Lake Shore Model 475 Gaussmeter User’s Manual
Service
8-3
Fuse Replacement (Continued)
NOTE:
Test fuse with an ohmmeter. Do not rely on visual inspection of fuse.
1. Locate line input assembly on the instrument rear panel. See Figure 8-2.
2. Turn power switch Off (
O
).
3. Remove instrument power cord.
4. With a small screwdriver, release the drawer holding the line voltage selector and fuses.
5. Remove and discard both existing fuses. Replace with proper Slow-Blow (time-delay) fuse ratings as follows:
100/120V 0.5A
5
×
20 mm T
220/240V 0.25A 5
×
20 mm T
6. Re-assemble line input assembly in reverse order.
7. Verify voltage indicator in the line input assembly window.
8. Connect instrument power cord.
9. Turn power switch On (
l
).
8.6
ERROR MESSAGES
The following messages appear on the instrument display when it identifies a problem during operation. The messages
are divided into three groups. Instrument hardware messages are related to the instruments internal circuits or non-
volatile memory. If one of these messages persists after power is cycled the instrument requires repair or recalibration.
Measurement messages are most often associated with over field conditions caused by an improperly selected field range
or excessive noise on the measurement leads, or a missing or illegal probe. If these messages persist after proper
configuration, the instrument may require repair. Illegal operation messages remind the operator when a feature is
locked out or the instrument is not configured to support a feature.
Instrument Hardware
Defective RAM
Internal RAM is defective and must be replaced
Invalid EEPROM
EEPROM contents are corrupt and parameter values will be reset to default.
Reoccurrence may indicate defective EEPROM. Calibration may be affected.
Input Not Responding
Internal processor communication has failed.
Invalid Calibration
Instrument has not been calibrated or calibration memory has been corrupted.
Recalibration is required for accurate measurements. Press the Escape and Enter keys
simultaneously to clear the message. The instrument can still be used but it may not be
operating within specifications.
Measurement
No Probe
There is no probe attached or the attached probe is damaged.
Invalid Probe
The detected probe is not recognized as a valid Model 475 probe. Press Enter to
continue.
Incompatible Probe
A previous generation probe has been attached. Press Enter to continue. Measurement
uses only nominal probe sensitivity. Accuracy not guaranteed.
OL
The measured field is larger than the range. Increase the measurement range.
Check probe zero.
SUNDER
The temperature sensor reading is less than the minimum temperature table entry.
SOVER
The temperature sensor reading is greater than the maximum temperature table entry.
Illegal Operation
*LOCKED*
A key operation was attempted with the keypad locked.
Not Available During
Field Control
Certain operations are not allowed during Field Control.
Max Not Available
With Peak
Max Hold and Peak do not operate together.
Invalid MPEC Cable
Improper cable attached during the MPEC programming process.
Invalid MCBL Cable
Improper cable attached during the MCBL programming process.
