93C46 Connections


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Safety Precautions to ensure that your KeyMaker Board and ThinkPad are not damaged

In order to avoid damage to your KeyMaker Board as well as the ThinkPad you are using it on, there are certain precautions you MUST observe.

If you ignore these precautions you will join the 3% of customers who bought a KeyMaker board - ignored these precautions and damaged their KeyMaker Board  by being careless - then had to pay to have it replaced - and lost a lot of time in the process.

Your KeyMaker has electrical contacts on both sides, you must ensure that no part of your KeyMaker USB board comes into contact with any conductive surfaces such as bare metal or bare wires.

You should place down a piece of paper and place your KeyMaker USB on top of it in order to avoid any electrical contact which may damage your KeyMaker.

There is no danger of receiving an electrical shock from your KeyMaker USB as the highest voltage anywhere on the board is 5 Volts which is a safe voltage to touch.

If you prefer you can place your KeyMaker USB board inside an Anti-Static  plastic bag during use, the board does not get warm at all, so there is no issue with ventilation.

The same precautions apply to your ThinkPad when you are performing any operation and BEFORE your ThinkPad is switched ON, you must ensure that nothing can short out by coming into contact with other parts, you can use sheets of plastic or plain paper to make sure things remain electrically isolated.

You MUST NOT allow the SDA and SCL leads from any KeyMaker KMX1 or KMX2 to come into contact with ANYTHING other than the correct SDA and SDA EEPROM connections points and ONLY AFTER;

You have traced the wire you are using for your probe right back to the label on the I2C header on the KeyMaker board which reads SDA for YOUR SDA lead and reads SCL for YOUR SCL lead.

You have absolutely confirmed that you have correctly identified the SDA and SCL connection points on your ThinkPad System Board.

3% of customers who purchased a KeyMaker Board have somehow managed to damaged their KeyMaker board.

NOT ONE of those customers can tell me exactly what he or she did to damage it.

I have tried all sorts of seriously ridiculous ways to damage a KeyMaker board and I have NOT BEEN ABLE TO DAMAGE ONE !

I only tried MILDLY STUPID THINGS like connecting a solid 9 Volt source to SDA and SCL - theoretically that should have damaged the I/O pin on that KeyMaker powered from 3.3 Volts, IT DIDN'T.

Your KeyMaker board is a delicate piece of equipment, treat it with respect.

Do NOT experiment or connect to anything if you are not certain you have the correct connection points identified.

There are voltages much higher than 3.3 Volts inside your ThinkPad, in fact up to 20 Volts. 

20 Volts is not a danger to YOU but it is to the KeyMaker KMX1 or KMX2.

Connect SDA and SCL leads ONLY if you have double checked and are CERTAIN you have correctly identified SDA and SCL connection points

The above is VERY IMPORTANT - don't ignore it else you WILL damage your KeyMaker KMX1 or KMX2 board and that is expensive, wastes a lot of time and is not much fun.

Read more on Safety Precautions here

Most people can simply ignore the 93C46 EEPROM, it is only found in a few really old TP models

The most common EEPROMS used to store passwords in TPs are LSI, 24RF08, 24C01 and very rarely 24C03. These EEPROMS can be read without unsoldering them from the system board and normally require only 3 connections GND, SCL and SDA.

Those 3 connections points are clearly labelled on the KMX1 Board (white silk screen writing on the board)

The 93C46 EEPROM is very different, it needs 6 connections and it MUST be unsoldered from the board in order to recover the password stored in it. 

ONLY unsolder a 93C46 if you have;

  1. The right Surface Mount Device (SMD) unsoldering/soldering tools

  2. You have experience at using those tools properly.

If in any doubt about about your ability to unsolder a SMD 93C46 - I suggest you don't do it, rather have someone else who does this for a living do it for you.

If you cheerfully go ahead and you don't know what you are doing and lack the tools and skills required, you will simply ruin the System Board and EEPROM

The following information is for those possessing the right tools and skills.

KMX1 connection point to an unsoldered 93C46


I make no warranty that any of my information is correct, or safe, or does or does not breach any warranty clause,  or anything else, it is up to you to decide if you will follow all or any of the instructions to recover the Supervisor Password from a TP. It is up to you to decide, I am not responsible for the results or for any consequential or incidental damages whatsoever.

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If you have any questions, email Joe at

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