Log Amp Board Adjustment; Sw1/Sw2 Settings And Corresponding Trimmers - Hitachi 902 Service Manual

14.1.2 LOG AMP Board Adjustment

Adjust the LOG AMP board at the rear of instrument in the procedure below. The standard
lamp should be used for this.
< Adjusting procedure >
(1) After turning on the instrument, wait for at least 30 minutes (for the lamp to stabilize).
(2) Make sure there is water in the reaction bath, and carry out the following adjustments.
Check if voltage is 2.00 ± 0.005 V across check pins TP20-TP15 (G). If not, adjust it with
(3)
trimmer VR14.
Check if voltage is 6.00 ± 0.005 V across check pins TP21-TP15 (G). If not, adjust it with
(4)
trimmer VR13.
Flip toggle switch SW3 upward, and adjust trimmers VR1 to VR12 to obtain 1.81 ± 0.05 V
(5)
across check pins TP14-TP15 (G) at positions 0 to B of rotary code switch SW1.
Table 14-2 shows the settings of rotary code switches SW1 and SW2 and the trimmers to
be used for adjustment.
(6) When adjustment with trimmers is finished, set rotary switches SW1 and SW2 to "F" and
flip the toggle switch SW3 downward.
Table 14-2 SW1/SW2 Settings and Corresponding Trimmers
Wavelength No.
1
2
3
4
5
6
7
8
9
10
11
12
SW1 Setting
0
1
2
3
4
5
6
7
8
9
A
B
14 - 2
SW2 Setting
0
1
2
3
4
5
6
7
8
9
A
B
Adjusting Trimmer
VR1
VR2
VR3
VR4
VR5
VR6
VR7
VR8
VR9
VR10
VR11
VR12