SNES - Black screen with all games

I have a Super NES that I bought and the thing won't read any cartridges, RF and A/V both just give a solid black screen output and hitting reset makes it flicker for a split second.

I have checked the following:
1. The game/power cable/A/V cable/controller/controller ports I'm trying are working in another unit.
2. Cart connector continuity - I have traced from a cart pins in the connector all the way back to the traces on the board, all have continuity.
3. There were some "rusted" traces near the RF unit which I scraped back carefully and repaired with kynar wire - I suspect the caps there should all be untrusted, but they appear to report good voltage readings.
4. The 7805 is properly working with a solid 5v coming out and the ppu/ppu2 chips seem to warm up a little after a bit of use.

Any suggestions? my next steps are to replace all the caps/resistors on the board and reflow the major chips.

 

Dead ppu chips common fault with snes.

 

any way to isolate the issue apart from swapping out chips?

also forgot to mention I disabled the cic and there's no difference.

 

Are you getting audio? If so, it sounds like you're having the same issue as me, I'm suspecting the big capacitor is dead.

 

No audio either, the big cap was reporting voltage just fine.

 

Are you getting connectivity with it? I did a connectivity test with the mainboard I'm having trouble with and didn't get a response, while I did with a board I know works. I'm a total amateur when it comes to electronics, but methinks that's not a good thing.

 

a capacitor with connectivity is going to be a bad thing

I had the system running and I checked the voltage across the two points of it.

 

I'm able to get a voltage reading from the capacitors even when the board's been disconnected! The working board has a lower reading than the non-working board interestingly enough.

 

You should do it while it's powered on and compare. The reason there's still power after is cause it takes some time to fully lose the charge, it can still give you a big zap at that point, so be careful.

 

Just like the NES. Flick the switch on until the LED turns off.

 

There is no "big zap" to give you inside a snes.

 

It *is* possible to create a short and blow the picofuse though Hence why you're suppose to switch it on after the power has been disconnected, though I've still seen sparks even after doing this.

 

Yes, the picofuse is quite easy to blow. Its a good idea to keep spares on hand (ideally that are resettable)

 

picofuse being the one near the 7805? I think I need to replace some caps, the readings are higher vs actual working Repair, Restoration and Conservation/Preservationconsole.

 

yes, but if the power light is coming on - its not the picofuse.

 

You can also replace the picofuse with an equivalent glass fuse. Much cheaper and much more available. But yeah, if the red light is coming on, it ain't the fuse.

 

On all these years repairing US SNES and Super Famcons, I only remember replacing PPUs twice, maybe three times.

The most chips I used to replace were the Work RAM (S-WRAM it's either from Sharp or Fujitsu) and the CPU (aways a Ricoh part).

This is one of the cases I had to replace a PPU chip:

http://nfggames.com/forum2/index.php?topic=2916.0

I still have that Super Famicom and it works like a champ.

 

l_oliveira, anywhere where I can buy the Work RAM or CPU? If it means requiring another SNES I'll just pass it on or keep it for spare parts I guess.

 

The only source for CUSTOM parts which are produced specifically for registered/trademarked/copyrighted products are the product itself ...


Still you can even have other faults cause it to not boot, like for example broken traces.

 

yeah I see your point - how'd you figure out it was WRAM in that SNES, possible without replacing it? What symptoms did it have?