Expansion pack relocation... has anyone tried this before?

timmeh87 · Post by **timmeh87** » Thu Dec 01, 2005 10:34 pm

well. after studying the nintendo 64 and the inside of the expansion pack with my eyes and a continuity tester for about an hour, i have decided to attempt something rather ambituous.

the place where the expansion slot is soldered to the board is exactly the same shape as the piece of ram that is contained within the expansion pack. this piece of ram, in turn, is exactly the same as the two pieces soldered on below the expansion pack slot.

almost all the pins on the 3 pieces of ram are connected together. about half the pins go to ground and 3.3v, and the other half go the the big CPU chip right underneath the vertical row of ram chips.

i am going to attempt to remove the ram chip from the expansion pack, remove the expansion pack slot, and stick the ram where it rightfully belongs. the expansion pack has about 6 capacitors and 3 resistor banks on it, but i believe these to be simply for decoupling. if the pieces on the motherboard are adequately decoupled, and all the pins are connected together, then i probably dont need to worry about them.

so far i have soldered the ram chip out of the pack, and thats it. it was actually quite easy, since almost all the pins are on one side. once the 4 pins on the back are disconnected (easily with the edge of a razor blade while hot), you can slide the razor blade underneath the chip and pry up gently while you try to heat all the pins on the other side at the same time (this is of course AFTER removing as much solder as you can). it came off without much trouble.

https://muss.cis.mcmaster.ca/~bernast/img/ram.JPG

anyhow. im going to bed now. im getting sleep deprived.

ill probably get the pack slot off the board on saturday.

oh yeah, i also mapped all the pins, ill post it later

nos_slived · Post by **nos_slived** » Thu Dec 01, 2005 10:54 pm

What about detection? There must be a way that the system detects whether there's an expansion pack or jumper pak inserted. Also, some additional connection must be required, other wise you wouldn't need a pack in at all times.

timmeh87 · Post by **timmeh87** » Thu Dec 01, 2005 11:03 pm

i dont know how the system does what it does. all im doing is making the wires to the contacts on the chip shorter.

it might be possible that each chip has a unique address (like, every chip ever made has a different one), and there is some sort of serial communication going on between the chip and the CPU. how does a normal comptuer "detect" the ram? do not underestimate how complicated things can be

ALL that the jumper pack is is a piece of ram on a board with a connector. thats it.

as far as needing the pack in at all times, perhaps the system preconfigured to use 3 ram chips, and the jumper pack just shorts out a connection that says "this ram bank is not avaliable". not having the jumper pack in would cause the system to assume ram is present and therefore not work.

its a theory at best. but like i said. all i am going to do is shorten preexisting connections. not make any new ones or break any old ones. it cant fail. unless i botch the soldering job.

Turbo Tax 1.0 · Post by **Turbo Tax 1.0** » Thu Dec 01, 2005 11:09 pm

i think that usbcd wanted to do something similar but all he wanted to do was relocate the expansion pack

Electric Rain · Post by **Electric Rain** » Sat Dec 03, 2005 6:10 pm

Sweetness! You've GOT to let me know how this goes. I wanted to do something like it as well. It should cut down on the thickness quite a bit, no?

G-force · Post by **G-force** » Sat Dec 03, 2005 9:40 pm

Why didn't I notice that! Please tell if this works out. It's quite clever and space reducing.
The soldering is gonna be a bit tricky. But if you're skilled enough, you could probably do it without a problem. Good luck, and may the force be with you! (I've been wanting to say that since I watched SW: Empire of Dreams on TLC the other night

)

cowsgoquack101 · Post by **cowsgoquack101** » Sat Dec 03, 2005 9:47 pm

G-force wrote:Why didn't I notice that! Please tell if this works out. It's quite clever and space reducing.
The soldering is gonna be a bit tricky. But if you're skilled enough, you could probably do it without a problem. Good luck, and may the force be with you! (I've been wanting to say that since I watched SW: Empire of Dreams on TLC the other night )

I saw that on the History Channel.

Yes, please do tell if this works out for the best.

timmeh87 · Post by **timmeh87** » Sun Dec 04, 2005 12:49 am

ok. so. here is another update.

i was studing the expansion pack board, and i noticed that the 3 banks of 4 resistors were connected from 12 different pins to 3.3v. i recognized these as "pull-up" resistors and i got to thinking "uh-oh. those might be important". upon busting open (well, melting) my jumper pack, i found that it had the same resistors. so it seemed that they were nessecary even if there wasnt RAM present! I then referred to the pinout that i had contsructed, and found that the pins being "pulled up" were EXACTLY the same pins that were connected to the CPU (the rest were connected to 3.3v and gnd) so i figured i should keep them! (the resistors) lol.

so i though about how to do it for a while, and even though i didnt want to, i decided that the best way to do it was to solder the RAM chip back onto the pack board, and then solder the pack board onto the motherboard, so that it lies flat. its *almost* the same thing, but it bothers me because i was hoping i could heasink all my 3 ram chips together. but now they will be at different heights.

anyhow. i cut the card egde connector part off of the pack's board, so that instead of a staggered pattern of large pins, i could work with the actual traces themselves, which more or less ran parallel and straight to the chip. i began soldering single strands of some multistranded wire to them. this is where i left off half an hour ago:

https://muss.cis.mcmaster.ca/~bernast/img/ram2.jpg

i plan to double check for shorts/broken connections again tomrrow, when i have a fresh mind or whatever, and then if it all checks out, i will seal it up with some epoxy.

then the easier task of soldering the other ends of the wires to the motherboard

except i ripped 5 traces when i was taking off the pack slot!! so. thats a bit of frustration.

and i hope i didnt freaking fry the ram with static, because i was certianly touching it a lot. i try to ground myself every few minutes, but i dont have a wrist strao.

*o* · Post by ***o*** » Sun Dec 04, 2005 1:27 am

ben tried this 3 times and failed so he remosion pack from his systemved the sion pak from his system

Electric Rain · Post by **Electric Rain** » Sun Dec 04, 2005 1:46 am

*o* wrote:remosion pack from his systemved the sion pak

I'm sorry, but... what?

nos_slived · Post by **nos_slived** » Sun Dec 04, 2005 2:14 am

"Removed the expansion pack from his system".

*o* · Post by ***o*** » Sun Dec 04, 2005 2:23 pm

sorry my damn keyboard doesnt work...

but anyway, i was reading about the psp's ram chip and the traces to that curl around so they are alll exactly the same length could this be important?

timmeh87 · Post by **timmeh87** » Sun Dec 04, 2005 2:52 pm

yeah it could, but im keeping them all the same length anyhow. it might be a bit shorter, but i dont see how shorter could cause problems. the other two chips are real close together

timmeh87 · Post by **timmeh87** » Sun Dec 04, 2005 10:58 pm

k well it dosent boot.

pins 1 and 2 are shorted together on the expansion pack board, but they are suspiciously NOT connected on the jumper board. it makes me think that shorting these two pins indicates the presence of a pack. it dosent boot with them shorted or not shorted.

electrically, the connection between the pack board and the motherboard is fine, i checked like 3 times with a multimeter. all the pins are connected, and no two adjacent pins are shorted.

i have a sort of bad feeling that i fried my ram chip by touching it too much. ill get my spare pack from my girlfriend and swap the chips. ill keep you posted.

id take pictures but im too lazy right now.

(or, perhaps, even though i checked and blasted with compressed air, there might be some metal between two contacts on the mobo. its happened before, and duing the last two days i have produced a fair amount of loose metal...)

if its still not working after i try everything, i can bring it to school, and use the oscilloscope.. i dont suppose anyone else here has access to one, so that we can compare signals....?

nos_slived · Post by **nos_slived** » Sun Dec 04, 2005 11:08 pm

I have access to some oscilloscopes at school, but unless my idiot electronics teacher gets off my back, I may not get a chance to open my N64 and expansion pack up. I have 10 school days until Christmas break, so I will try to do what ever I can. If you start some testing and tell me what you want tested, I'll definitely try my best to get it open this week.