228-90095F
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7.1.3.3 Changing the gain of pre-amplifier (PB-1 ASSY)
If the light intensity is over the standard level after the optical system is adjusted,
lower the gain of the pre-amplifier by 7 % by the procedure described below.
＊ The lamp and optical elements (e.g. mirror, grating) of instruments where the
pre-amplifier has been modified may have to be replaced in several months to
several years depending on use frequency. In this case, the light intensity may
exceed the standard value due to a variation of the lamp or optical element
attached. However, no additional modification is necessary for instruments for
which the pre-amplifier has been modified once because there is enough
allowance in light intensity saturation voltage.
＊ If wax contained in soldering material remains on the surface of the board after
modification, it may cause poor insulation and eventually noise. If the board is
soiled, wipe it off with Kimwipe with a small amount of ethanol or IPA.
＊ Take out the PB-1 ASSY from the optical unit and modify the soldered face of the
PB-4 with an alignment of gain resistors mounted on the PB-1 ASSY using a
jumper wire* and solder as shown in the figure below.
* Recommended lead
wire
Conductor
cross-section area
Configuration Outer diameter
AWG #30 0.05 mm
2
7 pcs./0.102 mm 0.30 mm
[PB-1 ASSY Modification Drawing]
PB-1ASSY
Solder two positions on the soldered
face of PB-4 mounted on the PB-1
ASSY using an AWG30-level lead
wire and short-circuit it. (Left end of
R6:1 M and R7:2 M, both ends of
R23:1 M)
Enlarged soldered
face of PB-4
Optical unit
PB-4
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