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

timmeh87 · Post by **timmeh87** » Mon Jan 02, 2006 3:46 pm

its possible, im not tryign to discourage you. im just trying to make you think twice before you break something.

take it apart and have a look at the insides. you will see what i mean.

Electric Rain · Post by **Electric Rain** » Mon Jan 02, 2006 4:57 pm

I've got it. *grins* This should work. As I confirmed in my last post, the new N64s use a single 4MB chip, instead of two 2MB chips, to save money. This means that the 4MB chip and an expansion pack can be wired together, (as it is for newer N64s) and two 2MB chips and an expansion pak (as it is in older N64s). So, wouldn't it only make sense that you could use an old N64 board, desolder the two 2MB chips, and solder on two 4MB chips in its place? This would take two expansion paks, (unless you can find a 4MB RDRAM chip somewhere else) but all of the solder points should be all set for both chips. It should be no more complicated than desoldering and resoldering, right? You could remove the expansion pak slot as well, it you wanted. Just make sure that if you keep it there, you don't try to plug in an expansion pak!

Does anyone see why this wouldn't work?

Edit: You would also have to hardwire a "jumper pak" on there if you removed the slot, however.

sniper_spike · Post by **sniper_spike** » Mon Jan 02, 2006 5:34 pm

That sounds like a grand idea! But sadly I don't have the skill to solder\desolder such minute contact points.
Also, are you sure the N64 will recognise the new ram as an expansion pack?
As I understand timmeh connected the ram to where the expansion slot was located, but where the ram is might be a whole different story.

Electric Rain · Post by **Electric Rain** » Mon Jan 02, 2006 6:08 pm

Well, from the looks of things, all three RAM areas are wired in parallel. Those being the two 2MB chips, and the expansion pak slot. So, probably... but I guess there's no way to find out other than to try it, right? Well, either that, or test each and every connection and actually be able to understand the results and what the passives are for in the expansion pak... but frying N64s is much more fun, isn't it?

sniper_spike · Post by **sniper_spike** » Mon Jan 02, 2006 6:13 pm

Oh yes, much much more fun!

timmeh87 · Post by **timmeh87** » Mon Jan 02, 2006 6:57 pm

there are two kinds of components in the pack

1) the capacitors. little beige things use for decoupling...

In electronics, decoupling refers to the practice of connecting localized capacitors close to the power leads of integrated circuits to act as a small localized energy reservoir, which supplies the circuit with current during transient, high current demand periods.
-from wikipedia

2) the pullup reistors. there are 3 groups of 4 resistors if i recall corrrectly. each resistor within one of the little groups is separate; I guess its just a convinient way to attach many resistors in parallel at once... anyways. each of the 12 separate resistors connects one of 12 seprate pins on the RAM module to +3.3v. once again, from wikipedia:

A pull-up resistor is used in the design of electronic logic circuits. Pull-up resistors may be found at inputs to logic systems so that a definite logic level is asserted if an external device is disconnected. Pull-up resistors may also be used at the interface between two different types of logic devices, possibly operating at different power supply voltages.

so yeah. the actual data lines (all the lines that are not pulled up are either +3.3v or ground) are all pulled up, for whatever reason RDRAM needs the end of the bus to be pulled up. the jumper pack's main purpose is to provide these pullup resistors regardless of the third module being present.

so my point is you dont need to buy the parts. just use the ones in your jumper pack

Electric Rain · Post by **Electric Rain** » Mon Jan 02, 2006 6:58 pm

Good news bad news time.

Good news: I did some testing, and save for a few pins that seem to be NC and a few surface mount passives inbetween traces, it looks like every pin on the two 2MB chips are connected to eachother! (Pin 1 is connected to pin 1, pin 2 is connected to pin 2, ect.)

The bad news, is that I still don't actually know how the N64 detects the expansion pak. If EVERY pin truly is wired to the same pin on the same chip right next to it, (all signals wired in parallel) then the N64 has no way to detect single chips, which means that it says: "Okay, I see 8MB of RAM. They have an expansion pak." Hopefully this is the case. If it is, then my idea should work. However, if the chips each have a seperate pin that sets itself apart in the N64, then chances are it won't work. If this is the case, the N64 can probably sense each chip, meaning that my idea will make it say : "Alright, I see two 4MB chips, and... a jumper pak?

FRIED!" Anyone get what I mean?

timmeh87 · Post by **timmeh87** » Mon Jan 02, 2006 6:59 pm

as for pack detection, the jumper pack's pin number 2 is n/c. on the expansion pack, pin 1 and pin 2 are connected together. i suspect shorting pin 2 to ground is what indicates pack insertion.

Electric Rain · Post by **Electric Rain** » Mon Jan 02, 2006 7:02 pm

SWEET! If your theory is correct, then my idea should work if you short pin 2 to ground, and hardwire everything else like it was a jumper pak. This would essentially create a dumby expansion pak, right?

timmeh87 · Post by **timmeh87** » Mon Jan 02, 2006 7:03 pm

if you short it youd need the RAM module in there. ... if you DONT short it you just need the 12 pullup resistors and it should work.

Electric Rain · Post by **Electric Rain** » Mon Jan 02, 2006 7:07 pm

Yeah, but wouldn't I need to short it if I put two 4MB chips in place of the two 2MB chips, to make it look like there's an expansion pak in there?

timmeh87 · Post by **timmeh87** » Mon Jan 02, 2006 7:22 pm

it depends. it sounds like a pretty good idea. maybe theres something else required to tell the difference between 2x 2megs or one 4meg.

at this point i say you should just try it to see if it works.

but it will be pretty damn hard. i hope you know what you are doing. desoldering the RAM chips is difficult itself, and they are probably pretty sensitive to static. id avoid touching the leads at all costs, and wearing an anti-static wristband.

when you take them off, first remove all the solder from the back four pins of the module (i suggest copper braid. but if you can use a desoldering sucking thing if it works), carefully pry them off the board. then take allll of the solder that you can off the other 32 pins. use the tip of a thin razor blade to GENTLY tourqe the pins by gently prying inbetween them. most of them should break loose. if they dont right away, dont force it, desolder more. if there are a few left you can actually start torquing the whole chip while heating them. you can keep a few in a row hot at once with the edge of your iron.

anyways. thats how i take them off, ive done it about 3 times. it seems to work pretty well...

but id definitely practise on something garbage first. i did like 4 practise chips before i tried my first one.

Electric Rain · Post by **Electric Rain** » Mon Jan 02, 2006 7:47 pm

You're making me nervous.

Seriously though, thanks for the tips. Speaking of I'm actually going to need a new tip for my soldering iron before I even attempt this. And like you said, a desoldering braid.

I have a question for you, though. How many watts of heat were you using? I have a 30 watt iron, but I also have a stand for it with built-in wattage adjustment. I don't want to heat it up too much, after all.

timmeh87 · Post by **timmeh87** » Mon Jan 02, 2006 9:28 pm

i think mine is 30 watts. i dont know, i got it for 8 bucks at a Sayal. I keep the tip sticking more out of the iron and less into the iron, in an attempt to increase heat dissipation and decrease heat absorption of the tip. a temerature thingy like you have is definitely good.

anyhow, the chips can take a bit of heat. i think they can probably get up to like 80 degrees or so safely, maybe even under normal circumstances. granted, solder melts at almsot 300 degrees, so you still gotta pace yourself with the heating up of things.

Electric Rain · Post by **Electric Rain** » Tue Jan 03, 2006 2:03 am

Alright. I've got scans of the Jumper Pak and Expansion Pak boards (front and back).

Expansion Pak Front:

<Sorry, I know this one's a bit blurry...
Expansion Pak Back:

Jumper Pak Front:

Jumper Pak Back:

I'm not seeing where pins 1 and 2 are connected. Can you show me, timmeh87?