Sega Megadrive Model II portable - project worklog

[flax]

Hi!

I'm posting now without that much to say really. But I look at this as the first step in the project, if I get you guys excited I have one more reason to finish this project

I don't have that much experience with this kind of work. All I've done is NTSC/PAL, 50Hz/60Hz and overclocking mods to my SMD model 1 (yes it is the high def one and I do love it). I've also made my own chords, RGB for model one and my 32x, and the link chord for the 32x.

So I have some basic soldering skills and I kinda understand electronics.

I'm going kind of basic. I wont mold the case or create my own controller and such. I'm going to use:

SMD model 2
PSone screen
Honeybee 6 button turbo controller
and I think I'm going to build the case out of plywood

It will be kind of big, but that's ok considering this is my first portable, it will be easier to get it together.

I'm going to cut down the board as much as I can. But that wont be much, because I don't want to move components.

a rough sketch of the build:
(by rough I mean rough, your eyes will probably bleed)
http://i35.tinypic.com/2884mf5.jpg" onclick="window.open(this.href);return false;

so, basically I'll just put all the components in a wood case.

The big steps are pretty much:

Crop the Megadrive board
Crop the PSonescreen
LED mod the PSone screen
Create the low battery indicator.

Then its just a matter of getting everything to fit.

I might add a second player port. but I have a hard time to see the meaning of that, if I want to play with a friend, we'll just play on my system that is hooked up to the tv.

That's pretty much it for now. I can't start the work right now, I have to get home to my parents and get the stuff.
For now I will read as much as I can, and try to plan everything.

Almost forgot, I have to get a battery and a charger as well. First I wanted to go with many AA batteries, so that I could put regular batteries in if I don't have time to charge. But I think I'm going to go with battery-pack and a charger.

I kind of started this project this spring, but I just never came to it. I bought the screen and did some reading. And I've forgotten pretty much everyting

Ok, THAT'S it for now. I'll come back with updates and/or questions

Cheers
//flax

[flax]

Hello again.

Anything wrong with this crude mockup?

http://i36.tinypic.com/2w1xqmw.jpg" onclick="window.open(this.href);return false;

Will a LED moded psone screen run of 7,2v?

I've been looking at a RC-rack with 6x http://www.kjell.com/filarkiv/SUPPORTPD ... /42546.pdf" onclick="window.open(this.href);return false;
should be enough right? to run a genesis portable for a fair amount of time.

[argelfraster]

Im not sure about everything you asked because im not familiar with the Megadrive ( or any sega system )
But yes, the psone screen will run off 7.2v.

[flax]

But yes, the psone screen will run off 7.2v.

Ok, sweet. Will have to get a battery soon

http://i35.tinypic.com/a9s86x.jpg" onclick="window.open(this.href);return false;

A new schematic. its a work in process though.

I can keep the headphone jack right? I've seen that a lot of people don't get any sound until they short the headphone-pins. Is that only needed if you remove the jack? Would be nice to be able to keep it.

I should get the stuff later this week. Going to go and get some plywood or something tomorrow. Cant really start with the case though until I get the components.

I think I'm going to fit the speakers on the side of the case, and the headphone-jack on the bottom.

One problem though is going to be to paint it. I've sanded down the controller. But the a b c x y z buttons are still on there. Will have to see if I can cut the buttonholderthings so that I can put them back on when its painted.

EDIT: I think I have come up with the perfect name for it. It's a Sega Megadrive, it's handheld, its gonna be huge: The Mega Hand!

[argelfraster]

love the name
Yes, if you keep the headphone jack you don't have to short the pins.

[flax]

Been looking at some batteries from kjell.com (Swedish electronic store).

I don't quite understand how you charge different types of batteries.

The once I've been looking at are:

7.2v NiMH RC-acc
It's a six-cell construction
http://www.kjell.com/content/templates/ ... item=42509" onclick="window.open(this.href);return false;

Will this charger work without any other components?

http://www.kjell.com/content/templates/ ... item=44135" onclick="window.open(this.href);return false;

Constant powercharger with automatic battery-pack recognition. Works with battery-packs between 1 and 10 cells. Adjustable charging power: 50, 80, 120, 180, 240 or 300mA. Protection against miss-polarization, overheating and shorting. Is delivered with RC-plug, DC-plug and battery clamps.

(sorry if something doesn't make sense, not sure about all the English translations)

[argelfraster]

The plugs of the battery and charger are different.
you would need something like

[flax]

Ahh, ok. I thought that the plug on the battery was a male.

But would it work if hacked em up? And used some plugs that match? It wouldn't like burn up or something because of overcharging?

thanks for the help argelfraster

[argelfraster]

You could connect a new plug to the charger, but you will want to get a 7.4v protection circuit.
Like this

[flax]

That one is for Li-ion and Li-Po batteries. Can't find an equalivant for NiMh's. Is it needed for NiHms?

cheers
flax

[argelfraster]

Li-po's are better than NiMH's.
Get some li-po batteries.

[flax]

bought a battery and a charger now. Ended up with a NiMh pack. Mainly because I couldn't get my hands on a cheap NiCd pack

http://www.kjell.com/content/templates/ ... item=44135" onclick="window.open(this.href);return false;
http://www.kjell.com/content/templates/ ... item=42509" onclick="window.open(this.href);return false;

Tried the battery without load on my multimeter, it read like 7,4v. Hooked it up in the charger, and it is making this high pitch humming sound, is that normal?

The charger only goes up to 300mA so I guess it's going to take a while to fully charge it if it's all out.

But there shouldn't be any problem with overcharging right? The charger is going to take care of that right? Don't want the thing to blow up on me... There's a red LED on the charger that turns on when I plug it in the wall, is that one going to turn of or something when its done?

Sorry for the noobish questions, but I've never handled these kind if batteries or chargers.

EDIT: Sigh... Done some research now, and I think that this isn't a smart charger, it wont shut of when the battery is fully charged. That sucks. Have to go back to the store and see if I can get a refund. Because I asked the seller if it would shut of and stuff, and he said it would. They sell a smart charged there but its like $10 more, and at another store here they sell good chargers for the same price as the one I have. blah bla blah [/whine].

[flax]

No updates yet. Going home next weekend to get all the stuff though. So the project will be up and running next week.

Got the right charger today, but I have one question.

My battery-pack have 6 cells, and its rated at 7.2V.

I can set the charger to 2, 4, 5, 6, 7, 8 or 10 cells. But on the back it says that the 6 cell setting is charging at 8.4V, the 5 cell setting is charging at 7.0V. Which setting should I use?

Can I set the amperage to 1000mA or should it be at 500mA?

[/end stupid questions]

thanks in advance.

[marshallh]

Set it to 6 cells. If the charger was only supplying 7.2v to the pack, there would be hardly difference in voltage and it would never charge.

Use 500mA whenever you can, but it should be fine with 1A if you got a good pack. It's common for RC racers to charge their packs at 3.0-3.5 amps (they also use more expensive delta peak smart chargers)

[flax]

Set it to 6 cells. If the charger was only supplying 7.2v to the pack, there would be hardly difference in voltage and it would never charge.

Use 500mA whenever you can, but it should be fine with 1A if you got a good pack. It's common for RC racers to charge their packs at 3.0-3.5 amps (they also use more expensive delta peak smart chargers)

Ok, thanks.

Got everything at my place now. So the work will start this week.

First out is cropping the board. What kind of tools should I use? Been thinking about getting a dremel, would that be ok or can the board take damage?

Then i'm gonna LED mod the PsOne-screen and then its just a matter of wiring everything.

Been thinking about the case aswell. I have a spare SMD model 1 chassi and it would be awesome to use the original switches from that, like the volume, on/off and reset button.

This is gonna be one hell of a franken-casing. =P