Bacteria's Multi-Platfrm project - Phase 2 - SNES

grossaffe · Post by **grossaffe** » Sat Jul 12, 2008 9:35 am

a fan? is that really necessary for an SNES?

phantom92opera · Post by **phantom92opera** » Sat Jul 12, 2008 9:38 am

7805 lets off heat. its just a precaution

bacteria · Post by **bacteria** » Sat Jul 12, 2008 12:33 pm

My logic is that the SNES came with two metal plates to remove heat from the system. One was over the chips but not actually on them, so they must generate a little heat, however the other metal piece is attached directly to the 7805; which of course converts extra voltage into heat when reducing the voltage down to 5v. The 7805 will need a heatsink therefore and air in and out to keep everything cooler; so it therefore seems appropriate to use a fan to do this. If heat wasn't an issue at all, there would be no vent holes in the SNES casing - some consoles don't have venting holes after all.

Valium · Post by **Valium** » Sat Jul 12, 2008 12:41 pm

The holes in the case are there because that's all they ever needed. The majority of our screens have 7805's in them, and they've never needed fans.

bacteria · Post by **bacteria** » Sun Jul 13, 2008 7:40 am

So I can just get away with a few vent holes in the case, and a heatsink on the 7805 on the SNES board then??

Valium · Post by **Valium** » Sun Jul 13, 2008 8:22 am

Yes, and it'll work just fine.

bacteria · Post by **bacteria** » Sun Jul 13, 2008 8:31 am

Thanks, that will save a little work then!

ShockSlayer · Post by **ShockSlayer** » Mon Jul 14, 2008 12:17 pm

grossaffe wrote:
ShockSlayer wrote:Although I already know that this thread will always be at the top of the forum and will probably span 15 pages of just your updates, I can clearly see that this one will happen quite fast.

So far we know that you rmoved the case and have begun flattening it. Looks good so far, I mean, its not like I havent seen a naked snes before.

SS
that's about all you've seen naked!

Coming from you, sure, lets go with that.

I've seen a lot of consoles naked.

SS

bacteria · Post by **bacteria** » Tue Jul 15, 2008 8:18 pm

Query - perhaps some bright spark can answer this please!

Thought I would double check which of the connectors for the power-in points on the power plug was positive and negative, so I didn't hook up my power the wrong way around. Simple, normally the negative on the power is the same as the negative (ground) on the board - nope. Ok, tested with multimeter with power on, virtually no current (?), checked on the power supply plug itself, still nothing (?). Ok, resorted to logic - plugged power supply in, turned system on, all fine. On the 7805 I was getting 12v in and 5v out, but still no voltage on the power line. Strange. Plugged a battery pack of 7.4v onto the 7805 input and negative on grounding strip. System fine.

Out of interest, because everything works (even after removing expansion pack, unneeded), it works, which is fine, but my questions are thus:

1) Why zero volts on the power in plug yet system has voltage?
2) Why does the SNES up-step the voltage to 12v when it doesn't seem to need to as the 7805 is happy with 7.4v and the system works?
3) When connecting directly to the 7805, the system on/off doesn't work anymore (must be by-passed), always on. When the batteries are removed and the system goes off, the capacitors don't seem to keep any voltage, as they did before.

Comments appreciated!

phantom92opera · Post by **phantom92opera** » Tue Jul 15, 2008 8:23 pm

i had this same thing happen w/ my genesis p ( i hooked straight up to the 7805) and noticed the capacitator thing.

bacteria · Post by **bacteria** » Tue Jul 15, 2008 8:43 pm

Interesting, not just the SNES then.

It would be interesting to know why this happens.

I know before I asked if a lower capacity capacitor could be used instead of the 2200uf one, it was indicated that I could, although I can't remember how low to go. As the capacitor isn't needing to discharge when the system is off (light doesn't come on for a second when power removed), does this also indicate a lower capacity capacitor is better anyway, so there isn't a delay initially while the capacitor charges up??

bacteria · Post by **bacteria** » Thu Jul 17, 2008 3:13 am

Making good progress on system, had half an hour yesterday for project work and a couple of hours this morning (about an hour left before I need to stop for the day).

Probably easier to document work like this:

Completed before:

* Relocated large capacitor.
* Running system off batteries.

Newer work done/doing (all documented fully):

* Removed the plastic controller ports from the controller input mobo.
* Removed plugs from SNES and controller input and controller input mobo, to relocate.
* Worked out how everything will fit in case.
* Opened up SNES controller, need to wire directly to the controller input board.

Once those parts are relocated, I will test the system again to make sure all is fine, then remove the reset switch, remove the video plug; relocate the cart slot; then wire the SNES to my system, test RGB; build case: job done!

bacteria · Post by **bacteria** » Mon Jul 21, 2008 6:57 am

Here is what the guts of the system look like at the moment. I had to trim some of the grounding on the SNES mobo and also what I could from the controller mobo, so it all fits. I am aiming to get the handheld sections to 8mm thick, this includes 2 pieces of 2mm perspex; innards 4mm.

Key (arrow colours):

Orange - wires connecting controller input mobo to the controller.
Pink - connectors to communicate power and controls to the screen/controller section (other system half).
Grey - remains of removed expansion port.
Cyan - power connections (from batteries).
Yellow - video and audio connectors.
Dark blue - relocated capacitor (1000uf).
Mid green - cart slot needs relocation.
Purple - removed reset button.
Dark green - SNES to controller input relocated.
Black - areas of board reduced in size (grounding strips).

I am hoping to get this finished and have enough time to finish one or two systems for the competition in time, should be fine.

I have decided to try and keep this project transparent (top view), for a change; hence I am being careful to make all the wiring neat. Project updates on my site, as normal.

bacteria · Post by **bacteria** » Mon Jul 21, 2008 9:23 am

Further update - relocated the cart slot. Tested system, works nicely!

Jobs left - wire the power and controls from the system to the two contact boards to the screen and controllers section; build the case; (wire the video to RGB).

bacteria · Post by **bacteria** » Tue Jul 22, 2008 3:00 pm

Right, got everything wired up, including RGB on my PAL system. The diagrams I have seen are wrong, pin 3 on the PAL system is voltage, pinouts suggest using a 75R resistor and connecting C-Sync to the composite, found using a 70R resistor far better, and, no need for 47R resistors on the RGB lines are needed.

Rewired part of the system, not uploaded pics yet, hope to tomorrow. Spent several hours yesterday and today on wiring everything up. System is very flat on the handheld areas, about 4mm thick (thickness of a flattened board and a wire), plus two sheets of 2mm perspex = 8mm total.

One issue - after a few minutes, or several, the system goes off. I am hoping this is due to my batteries needing charging, in process of doing this now - if it isn't I can only think that 7.4v going into a 7805 is a bit low, in which case I will use a TI card to get 5v and pump that into the output pin contact where the 7805 is (after removing the 7805 of course) to get more efficient voltage. Will keep you posted.

Any ideas?

I am pleased to report however that all the controls work fine, had several sessions of playing Tetris Attack.

RGB seems a bit better than composite on the SNES, so has to be worthwhile using RGB.