Lake Shore Model 421 User Manual
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Lake Shore Model 421 Gaussmeter User’s ManualService 6-76.6 TOP OF ENCLOSURE REMOVAL AND REPLACEMENTWARNING: To avoid potentially lethal shocks, turn off gaussmeter and disconnect it fromAC power line before performing this procedure. Only qualified personnelshould perform this procedure.6.6.1 Removal Procedure1. Turn power switch Off (O).2. Remove instrument power cord.3. If attached, remove rack mounting brackets.4. Use 5/64 hex key to remove four screws attaching top panel to unit.5. Use 5/64 hex key to loosen two rear screws attaching bottom panel to unit.6. Carefully remove the back bezel by sliding it straight back away from the unit.7. Slide the top panel back and remove it from the unit.6.6.2 Installation Procedure1. Slide the top panel forward in the track provided on each side of the unit.2. Carefully replace the back bezel by sliding it straight into the unit.3. Use 5/64 hex key to install four screws attaching top panel to unit.4. Use 5/64 hex key to tighten two rear screws attaching bottom panel to unit.5. If required, reattach rack mounting brackets.6. Attach instrument power cord.7. Turn power switch On (l).6.7 EPROM REPLACEMENTThe operating software for the Model 421 is contained on one Erasable Programmable Read OnlyMemory (EPROM) Integrated Circuit (IC). The reference designator for the EPROM is U36, Lake ShorePart Number 113-591. The EPROM has a sticker on top labeled with “M421.HEX” and the date. Usethe following procedure to replace the EPROM.CAUTION: The EPROM is an Electrostatic Discharge Sensitive (ESDS) device. Wear shock-proofwrist straps (with a resistor that limits current to <5 mA) to prevent injury to servicepersonnel and to avoid inducing an Electrostatic Discharge (ESD) into the device. Refer toParagraph 6.2.1. Follow the top of enclosure REMOVAL procedure in Paragraph 6.6.1.2. Remove four phillips-head screws attaching transformer bracket to the Model 421 chassis.Carefully pull transformer bracket up and sufficiently out of the way to gain access to theOperating Software EPROM. See Figure 6-6.3. Locate EPROM U36 (M421.HEX) on the main circuit board. Note orientation of existing IC.=>?>??@% * ='9-*+ *+='9- *+ 1 *Aeprom.eps4. Use IC puller to remove existing EPROM from socket.5. Noting orientation of new EPROM, use an IC insertion tool to place new device into socket.6. Install four phillips-head screws attaching transformer bracket to the Model 421 chassis.7. Follow the top of enclosure INSTALLATION procedure in Paragraph 6.6.2. |
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