SNES Mainboard Repair Corrosion [Serial: UP15971140]

Just thought I'd make a thread to track my repair progress for some SNES units I came across recently. This one has the serial of UP15971140. Currently it shows a purplish screen and the composite signal is detected as SECAM instead of PAL.
Pulled it apart and found some corrosion around the area of pin 25 of the S-DSP pins.
I'll give the board a clean as best I can and retest. The corrosion appears to have entered through the cartridge slot. There's not really any capacitors in that area, although there certainly has been some leaking at the back end of the unit as the board is quite greasy.
Here's hoping we can get something more out of it than just a blank purple stare! :loyal:

 

Tried it out on RF since composite couldn't seem to keep a stable lock on the signal at all and err... vertically flipped text... is that a bad thing?

 

This is the area of interest for the repair:



By the look of it a few traces got corroded there.

 

Thanks! You are spot on, we've got corrosion alright, might be repairable.
Did the caps on it this afternoon and noticed the corrosion, that'll teach me to not check my inbox more often! :biggrin-new:
It was interesting to note though that some of the caps had definitely leaked out and left gunk on the board.
People need to start recapping their precious SNES decks sooner rather than later!

 

Are leaking caps inevitable or is it due to storage conditions?

 

I'd be inclined to say inevitable, but I have no idea how these were stored up until now.
Just a matter of time before the chemicals eat away at everything around them!
Like a rabbit in a lettuce field!

 

Well apparently in the snes leaking caps will never happen, as I got lol'ed at by a member of these forums not to long ago. Shame i fixed a snes by replacing the caps....

Might of been in denial could of been a nintendo fan boy, but sorry to say 90's caps are 90's caps (ie known bad run).

 

Ahhhh don't let them get you down!
They are getting on in age anyway, all those corrosive chemicals sitting inside such a tiny space.
They simply want to be free, corroding you and me!
I'm about to have a go at fixing up and checking what traces are dead on this one now that the no sound one has a cause identified! :topsy_turvy:

 

Am not to worried for myself, it is for other people who are looking for a fix and when they read "it could happen....in an alternate universe" could put doubt in their mind.

For myself I know what I have seen and done so as the remark towards me...meh.

 

Oh I see, but that's where the hired goons are separated from those with a passion for never giving up on replacing capacitors.
Hell, if new capacitors can bring a Sophia back to life, anything is possible as far as I am concerned! :biggrin-new:
Uh oh... that reminds me I need to recap my VA0 Saturns sometime very soon!

 

Electrolytic capacitors all have a shelf life, it doesn't matter if they were originally made in the 90's or whenever, they will fail at some point.

 

Hope you get them fixed!

 

Thank you for clearing that up........

 

If they don't leak they dry up and then don't function anymore. I had them dry up in my NES and suddenly the sound was ridiculously low. Quick recap later and all was well.

 

Not sure why the dots, but hes right.

 

Progress has been made! Discovered three traces were not connected. Thankfully vias were present!
PPU1 pins 34 and 35 were not connected and neither was another random one, seemed to control video signal.
Without the random trace joined video was very unstable over composite and would drop out. RF was stable, but fuzzy.

1. Initial state, all three traces broken.
Symptoms: Text scrambled / inverted and video drops out intermittently, sound is perfect.



2. One trace repaired, two damaged.
Symptoms: Text scrambled / inverted and video now solid, sound is perfect.



3. Two traces repaired, one still damaged.
Symptoms: Text scrambled to a lesser extent / still inverted. Video still solid, sound is perfect.



4. All three damaged traces joined up.
Symptoms: It's still an EA sports game... :biggrin-new:

 

Well done mate! Top work.

 

Thanks! Glad I got there! Here's some photos of the repair work.
I really don't like small vias much... but managed to get enough solder to stick thankfully, some filled with solder quite easily.
Full photo gallery of this unit here as usual!









Video to come of course as I solder them one by one! :encouragement:

 

Vias - scrape them as they are usually covered to protect the copper. Put the wire through the hole, then solder from the other side. Easy

 

Have you seen the underside of a SNES board? There's more lacquer than the back of a Saturn CD deck! :topsy_turvy:

Edit: Wait! I see what you mean, use a good length of wire to feed the solder through from the underside! Genius!
I'll give it a go when I'm replacing that 2.2F capacitor in the near future! Thanks!