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Troubleshooting

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Test 408.4 — Correction factor

Type

Circuit Exercise

Fault message

None

Description

This test is the same as test 408.3 except that no measurement is taken.

Drawing reference

Analog Board; 2002-100

Bit patterns

Test 408.5 — Signal stored for test 408.6

Type

Circuit Exercise

Fault message

None

Description

The SELFTEST control line turns ON Q425 and forces the voltage on NET1 (R488) to ground.

The response of R488 pin 4 is stored in C439. This test uses the same path as test 408.1 except

as follows: when the SELFTEST control line forces the divider voltage to zero, it also generates

a one-shot pulse 5µs after SELFTEST goes low. This pulse turns Q414 on and stores the voltage

on C439. The 5µs delay that controls U425 and Q414 is generated by U402. No measurement

is made during this phase.

Drawing reference

Analog Board; 2002-100

Bit patterns

Bit pattern* Register

—U400—

01111101

—U811—

00001101

—U224—

00010111

—U432—

00000000

—U810—

00000011

—U206—

01110000

—U203—

10001110

—U411—

00111011

—U809—

11100111

—U207—

11001111

—U221—

11101001

—U406—

01101110

AD_STB

MUX_STB

R1_STB

R2_STB

*Bits associated with register IC terminals as follows:

QQQQQQQQ

87654321 87654321 87654321 87654321

IC pins: Q8=11, Q7=12, Q6=13, Q5=14, Q4=7, Q3=6, Q2=5, Q1=4.