SNES suddenly has no power

[Xavier]

Hi everybody! I'm new here! Before I begin let me say a few things about my experience: 1st of all, I just bought a digital multimeter and don't yet know much about it. 2nd, I can't read a schematic. 3rd, I know next to nothing about electricity, other than to respect it. 4th, working with electronic components is still very new to me (just a hobby), so feel free to dumb things down for me or treat me like an idiot if you sincerely think it will help. :) Anyway, so here's the story: My SNES console WAS working with no problem except that it needed a new power port because the old one was broken. So I bought a new one and soldered it in. At 1st I didn't have any desoldering tools (but now I do) except for a soldering iron but I was able to get the old one out. Soldered the new one in (after accidentally bending the pins a bit) and started it up. No power. At some point while doing this repair the fuse had blown. Replaced it with a brand new fuse but still now power. Double checked it, fuse is still good. Checked the power port with my multimeter and the pins have continuity. Switch is good, fuse is good, known working power adapter. The only thing that stands out is that when I turn the console on the red light flashes for a split second before going out. If I turn it off and leave it off for about 30 seconds and turn it back on again, the same thing happens. I can do this over and over with the same result. So somewhere it's getting power but just not keeping it when I turn on the console. Any help would be greatly appreciated! Thanks in advance!

[RP2A03]

Try measuring both the input and output voltage on the voltage regulator. The voltage regulator is the squarish black box thing with three pins right near the fuse. Left pin is input, middle is ground, and right is output. Set your meter to DC voltage and with the power to the SNES switched on connect the red probe to the left pin of the voltage regulator. Next, connect the black probe to the ground plane of the SNES. Note the voltage reading and repeat for the output.

If you have no voltage going into the voltage regulator; then test the components upstream. If you have about 9V going into the regulator and anything other than 5V coming out, then replace the voltage regulator with a new 7805.

[Xavier]

Input is about 1.584V and output is about 2.3V. Don't know if that is too high or too low but the 2.3V is low if it's supposed to be 5V like you said. I've heard the maximum allowance is a difference of 10%. Anything beyond that means it need replacing, right? Didn't test the upstream because I don't know that that means or where to find it. Again, noob here. Is there supposed to be continuity between the input and output? My multimeter doesn't beep or give a reading for it.

EDIT: Tested continuity on the working console and no, there not supposed to be continuity between the input and output. Good to know.

[Xavier]

Just tested the voltage of a working SNES console (though it has the black screen of death) and the input is about 11.45V for the input and about 5.04V for the output. So I guess the conclusion is that the voltage regulator is bad and needs replacing. Just ordered a couple and once they come in I'll solder one in place and see what happens. Thanks RP2A03 for the help! Will update when they come in.

[RP2A03]

The voltage reg is not outputting enough because it is not getting enough. The problem lies somewhere before the voltage regulator.

[Xavier]

Doh! Now don't I look like an idiot. Ok, lesson learned: don't jump to conclusions. But it makes me think that it has something to do with the new power jack I put in then. If it was fine before I replaced it but now it's not, then logic suggests that that's the culprit. Tested the voltage of the power jack on both the working console and the nonworking console and got 2 very different readings. The working console says 10.8V but the non working console says 0V. Took a pic of where I tested it at. Maybe I bent the pins badly enough that they aren't getting a good enough connection?

8437

EDIT: Not the power jack. Swapped it with a working one and still nothing. Although it makes me wonder: when I removed the old jack, I cut the metal clip showed in the picture just because it was faster than unsoldering both points and I was throwing it out anyway. Is it possible that the jack retained some electrical power and that when I cut that piece it released it into the motherboard thereby frying the whole thing? But wouldn't the blowing of the fuse have stopped it? This thing is really frustrating me....

[RP2A03]

I cut the metal clip showed in the picture just because it was faster than unsoldering both points and I was throwing it out anyway. Is it possible that the jack retained some electrical power and that when I cut that piece it released it into the motherboard thereby frying the whole thing?

No. Capacitors store charge, not metal clips. Most likely you discharged the big cylindrical thing (capacitor), causing it to dump its entire load all at once into the fuse. Switching the SNES on for a few seconds after unplugging it would have prevented this. The motherboard is probably fine.

Also, I am not entirely sure what you mean by "metal clip" unless you are referring to the pins, or why cutting it would be faster than desoldering since you need both holes to be clear in order to solder in the new jack. In any event, you should measure the voltage across the jack before the solder joints in addition to after the solder joints. If you have no voltage before the solder joints then the plug is not making proper contact with the jack. If you have no voltage at the solder joints then you made a cold joint and need to resolder.



If you need help soldering:

https://learn.adafruit.com/adafruit-guide-excellent-soldering/making-a-good-solder-joint
https://learn.adafruit.com/adafruit-guide-excellent-soldering/common-problems



Electricity basics:

https://learn.sparkfun.com/tutorials/voltage-current-resistance-and-ohms-law



Reading a schematic:

https://learn.sparkfun.com/tutorials/how-to-read-a-schematic

[Niku-Sama]

I would check the bottom of the board and see if there aren't any cold or broken (linky) (https://en.wikipedia.org/wiki/Soldering#Cold_joint) soldering joints

[Xavier]

Thank you for being patient with me! The links you provided are really good stuff! I'll have to sit down for a while and look them over and "educate" myself a bit. :)

Yes I did mean the pins when I said "metal clips." And why did I cut them to remove them? Long story short: seemed like a good idea at the time. I will continue to mess with it and see if I make any progress. Maybe my soldering is bad. I did use a rather old flux that doesn't even look any good IMO. Will also carefully inspect the bottom of the board for cold solder joints.

But while I was thinking about it, I remembered a crucial detail that I cannot believe I had forgotten. When I first soldered the new jack in, the console DID work. I tried 3 games in it: 1st was F-Zero, which started up with no problem. I then shut the console off (didn't rip it out while power was still on) and took it out. The 2nd game I put in was Gradius III and that worked too. But when I tried the 3rd game Doom is when the console suddenly wouldn't power on anymore and no other games would work either. I think I just assumed that my soldering job was bad and tried redoing it which probably led to the blowing of the fuse because I didn't think to discharged the system. Don't know if that helps but like I said I'll keep at it until either I figure it out or give up.

EDIT: Thinking it's the D1 diode. Need a new one either way as I just killed it on my other SNES console.

[Xavier]

I got the second console back up and running :D Jumped the D1 diode with a wire until the new diode comes in, though I've been told I don't necessarily NEED a diode in there. But for a couple of bucks, why not add the extra security? Luckily that's all that went bad on it. Now to go back to the first console which was the whole reason I started this thread. Gonna try jumping the D1 on that too and see what happens.

[Xavier]

SUCCESS!!!! GOT IT WORKING AGAIN!! HURRAY!! Turns out the D1 had blown. Needs a replacement diode, which is in the mail. Want to extend a special thanks to RP2A03 for his great knowledge :hail: and for saving me from spending money on unnecessary things because of my own ignorance and stupidity. You sir are a legend to me! And I now know a lot more about electronics and circuit boards than ever before. Plus I got to improve my soldering skills :)