trouble getting mini SNES working

[chronomitch]

Hi. I started working on making a portable SNES, but I can't seem to get my mini SNES working.

I managed to LED mod a PS1 LCD and hook it up to some batteries (2 x 3.7 li-poly batteries in series. I know it works because I was able to get it to turn on and work the volume and contrast controls.

For the mini SNES part, I have been using Ben's book to get everything hooked up properly. So far, I have removed the motherboard from the case, removed the AV and DC jacks (back panel), and removed the reset and power buttons.

The only wiring I have done for the mini SNES is:
1) a small wire connecting the two points near the power switch so it is always on.
2) a +5 volts wire from the mini SNES to the lower 7805 regulator on the PS1 LCD which is also powering the LEDs.
3) a wire from the mini SNES ground to the recommended ground on the LCD (the spot just to the left of the screen). This ground spot is also connected to the LEDs and the negative poll of the batteries.
4) a wire connected the composite video out of the SNES to the composite video in on the LCD.

These are the only wires running to/from the SNES. I have not done any wiring for sound yet. I have one controller connected to the controller port and a game plugged in (Super Mario World). When I turn on the LCD (which should also turn on the SNES), I don't get any video from the SNES.

Is it possible I somehow fried my mini SNES? Do I need to have the sound wired for it to work?

Thanks.

[Kurt_]

1) Connect the +5 volts to BOTH sides of the mini snes 7805 regulator spot (NOT THE MIDDLE GROUND). For some reason this fixes lots of problems. (You can also save some power by connecting this point to a 7805 on the screen board, and removing the SNES's 7805 altogether. But do this after you've fixed the problem)

2) Removing the A/V Jack should be your last thing. This way you can hook the system up to a TV to check it works when situations like this pop up. For future reference.

3) Make sure you've hooked up the composite wire to the correct spots on the SNES board (ie. you weren't just blindly following holes numbered in the book and connected the wire on the wrong side of the board) and the PS1 screen.

4) The sound is separate, you can run the entire thing without it.

5) Yeah, it's possible you fried the SNES. But if you were careful, and didn't put it on metal or the PS1 board when you turned it on, you should be okay. If you accidentally connected +5/+7 volts to ground and turned it on, it's likely fried. To answer this question completely, you'd need to give us more information about what you've done to the SNES and what sort of conditions it has been worked on in.

[chronomitch]

1) Connect the +5 volts to BOTH sides of the mini snes 7805 regulator spot (NOT THE MIDDLE GROUND). For some reason this fixes lots of problems. (You can also save some power by connecting this point to a 7805 on the screen board, and removing the SNES's 7805 altogether. But do this after you've fixed the problem)

2) Removing the A/V Jack should be your last thing. This way you can hook the system up to a TV to check it works when situations like this pop up. For future reference.

3) Make sure you've hooked up the composite wire to the correct spots on the SNES board (ie. you weren't just blindly following holes numbered in the book and connected the wire on the wrong side of the board) and the PS1 screen.

4) The sound is separate, you can run the entire thing without it.

5) Yeah, it's possible you fried the SNES. But if you were careful, and didn't put it on metal or the PS1 board when you turned it on, you should be okay. If you accidentally connected +5/+7 volts to ground and turned it on, it's likely fried. To answer this question completely, you'd need to give us more information about what you've done to the SNES and what sort of conditions it has been worked on in.

Thanks for the info. I forgot to say that I already removed the 7805 from the SNES. The +5 spot on the SNES is already wired to the 7805 on the PS1 LCD I'm using to power the LEDs.

I tried temporarily bridging the two points (not the middle) where the 7805 on the SNES used to be. This should give both points +5 volts. Unfortunately, when I did this and turned the system on, the LEDs on the PS1 LCD did not come on.

I checked the +5 and ground points on the SNES using a voltmeter, and it registers at +5 volts.

I can only think of two possible sources of this problem:
1) I hit the ground when I was soldering the switch contacts to be permanently on. (I don't think I did this.)
2) I applied too much heat to the pcb when I was de-soldering the AV connector.

[Kurt_]

The A/V connector shouldn't be much of a problem. Nothing major is located near there, as long as you didn't rip up any traces.

Now stop jumping to conclusions!

1) Is the video on the LCD black or blue. If I recall, blue means the LCD is on but not getting any video, and black could be a few things. Here's some fixes:

Blue: The ribbon cable on the back of the LCD module is not connected properly. Make sure it's all the way in and such.

Black: Is it ALL black (ie do the LEDs come on?) If the LEDs don't come on, that's likely to be your problem. Either get them working or use a flashlight to check if there's video on the screen but no backlight. Remember you can only hook up LEDs one way.
If the backlight comes on, then it could be lots of things. You're testing all this with a game that's known to work always right? Give the game a quick cleaning and try.

2) Double check all your connections are connected to the proper spots. The video on the SNES is connected to pin 9. Using a multimeter make sure you're getting a voltage from it, you might have torn a trace or connected something weird.

[chronomitch]

The A/V connector shouldn't be much of a problem. Nothing major is located near there, as long as you didn't rip up any traces.

Now stop jumping to conclusions!

1) Is the video on the LCD black or blue. If I recall, blue means the LCD is on but not getting any video, and black could be a few things. Here's some fixes:

Blue: The ribbon cable on the back of the LCD module is not connected properly. Make sure it's all the way in and such.

Black: Is it ALL black (ie do the LEDs come on?) If the LEDs don't come on, that's likely to be your problem. Either get them working or use a flashlight to check if there's video on the screen but no backlight. Remember you can only hook up LEDs one way.
If the backlight comes on, then it could be lots of things. You're testing all this with a game that's known to work always right? Give the game a quick cleaning and try.

As I said before, the LEDs seem to be working fine. The screen is dark but definitely lit. I can easily seen the green contrast and volume bars if I press their respective buttons. I checked the ribbon cable and reattached it. No change.

I have tested several games. All work on my older version SNES and used to work on the mini SNES before I hacked it out of its case.

2) Double check all your connections are connected to the proper spots. The video on the SNES is connected to pin 9. Using a multimeter make sure you're getting a voltage from it, you might have torn a trace or connected something weird.

I rechecked the +5, ground, and video connections using Ben's book, and everything seems to be in order. As for the multimeter, I'm getting some strange behavior. I placed the positive pole on the video line and the negative poll on the ground. As I was taking readings, the voltage dropped slowly but steadily from about 2.75 volts down to 0. I rechecked the +5 volt and ground lines on the SNES, and I'm still getting the needed +5 volts.

While I was at it, I decided to check the power switch contacts against ground using the multitmeter -> 0 volts. I must have torn a trace or something when I was removing the switch.

I ended up buying another mini SNES on ebay. I'm going to try to be more careful this time around and do more testing before I remove parts. Better luck next time I guess.

Thanks for the help.

[Kurt_]

Yeah, that's the way I did it. Five later and I had a portable! (Well, maybe three, I don't remember)

One last question: Did you rewire the capacitors like in Ben's book? Because that voltage drop problem sounds like you didn't wire one properly, and it was draining through the multimeter. If you did/even if you didn't, resolder all the connections to the capacitors. The blue/black ones, not the surfacemounts.

More importantly, you've learned not to blindly follow instructions. Although I admit, in the beginning it all seemed so confusing and I didn't know where to start. From experience, you learn. With that, you can make your own build plan. As for a final product, I tried many configuration with the mini SNES and the best was like it was in the book.

But MOST importantly, don't give up. I was extrememyl discouraged by the end of my build, but it was worth it to have something up and running. Looks great on an resume related to engineering too.

[chronomitch]

I haven't rewired the capacitors. However, I looked more closely at the capacitors, and it seems like I burnt the last one on the right with the soldering iron (a little plastic on one side is burnt off). I somehow doubt that this would have killed the capacitor, but my electronics knowledge is limited.

I'm going to try to be more patient from now on so I don't make the same mistakes.

[Kurt_]

Well, there's an easy solution to that one. Take it off, and swap it with a capacitor of the same rating. Right now, this SNES is your "learn how to troubleshoot" SNES. It'll save you screwing up a future one.

[chronomitch]

Well, I received my second mini SNES, made similar connections, and had the same exact problem. Because I was careful this time, I knew there was a problem somewhere with the connections I made, rather than the board being fried.

Then I had an idea. Why not connect the ground from the power jack to that of where the SNES's 7805 used to be? I bridged the connections, and I got video!

The two arrows point to the connections I bridged.

[ShockSlayer]

Great!

Also kurt_, I know what you mean about "5 later!" Although that was only for my first portable; havent missed a single one since!

SS

[Kurt_]

So now you have two working mini SNES?

[chronomitch]

So now you have two working mini SNES?

I haven't wired up the first one yet, but I think I can pretty much assume that it had the same problem.

I'm just surprised that those two grounds (one for the 10v DC jack and another for the 7805 regulator) weren't bridged in the first place. On second thought, they probably were before I removed the metal bracket which was connected to the SNES's original 7805.