
Troubleshooting
2-50
Bit patterns
Test 300.3 — A/D MUX 0V reference, X50 A/D MUX gain
Type
Pass/Fail
Fault message
A/D MUX 0V ref., x50 gain
Description
U222 is set up to switch common through R259 and S1 pin 4 input to the A/D buffer U226. U226
is set up for X50 gain through U227 pin 15 to 14 with /X50 pin 16 low. R286 provides the feed-
back for U226 X50 gain. Also, common is switched through R312 and U242 pins 2 to 3, through
R311 and to pin 3 of U253. U253 is the buffer for ADGND. ADGND is routed to A/D_IN
through the parallel combination of R285 and R286. Common is the input to A/D_IN. Common
is switched through R259 and U222 pin 4 to pin 3 of U226.
Drawing reference
Analog Board; 2002-100
Components
U222, U226, U227, U253, and associated components.
Bit patterns
Bit pattern*
Register
—U400—
01111011
—U811—
00001101
—U224—
00010111
—U432—
10000000
—U810—
00000011
—U206—
10110000
—U203—
10001110
—U411—
11111011
—U809—
11100111
—U207—
01010111
—U221—
11101001
—U406—
00000100
AD_STB
MUX_STB
R1_STB
R2_STB
*Bits associated with register IC terminals as follows:
Q
Q
Q
Q
Q
Q
Q
Q
87654321
87654321
87654321
87654321
IC pins: Q8=11, Q7=12, Q6=13, Q5=14, Q4=7, Q3=6, Q2=5, Q1=4.
Bit pattern*
Register
—U400—
01111011
—U811—
00001101
—U224—
00010111
—U432—
10000000
—U810—
00000011
—U206—
11010000
—U203—
10001110
—U411—
11111011
—U809—
11100111
—U207—
00001111
—U221—
11101001
—U406—
00000100
AD_STB
MUX_STB
R1_STB
R2_STB
*Bits associated with register IC terminals as follows:
Q
Q
Q
Q
Q
Q
Q
Q
87654321
87654321
87654321
87654321
IC pins: Q8=11, Q7=12, Q6=13, Q5=14, Q4=7, Q3=6, Q2=5, Q1=4.
Содержание 2002
Страница 1: ...Model 2002 Multimeter Repair Manual Contains Servicing Information...
Страница 125: ...Troubleshooting 2 112...
Страница 145: ...A Specifications A 1...