Modifying Version F or Earlier PCB's for use with V5.00 Software

V5.00 Software requires that a 93C66 EEPROM is used for non-volatile storage. Version G and later PCB's are fully compatible with 93C66 EEPROM's, however, earlier PCB's require a slight modification to allow them to be used to their full capacity. See What happens if you don't do this mod.

How do I tell which version of PCB that I have?

On the top side of the PCB, look for the designation SD000101x or MD2002x. The "x" is the version number.

Making the modification

The EEPROM is the 8 pin Dual Inline Package chip in roughly the middle of the PCB. To modify it, go to the bottom side of the PCB and locate pins 5 through 8 (on the opposite side from Pin 1, which is marked as a square pad). See Photo 1 below to get an idea about the modification.

Pin 7 needs to be isolated from Pins 6 and 8 and then re-connected to pin 5. Do the following:

cut the link from pin 7 to pin 8 using an Exacto knife, or equivalent.
cut the link from pin 7 to pin 6
add a short wire from pin 7 to pin 5 (requires skill with soldering). It is best to do this on the bottom side of the PCB.

In some older versions of PCB's, additional cuts and wires need to be made. Photo 1 shows all the mods.

cut the link from pin 7 to the square pad of the adjacent capacitor
add a wire from pin 8 to the square pad of the capacitor
add a wire from pin 8 to pin 6

What happens if you don't do this mod?

you cannot achieve the maximum 60 sensors. The limit will be 30.

Picture - bottom of PCB showing location of EEPROM

Photo 1. Bottom view of PCB showing location of cuts and strap

(photo courtesy of Malcolm Surgenor)