Lake Shore 625, User Manual

Page: 109 / 132

Lake Shore Model 625 Superconducting MPS User’s Manual
Service 7-7
7.10 FIRMWARE REPLACEMENT
There are two integrated circuits (IC) that may potentially require replacement. See Figure 7-3 for the IC location.
• Main Firmware Erasable Programmable Read Only Memory (EPROM) (U22) – Contains the user interface software.
Has a sticker on top labeled “M625F.HEX” and a date.
• DAC Microcontroller (U43) – Contains software that controls the output DAC’s. Has a sticker on top labeled
“M625DACF.HEX” and a date.
Use the following procedure to replace either of these ICs.
1. Follow the top of enclosure REMOVAL procedure in Paragraph 7.9.
2. Locate the IC on the main circuit board. See Figure 7-3. Note orientation of existing IC.
CAUTION: The ICs are Electrostatic Discharge Sensitive (ESDS) devices. Wear shock-proof wrist straps
(resistor limited to <5 mA) to prevent injury to service personnel and to avoid inducing an
Electrostatic Discharge (ESD) into the device.
3. Use IC puller to remove existing IC from the socket.
4. Noting orientation of new IC, use an IC insertion tool to place new device into socket.
Eprom.eps
5. Follow the top of enclosure INSTALLATION procedure in Paragraph 7.9.
7.11 PSH OUTPUT COMPLIANCE VOLTAGE CONFIGURATION
The persistent switch heater output maximum compliance voltage is configurable for 15 V or 24 V operation. This is
configured by changing an internal jumper. The default setting is for 24 V operation. The actual voltage compliance limit
is dependant on load but guaranteed to be at least 12 V or 21 V depending on the setting. Use the following procedures to
change the PSH output maximum compliance voltage:
1. Follow the top of enclosure REMOVAL procedure in Paragraph 7.9.
2. Locate the jumper (JMP 2) on the main circuit board. See Figure 7-3.
3. Place the jumper on the correct compliance voltage setting. The settings are printed on the circuit board.
4. Follow the top of enclosure INSTALLATION procedure in Paragraph 7.9.