Difficulties with powering my Yobo

[MisterPal]

First off I would like to extended a hello to everyone on the ben heck forums.

Now onto onto my main problem, I am currently attempting to create a portable from a Yobo I have had for several years now. The battery I am using for this is 9.6v NiMh battery. I have managed to connect said battery to the Yobo through where the power plug thing previously was. When I attempt to turn on the Yobo with the battery plugged(with or without a cartridge) I do not get a response from the blue led that lights up when it is turned on. When I checked this with a multimeter I found that there was no power at the ciruit board where the led was located. I am fairly new to this and i figured that someone might have a helpful suggestion.

Thanks

[Metallica Man X]

Hey, welcome to the benheck newcomer!

The power pack for the yobo actually outputs way more than 9v for some reason, that might be why it doesn't work when you run the battery through the power plug--there isn't enough juice going through it. I dunno if it's exactly the same for all yobo types, but mine put out close to 12 volts, and when I tried using a 9v battery, I got nothing.

However, the yobo itself is powered by the +5 volt coming from the 7805 regulator, find that wire and hook 5 volts to that and see what happens.

[MisterPal]

Thanks for the advice I really appreciate it.

[Kurt_]

Seconded. Just make sure you connect it to the correct pin. Avoid the middle one, use a regulated 5 volt power source, and solder it securely without bridging anything before you turn it on, and the worst that could happen is that you don't get it to start up, in which case you use the other outside pin on the 7805.

If this is the top:

_______
L7805
TOP
_______
| | |
| | |

Then the pins are in this order:

IN / GROUND / +5V OUT.

[XCVG]

Just feed the power into the leftmost leg of the 7805. That should work, unless it's a super-high-dropout version.

[MisterPal]

Anyway to tell the difference?

[Metallica Man X]

The only way I can think of is to just use your multimeter, and see how much power comes out of it when the pack is plugged in.

[MisterPal]

Sorry i don't think I was clear with my last post what i was trying to ask is does the super high dropout version output lots of voltage or very little?(ie 3-4 volts or 16-18 volts)

[XCVG]

Sorry i don't think I was clear with my last post what i was trying to ask is does the super high dropout version output lots of voltage or very little?(ie 3-4 volts or 16-18 volts)

Dropout refers to how much higher the input voltage has to be compared to the intended output. What we have here is a 7805 regulator, which outputs 5 volts. An LDO (low dropout) regulator may only need 6 volts in. Most 7805 regulators will work fine with 7 or 8 volts. More than that and you risk blowing the regulator depending on the load. This is because a 7805 and any other standard linear regulator lowers the voltage by dumping the excess as heat. So as the input voltage increases, the heat output increases for any given load. Basically what I'm trying to say is that it'll get hotter at 12 volts than at 7 volts. As you probably know, heat kills electronics. The regulator will also blow if you try to pull too much current through it, though you shouldn't have to worry about that with a Yobo.

Let's say this is your 7805. You need to feed power into the leftmost pin on this diagram. The middle pin is ground, the right pin is output. You can connect your negative lead to the middle pin, by the way. The metal tab on top works, but it is probably cut off. The pinout for most regulators is in, ground, out. The metal tab is usually ground as well.
_____
| |
|_____|
| |
| |
|_____|
| | |
| | |
/\
here

EDIT: Argh it glitches all my ASCII drawings!

[MisterPal]

Thank you very much for the advice I assume I wouldn't risk a complete meltdown then with 9.6v then? Fortunately though the metal tab at the top with the "o" in the middle is there so i will attach the black wire to that then.

[XCVG]

Thank you very much for the advice I assume I wouldn't risk a complete meltdown then with 9.6v then? Fortunately though the metal tab at the top with the "o" in the middle is there so i will attach the black wire to that then.

Probably no meltdown with 9.6V. And yes, the black wire can go to the tab, the red one goes to the leftmost leg (as stated a zillion times before).

[MisterPal]

Well thanks for evrything then I am quite grateful to everyone for their assistance and I should get cracking at hacking up my yobo some more.

[MisterPal]

I hate to bring up this topic again but after hacking up my yobo I finally got it working(except for sound) on Sunday after I found some time to work on it. The screen worked perfectly fine but on Monday evening when I hooked up the battery I was using to power the screen the screen It refused to power up. I hadn't touched anything and the battery was only 8v. Could anybody help figure out what could be wrong with my screen.

[Metallica Man X]

Kind of a stupid question, but is the battery fully charged?

Otherwise, I'd check all the leads, and make sure nothing got moved into a bad spot, and also make sure you're using the right connections too..sometimes it's easy to get your wires crossed, and not notice.

[MisterPal]

Kind of a stupid question, but is the battery fully charged?

Otherwise, I'd check all the leads, and make sure nothing got moved into a bad spot, and also make sure you're using the right connections too..sometimes it's easy to get your wires crossed, and not notice.

The battery is fully charged. I could check the leads but as I said beforehand they were perfectly fine and I didn't move so much as to get them crossed.