Japanese SFC not displaying the corrects colours

Just powered on my Japanese SFC after not using it for a few months and the colours are showing off and mixed up. There isn't any corruption with the sprites as such, it's just all the colours are just wrong. The games play find and the sound is also correct, but the colours are just wrong.

I've tested the RGB Scart lead and power supply with my USA SNES and they are both working correctly.

So it's an issue with the SFC unit directly

Having done a search on the net, the reply by Gargantua Blargg in this thread, sounds like it might be the same issue:
https://www.ifixit.com/Answers/View/26981/Why+do+my+games+only+play+in+black+and+white

Reply is as follows:
I just fixed my SNES with this problem, monochrome output on composite and S-video. Occasionally some color would appear. It was due to the master clock crystal frequency drifting slightly with age. To fix, use gamebit driver to open SNES case, remove just screws holding metal shield over circuit board (leave power switch in place, as you don't want it shorting with board), then reconnect SNES to TV and put game in, power on, observe monochrome output, then slightly adjust the small screw in the red component near the front. Mine had to be turned slightly counter-clockwise, but try both directions. Once you find a position that works, turn it more to find where it stops working, then turn it back so that it's not right at the edge of working. This fixed the color on mine and now it works fine.

Also see the answer below about replacing the crystal in case just turning the screw isn't enough. Anyone else had the same issue or knows how to fix it directly?

Thanks

 

Update, right seems this issue is more troublesome than I hope. It appears the colour blue and bright whites aren't displaying mainly. So this would suggest a video between the decoder and/or RPG output. One or two effects show up correctly but most don't.

It's a 1990 model Super Famicom with the plug in sound card, anyone have experience of troubling shooting a problem. I've fully clean and tested the SFC today, couldn't see any signs of damage to the trace. Tried adjusting the pot as mention above, but that doesn't affect RGB, only S-video and composite output.

Guys at the YT channel I work with did a video to help out, it's certainly an odd one, caps and stuff all look good. Think we will take the whole thing apart this coming weekend and put it under a fine-tooth comb, checking and testing both trace and solder.



Dare I say it, but is this a sign of a fault with one of the chips, assuming it isn't dry solder on a pin or something.

 

Looks like PPU2 is bad.

 

Consider a cap replacement. Bad caps don't always look bad. If u still get distorted colours then it definitely could be an IC issue.

 

All likely issues are within an IC that needs replacing.

 

I agree with Ergot_Cholera on the PPU2.

Also here's a great site,has a bunch of useful info.
http://projectvb.com/nss/logs.htm

 

Cheers for the feedback, seems like you all think one of the chips has failed is this a common problem on early model Super Famicom? Seems this PPU2 unit failed after 28 years. Does anyone in the UK sell those SNES Burn-In Test Carts, mentioned in the link Pikkon posted.

Looking at the board again one or two of the solder point did have a slight brown look to them, none near any of the CPUs, if I get the time I'll grab a few pictures of the board and PPU2.