Analog Circuitry Checks; Battery Replacement; Battery Replacement Precautions - Keithley SourceMeter 3A 2420 Service Manual

4-12 Troubleshooting

Analog circuitry checks

Table 4-4 summarizes analog circuitry checks.
Table 4-4

Analog circuitry checks

Step
1
2
3
4
5
6
7
8
9
*Measured with respect to FCOM (TP500).
**Measured with respect to OCOM (TP501).

Battery replacement

WARNING
The volatile memories of the Model 2420 are protected by a replaceable battery when power is
off. Typical battery life is approximately 10 years. The battery should be suspected if the instru-
ment no longer retains buffer data or user-defined operating parameters such as instrument setups,
source memory, and math expressions. If the battery is absent or totally exhausted, the display will
show the "Reading buffer data lost" message shortly after the Model 2420 is switched on.
The battery is a 3V wafer-type lithium cell, Panasonic type BR-2330 or equivalent (Keithley
part number BA-46), which is located on the digital board. Replacement of the battery requires
removal of the case cover and analog board assembly. (See Section 5.)

Battery replacement precautions

WARNING
WARNING
Item/component
TP200* >60V voltage protection
TP201* SOURCE +10V
TP202* SOURCE +10V (SVMI)
TP203* SOURCE +10V
TP213* SOURCE +10V
TP218** OUTPUT COM
TP219** OUTPUT COM
TP214** SVMI, OUTPUT ON, 20V
TP232* Bench defaults
Disconnect the instrument from the power line and all other equipment
before changing the battery.
There is a danger of explosion if battery is incorrectly replaced. Replace
only with the same or equivalent type recommended by the manufacturer.
Dispose of used batteries according to federal, state, and local laws.
The precautions below must be followed to avoid personal injury.
• Wear safety glasses or goggles when working with lithium batteries.
• Do not short the battery terminals together.
• Keep lithium batteries away from all liquids.
• Do not attempt to recharge lithium batteries.
• Observe proper polarity when inserting the battery in its holder.
• Do not incinerate or otherwise expose the battery to excessive heat (>60°C).
• Bulk quantities of lithium batteries should be disposed of as a hazardous
waste.
Required condition Remarks
-13V ±1V
-5V ±0.5V
-10V ±1V
-10.5V ±1V
0V ±0.1V
7V ±0.7V
7V ±0.7V
20V ±0.5V
6.4V ±0.6V