dragon ninja pcb (problem)

[newlands1]

got dragon ninja when i plug in pic has small line at top of screen and screen is out of line.there is a slight humming sound to but not hat bad. in the picture of the board i have marked a part . do u guys think this is the problem .

http://i1126.photobucket.com/albums/l601/newlands1/DSC00104-1.jpg

http://i1126.photobucket.com/albums/l601/newlands1/DSC00103.jpg

newlands12011-06-24 12:32:23

 

[P-Man]

you have marked the sound amp... that looks normal to me..

the line in the screen and the humming noise are just artifacts of it being a bootleg pcb, i've seen it before on dragonninjas, if it bothers you, you'll have to buy a real one

enjoy

 

[Lee]

I've got a picture fault with my original dragon ninja pcb the whole screen has a blue tint to it (RGB Fault???) has anyone had this before? Any idea where to start looking??

Thanks

 

[cliff_poole]

Try cleaning the edge connector first.

Are schematics available for this PCB ?.

 

[Lee]

Tried that yes and I've found a schematic diagram. Any other ideas anyone?

 

[favouredson]

The colour signals are processed in this portion of the main board.

 

[cliff_poole]

Snip the colour output section from the circuit diagram and post it here.

 

[Lee]

Right
 
Ive traced the BRG traces to parts FB1, FB2 and FB3. 1 being red, 2 green and 3 blue.  so i thought id desolder each in turn to see what difference it would make to the screens picture, removed FB3 and the picture went noticably green, so i figured this was operating ok, then FB2 again the pic noticably changed but when i did the same to FB1 (red) the picture only changed slightly also i noticed when i reconected FB1 that everything on the screen that should be the colour red was very dark and not very red at all.
 
 
Going to change it and see if that does the job, fingers crossed
 

 

[cliff_poole]

It definately sounds like your red level is too low. Any idea what sort of component the FBs are ?. Some sort of filter maybe ?. If they are in series with the signal and the corresponding colour disappears when you remove it, you could just be removing what red signal there is and then adding it back. What happens if you swap FB1 with one of the others ?.

 

[Lee]

Well the symbol under the part says inductor but it's pure black no markings any where. How do you find out what it's values are?? Any ideas??

Thanks

 

[cliff_poole]

Is it one of those black lumps in favouredson's picture, if it is then it is probably just a wire link with a ferrite bead around it.

In fact, come to think of it, FB Ferrite Bead

, maybe ?.

If it is a wire link, just test it with a multimeter, should be a dead short.

Trace the red signal back a bit further, see where it goes.

 

[Lee]

Yes it's the one on the left. So are we thinking it's not that??

 

[cliff_poole]

Not likely if it is a wire link. Test it with a multimeter compared to the others to make sure.

 

[Lee]

Well I've swapped it with green and the red and blue now work so I think it is that.