
TM 9-4935-601-14-7&P
Model 8640B
CHANGE 32 (Cont'd)
Page 6-26, Table 6-3:
Change AllR28 to 2100-2574 RESISTOR; VAR; TRMR; 500 OHM 10% C.
Service Sheet 9A (schematic):
Delete asterisk (*) at AllR28 and change the symbol to a 5002 potentiometer whose wiper is connected to the
junction of AllR28 and All1RT1.
CHANGE 33
Page 6-22, Table 6-3:
Delete A10A2R38 and R39.
Page 6-34, Table 6-3(see Change 13):
Change A26A1R21 to 0698-7233 RESISTOR, FXD, 750 OHM 2% 0.05W F TC=0+100.
Change A26A1R22 to 0698-7272 RESISTOR, FXD, 31.6K 2% 0.05W F TC=0O100.
Service Sheet 11 (schematic):
Delete resistors A10A2R38 and R39.
Service Sheet 19 (schematic):
Make the following changes to the A8A3 assembly.
Change R10 and R17 to 1960 ohms.
Change part numbers for U10, U11, U16 and U17 to 1820-1490.
Change part numbers for U13, U14 and U15 to 1820-1429.
NOTE
In instruments with serial number prefix 1545A or below, if A8A3U16 or U17 is replaced with 1820-
1490, the respective pull-up resistor A8A3R10 or R17 must also be updated to the recommended
new value, 1.96K.
CHANGE 34
Page 6-13 through 6-15, Table 6-3:
Change A8A2C4 to 0180-0374, CAPACITOR, FXD 10OUF ± 10% 20WVDC
Change A8A2C12 to 0160-2207, CAPACITOR, FXD 300PF ± 5% 300 WVDC
Add A8A2C32, 0180-0374, CAPACITOR, FXD 10OUF ± 10% 20WVDC
7-75
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