C or B or A, the lamp will work if ballast is OK.if can not work you will to get a new ballast.
 

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