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EEPROM lock instructions 

All parts and tools are available at your local Radio Shack 

Parts Needed: 

1. Switch, Single Pole Double Throw (SPDT) 
2. Resistor, 1K-Ohm Watt 
3. Wire, Wire Wrap type wire preferred 

Tools Needed: 

1. Soldering Iron, (NOT a soldering GUN) 
2. Pencil type 30-45 Watts 
3. Solder, Rosin Core, .062" diameter or smaller, 
4. 60/40 Tin-Lead mix Soldering Aids, 
5. Pick type tool to lift pin

switch wiring.jpg (18372 bytes) Switch Wiring Instuctions

 

EEPROM Pin Out Diagram: 


Referring to the graphic below, the "Asterisk" denotes pin-1 on all DIP (Dual Inline Package) styled chips. Some chips may have a "dimple" while others may only have the "U". The pin to the LEFT of the "U" IS pin-1, in case your EEPROM chip does not have the "dimple". 

The pin out on the EEPROM is as follows: 

1--|*-U-|--8 
2--|-----|--7 
3--|-----|--6 
4--|-----|--5 


Wiring Procedure: 


1. Drill a hole in the back of the IRD frame, and mount the SPDT switch so that the legs/pins on the switch are lining up in a vertical manner. 

2. Locate the serial EEPROM. This IC is an 8-pin chip usually surface mounted, and most are a Microchip 24LC16B. 

3. Lift pin-7. To do so heat the pad and use a dental pick tool to gently lift the pin from the copper land. 

4. Solder a wire from the lifted pin-7 on the IC to the center pin of a SPDT type switch. 

5. Solder a wire from pin-4 (Vss or Ground) to the bottom pole of the switch. 
(Do not use the pad from pin-7 since the space between the lifted pin-7 and the pad is so small, that doing so can cause short). 

6. Solder a 1K-Ohm Watt resistor to the remaining leg on the switch. 

7. Lastly solder a wire from pin-8 of the EEPROM to the free leg on the 1K Ohm 1/4 Watt resistor. 

With this modification controlling the EEPROM is now that much easier. 

Switch Settings: 

To UNLOCK the EEPROM, flip the switch lever so that it points UP. 

To LOCK the EEPROM flip the switch lever so that it points DOWN. 

eeprom.jpg (19994 bytes)   Eeprom Picture

eeprom lock.jpg (12302 bytes)   Wiring Instructions

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