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Making Standard SIMM s Work / Memory Upgrade on the HP LaserJet 6MP / 5M

***I am not responsible for your ruining your perfectly good and <sarcasm>highly valuable</sarcasm>

72 pin SIMMs or your HP LaserJet printer. Proceed with CAUTION and NOTE: This procedure worked on

my 6MP and MAY NOT WORK FOR YOU AND COULD DAMAGE YOUR EQUIPMENT. Read these instructions

in entirety before beginning work.***

Overview

I am a bit of a computer and electronics junkie and recently had the opportunity to purchase a close to new HP LaserJet 6MP at auction for next to nothing. Being the curious chap that I am, I wondered how much RAM the thing had and if I could possibly upgrade it cheaply (ie: not have to buy the HP-approved upgrade modules). I found that the unit had the standard 3 Megabytes installed and that it also sports two empty 72 pin SIMM slots, much like those found on older 486 motherboards. This really peaked my interest because I have a bag of totally worthless SIMMs laying around that I figured I could use. After doing a little research, I found that:

•The following HP LaserJet printers seem to use the same type of RAM: 5, 5M, C3100A, 6MP, 5Si MOPIER, 5Si

MX, 5Si, 5Si NX, 5M, 5, 5N, 5se, 4+, 6P, 6Pxi, 6Pse, 5P, 5MP, 4MV, 4P, 4MP, DesignJet: 750C, 750C Plus,

700, 330, 350C, DeskJet: 1600CM, 1600C, 1600CN, PaintJet XL300

•Depending on your printer, you may have a different maximum capacity. The memory capacity on the 6MP is 35 Megs (Two 16 MB sticks + PostScript card RAM + Internal RAM).

•HP used a technology called “presence detection” that essentially jumpers unused pins on SIMM memory modules together in certain sequences to tell the printer how much RAM is installed and what type it is.

•Any 72 pin RAM SIMM can be used on the 6MP so long as it is 70ns or slower speed and is equipped with “presence detection” or jumpered pins.

*Most of this information I obtained from a newsgroup posting titled “SIMM Identification for LaserJets”, Author Unknown and eBay auctions for SIMM modules for the HP printers.

Being that I had a whole bag of RAM that I could sacrifice and some free time on a boring Sunday afternoon, I decided to try to make my SIMMS work in my 6MP LaserJet printer. The first attempts worked on a 4 meg SIMM, but I wanted to max out the RAM, so I perfected my technique on a second set of RAM. This process is detailed below.

Required Supplies & Tools

You will need a few tools to operate on your RAM and make it compatible with your LaserJet, DesignJet, DeskJet, or PaintJet printer. They are pictured below (click the picture to enlarge in a popup):

The needed tools are:

•15 watt (or lower) soldering iron - too hot an iron will burn your memory componets

•Multimeter - digital or analog doesn’t matter so long as you can detect continuity (use the OHM setting)

•Stranded wire to use for jumpers (one strand per jumper) - speaker wire works well

•Needle-nosed pliers help hold the hot wire while you solder

•Solder wire, of course

•Wire cutters

•Grounding strap (optional, but highly recommended) to discharge static electricity

12/14/2003