SNES schematics SNSP-CPU-02

Hi Guys

I've got a snes i bought off eBay as a fixer upper.
Apparently it was an untested loft find. however after opening it up and realising that some screws were in the wrong place (including 1 of the gamebit screws holding the rf shield in place)

I found that the pico fuse had blown and one of the caps had been replaced but only had one leg actually soldered to the board.

I've replaced the fuse and reattached the floating cap and done the usual cleaning the cart slot & the oxidisation residue from between the chip legs but still getting a black screen. The rest of the caps don't look like they are leaking and i cant see any obvious corrosion or damage to the traces apart from one crack in the pins for the expansion slot, so I thought a sensible place to start was to check the power rails.

Searching google for schematics so far had pulled up low res drawings on google images and logn abandoned forum posts of people trying to compile board diagrams.

Can anyone point me in the direction of schematics for this board or even a list of which pins are power and ground on the main chips?

Thanks
Grant

 

Hey Grant,

You may want to check out this thread on nesdev - http://forums.nesdev.com/viewtopic.php?f=12&t=10470 There is a hyperlink provided by the OP that points to some schematics he created after some of the rather bad scans that were out there already. jwdonal's high resolution schematics should really help you out if you are in need of easy to read SNES schematics. Obviously, there are different revisions, but his schematics are quite helpful.

Note that there are a few mistakes on there that are mentioned in the thread.

Are you getting a black screen AND no sound? Early units sometimes have the CPU fail. Note also how the reset line works on the system - If, for instance, you have a bad reset connection to the audio, the system will hang on boot.

I am hoping you either just have a rough trace that needs some TLC or even simply corrosion on the AV connector itself. I also assume since you are asking for schematics and talking about power and ground to the ICs that you are already certain you are getting your +5v from the 7805.

 

Thanks I will check out those links

There is no sound or video when the system is powered up,
I will admit that given the stater of the board i didn't think to check the voltage regulator. I have checked it now and am getting +6.6v between the output leg and the pico fuse

Although when I went to get the console to test it i found that my wife had dumped a t-shirt on top of the board :S

 

I have a snes mini that would display a black screen and the snes read at around 7v so I replaced the 7805 and it worked.

If you want to just see if it works you can hook up usb cable to a 5v point,the output on the 7805 works,ground can go to any ground on the board and plug it in to a usb source,pc always works best for me as a usb psu usually doesn't work.

 

Ok so checked again between the output and ground pins on the 7805 and its 5.0v
Ill get to reading over the next few days

 

hi ! any news ? i have the same problem on twice snes with cpu-01 and cpu-02 motherboard.

they also have au sticker "c59" on the bottom.
this sticker is about a repair in factory of the C59 capacitor...

i have changed capacitors and regulator by a dc-dc converter with high capacitor for filtering without success, and one of these snes worked great 3 month ago...

it's appears this problem is not only for a signle revision of pcb.