How to upgrade your 505FX to 128MB

Considerations

But after my warranty was up, I decided to open up the machine and do some checks. First of all, the chipset is a 430TX, which supports up to 256MB maximum, and 128MB on machines with suspend to RAM support (it seems the second half is not being refreshed in sleep mode to save power). So, the chipset supports 128MB, next check was investigating the memory.

The mainboard had four Fujitsu MB811641642A-100LFN, each chip containing 4 banks of 16MBit. I then peeled of the warranty stickers of my Kingston 64 MByte expansion modules, revealing Hynix HY57V281620A chips (128Mbit, 8Mx16, Low Power, 100MHz, TSOP-II package), each chip containing 4 banks of 32MBit, and they were pin to pin compatible with the Fujitsu chips that were soldered to the 505FX's mainboard. I didn't see a reason why those chips shouldn't work in place of the original bank.

Brain Surgery

Getting the chips off the expansion modules was comparatively simple: I used a hot air gun that is normally used for shrink-wrap tubing. It took about ten seconds of heating the chips from the top before I was able to lift them off with a tweezer.

The hard part is getting the chips off the VAIO mainboard without ruining it or even just lifting off a trace. The hot air gun was out of the question, since it would blow off all parts surrounding the RAM chips as well. We have a surface mount infrared heating station at work, but that would heat the board from both sides, and I didn't trust that setup either. I ended up using another SMT rework station that we have, which heats up both rows of pins with a sort of tweezer/soldering iron. Add to that generous amounts of solder, and I could pop off three out of four chips easily. Oh, and the excess solder is easily removed with solder sucking wick as well. But the fourth chip was troublesome, the one nearest to the PCMCIA slot.

I was about to give up at that point, with my patient on the operating table and seemingly nearing cardiac arrest. The soldering tool seemed to heat up that plastic sheet that is between the PCMCIA slot and the board, and things started to smoke. But it was too late to go back, so I somehow managed to get that last chip removed as well.

Miraculously, all traces were still intact. After this, soldering in the "new" (recylced) chips was easy, although a microscope would have helped. I installed the spare 32MB expansion module I still had from the time I bought my VAIO, booted up, and........ 32MB total memory. In one bank. When I removed the bank, the machine wouldn't boot at all. Rats.

But there was hope. I had not shorted out any traces, or the machine would have been totally dead. So I concluded, that a trace must have been cut, or that I have a bad solder joint. I started with the latter possibility, and reworked some suspicious candidates, and after a few rounds of doing this (late at night, I might add), the machine powered up again with 96MB, only this time 64MB on the main board, and 32MB on expansion modules. You can see the result in the image to the right.

Epilog

The rest is, as you would probably call it, "history". I ordered another set of KSY505/64 modules (which I got for $40), installed the modules, and I now have 128MB in my good old 505FX. I even went so far as to see if the chips I brutally ripped off the mainboard would still work on the expansion modules, and lo and behold: they still work. Actually, if you take a close look at the picture of the modules at the top, you'll see they are the Fujitsu chips I took out of my VAIO.

Of course, you don't have to buy expansion modules for this purpose; if you happen to find compatible SDRAM chips on some old module, you can try those. But since the expansion modules are cheap these days, and guaranteed to be the low power versions in low profile packages, I'd go for those.

Please note that this article is for informational purposes only! If you want to ruin your VAIO, out of all the modifications presented on these pages, this is the best and easiest way to do it. But if you're daring, have experience with surface mount parts, or are just plain desparate to max out your 505FX (and probably 505G, 505GX, 505F as well), at least now you know it's possible. If you want to try and see if this modification works on your VAIO too is up to you and your own risk...

Save to Disk partition

After you have upgraded to memory to 128MB, you may want to increase your save to disk partition. The utility to do this is phdisk, a Phoenix BIOS utility for setting up a save to disk partition. In my case, phdisk complained though that there is insufficient space on the drive. And since (if you have a bigger drive) the STD partition needs to be in the first 8G the BIOS can address, I had to resize my partitions. I'm sure you can use Partition Magic for this, but I don't have it. I use Ghost for backup anyway, so I use it to resize my partitions too:

In order to do this, first, make a boot disk. Plain DOS, and put fdisk and phdisk on there. Try if it boots. Then Ghost your partition(s) patiently to a safe medium. Now comes the scary, "no way back" part. Use fdisk to delete any and all partitions you have. After fdisk shows "no partitions", start phdisk /delete /partition to delete any existing STD partition, then phdisk /create /partition to set up a new partition. After the computer has rebooted, go to fdisk again, verify there is a STD partition existent now, and repartition the rest of the drive to your needs, and Ghost your old partition data back on the drive.

Compatible RAMs

According to Winbond, the following RAMs are compatible with the Hynix RAM on the Kingston memory modules:

• Samsung K4S281632B/C
• Micron MT48LC8M16A2TG
• Toshiba TC59SM716FT/AFT
• Elpida uPD45128163
• Infineon HYB39S128160CT(L)
• Winbond W981216BH

Maybe you're in luck and you find four of these chips in another old SDRAM module, and use those instead. Whatever you do, you do it on your own risk...

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