G07 vertical deflection problem

ArcadeGreg

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Hey guys,
I am working on a electro home G07-CBO, and it has vertical collapse. When I found the chassis it had a blown fuse (F901). I replaced the fuse, and tested the HOT. It was bad too, so I replaced it. I am now about to test the vertical output transistors X401 & X402 (I tested the fusible resistor FR401 & it tested good at 68 ohms), however I am not sure how to test the VOT's. Do I need to remove them from the board? Can I test them from the solder side? Set multi-meter to diode setting? Test them in circuit while energized? Please fill me in...
Thanks again,
Greg
 
Thanks guys y'all were a big help on this one...

It was the X402 transistor. It was shorted between the collector and emitter. In case anyone reads this post, to test the transistor you should remove it from the board. If it is still glued to the heat sink, you should de-solder the 3 legs of the transistor first, then use a razor blade or exacto to scrap away as much of the glue as possible to seperate the transistor from the heat sink. If it does not separate via razor, then with a small flathead screwdriver gently nudge and wiggle on each side of the transistor until it seperates from the heat sink. You obviously must remove the screw that holds the transistor to the heat sink as well.

Once the transistor is removed from the board, and using a digital multi-meter set to test diodes, place the positive (red) lead of you meter on the "base" leg of the transistor and the negative (black) lead of your meter on the "collector" leg. It should read .5 VDC (or very close to .5 VDC). Now, leave the red lead on the base leg and place the black lead on the "emitter" leg. It should, also, read .5 VDC. If is does not read .5 VDC; for example: if it reads 0 VDC, or if it reads OL, then the transistor is bad. Lastly, you need to test the reading between the collector and emitter legs. Place the red lead on collector and the black lead on emitter. The reading should be OL. Now reverse the leads (red on emitter and black on collector), and the reading should be the same (OL). If there is a voltage reading between either of those two legs (C & E), then the transistor is bad.

Below is a video (not mine) that will visually demonstrate the aforementioned transistor testing process.

 
Your youtube link isn't showing up...try this:


(you only want the actual video ID, which is 8VK_4gZU__I in between the youtube tags)
 
Can you explain where should I put the positive and negative leads on and what should be the reading
This is x401 from a G07 with Vertical collapse
 
look up how to test NPN transistors. it's really not a complicated process, there's far worse maintenance tasks with video games. if that's above you then you're going to have difficulties with this as a hobby. you would probably have an easier time testing it in circuit.
 
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