Memory for 2400c

The memory voltages used on the 'later' Powerbooks, such as the Wallstreet, and the earlier ones, the 2400 for example, are quite different. I'm pretty sure that they should be keyed differently and should have prevented you from installing it in the 2400.

Is the new RAM for the 2400 properly and fully seated in its slot? Did you try the Wallstreet memory before installing the proper memory? It might have fried the slot that you are trying to install it in.

Well it is a mystery, the 2400c uses an SODIMM slot that is similar to the Wallstreet, Lombard and Pismo. But after literally smoking that 32mb sodimm I have to figure the voltage isn't 3.3 v.

I wouldn't put it past Apple to have used a 5v chip in the 2400c since they first used 5v dimms in the 54/64/72/73/75/76/85/86/95/9600s as well as in the Power Computing clones I own. But I can't seem to find anything through Google to give me information as to what the exact difference between 2400c memory and the other SODIMMs really is.

The chip that is supposed to be for my PowerBook looks to have come from memoryten via welovemacs.com because of the memoryten sticker.

I guess at this point I have two conclusions, that the 2400c has a bad connector or defective MB or the chip is bad.

I tried the special chip before frying that 32mb one. I also tried a 64mb SODIMM from a Wallstreet after the correct one and that chip I just tested on a Wallstreet and it is fine. So could be that my 2400c is bad.

Oh well not the end of the world as I got the PowerBook with a good battery and QuickTake 200 camera for $78. It works fine but with only 16mb of real ram but I can't install 8.6 because the installer needs 24mb of real ram. Pity as I wanted to use an Aerolan card in it. Guess it'll live it's life teathered to a Global Village platinum card instead....

Kevin

Google for "Powerbook 2400c Developer Note". It'll tell you to look in the "Powerbook 3400 Developer Note" for the physical and electrical specifications. That in turn will tell you that those systems require 3.3v EDO RAM, whilst the "Wallstreet" and newer machines use 3.3v SDRAM.

The G3 developer note says that installing an EDO card will produce the "Chimes of Death", but doesn't say anything about it physically damaging the computer. The reverse may not be true, of course. (The 2400/2300 Developer notes say that while the slot conforms to the JEDEC physical specification it doesn't implement the SPD detection feature which informs the memory controller what sort of RAM you plugged in. So in principle it might be possible that "flying blind" the 2400c might enable the slot in some damaging configuration that the later G3 would avoid since it *does* use SPD.)

So... things pretty much boil down to this:

A: You had a "good" 2400c EDO DIMM, and your slot was already broken. You then just broke it a little more (shorted out the power leads, maybe), by plugging in that Wallstreet RAM. Said damage prevented you killing the *second* SDRAM DIMM.

B: You had a bad EDO DIMM, *then* fried your slot by plugging in the first (presumably good) SDRAM DIMM. That event killed it badly enough (like in A:) to prevent it from likewise frying the second Wallstreet DIMM. This is the scenario if plugging an SDRAM DIMM into a good 2400c *always* results in fireworks.

C: You had a bad EDO chip, which just didn't work, *and* a bad SDRAM chip which would of shorted out and blown up no matter what machine you plugged it into. This scenario applies if plugging an SDRAM chip into a 2400c doesn't *normally* result in fireworks. The two sub-scenarios here are:

1: Your slot is still okay, and might work if you got a *good* EDO DIMM. This depends on the "proper behavior" of a 2400 being that an SDRAM DIMM is just silently ignored (like the second one was), rather then producing errors. (chime of death, etc.)

2: You murdered the slot with the bad SDRAM, which prevented the second SDRAM from producing the chimes of death/errors/whatever.

Basically, there's one branch of this fault tree, item C1, which holds out hope that your machine would work if you found another 2400c RAM DIMM. If you can get one for cheap enough you don't have much to lose. Just don't bother anymore with newer SO-DIMMs from more modern machines. They definitely *won't work*, and plugging them in doesn't tell you anything.

--Peace

Thanks! Had not seen the Dev notes, only the information in service source which didn't say much other than how to take apart the PowerBook but no specifics on the memory.

Think I am at the point where I have to test the DIMM I got from welovemacs and see if it is bad although the chip I got has a different part number from the EDO dimm pictured on their website and just talked to someone there who says to submit an RMA request. Guess we'll see what happens. Darn and I passed on a 96mb chip for this the other day not realizing that these were that different!

Never got the chimes of doom or beeps that the Pismo lets out with bad memory, I have since tested a few other strips and either the PowerBook will not boot or will boot but not see the additional memory granted they are probably all SDRAM. I think I do have a couple EDO DIMMS floating around from a PC.

Have tried unplugging all batteries (pram and main) to see if that helps plus pram zapping. No joy, so looks like I have to find someone up here with a 2400c that is willing to test my memory or let me try theirs.

Thanks for your suggestions!

Kevin