Super Famicom black and white problem

The picture is fine,every game plays great but the picture is black and white,sometimes I will see a shimmer of color for a second on booting a game but it returns to B and W.

I replaced all of the caps expect for the power cap,changed the crystal and the trimmer cap and still nothing.
I might replace the video encoder but still want some input and what's causing the problem.

 

you didn't change the large cap under the heat sink? i've had that cause video problems all by itself. you should swap that out.

 

TV support ntsc?

Sounds like a composite connection to a TV that doesn't support ntsc well/at all. Try rgb if you have not already (and if you think you are using rgb, what leads are you using as could be a resistor missing in the cable)

 

My tv does both ntsc and pal but the tv is not the problem and I can't try rgb but can try component and the model of the super famicom is shvc-cpu-01.
I tried rf,composite and s-video but still a no go.

And skyway1985 I can change the power cap,didn't think that could cause video problems.

Thanks for your helps guys

 

It really does sound like a NTSC incompatibility problem. Especially the flicker of colour when you turn the console on. That's usually a dead giveaway. Can you at least try it on a different tv? What model tv is it?

 

The flicker of color only happens rarely but I just tried the super fami on my sony crt and still black and white.

 

pikkon, you're in the US right? seems very unlikely its a tv standard issue.

 

I had op confused with someone in Australia.

Does the console have any mods to the video output?

 

There's a trimmer capacitor near the clock crystal. Mark the position it's at and then try turning it / see if it restores color.

 

I'm in the US so no tv issues and the consoles has no mods to the output video.

The original trimmer cap did nothing when I adjusted it so I swapped it and when turning the screw it would freeze the game but nothing on restoring the color.

 

I have had a few sfc that display in b&w at 60hz. For all the cases i have seen its due to the crystal. One case the trace leading to c4 on the underside was broken.

Seeing as though the xtal has been replaced, check the traces.

 

I checked C4 and there's no broken traces.
I have another working board so I've been using that to find any faults with the broken one.

Thing is I have fixed 2 other snes with this problem,first one was a bad trim cap,second was a broken trace under the motherboard.

Edit

I just swapped out the video encoder and it's still black and white

 

Perhaps a trace leading to the video encoder is broken?

Is the board in good con?

 

I have used this to colour correct 50hz composite video for sfc. If all else fails perhaps this will help?

 

Thanks for the picture but I may have found the problem,you guys think X2 can cause a black and white picture.


I do have broken board I can swap it out with.

 

Not sure about x2.

Have you tried solder reflow on the ppu's? In particular ppu 2, pretty sure pin 3 on ppu2 provides the 3.5xx mhz for colour on ntsc snes.

Or perhaps try pressing down on the chips?

 

X2 provides the clock for the APU. Nothing to do with any of the video.

 

Your right,don't know why I didn't look at the schematic.

But I did the component mod and I do have color but still can't figure out the problem.

 

X2 is a 4Mhz clock source for the CIC chip. It has nothing to do with colors. Neither it has anything to do with the APU. APU runs with a 24Mhz ceramic resonator (blue thing near S-SMP and S-DSP chips.

 

Whops, it's been a while ;p