This page outlines selected excerpts from the Perkin-Elmer Coleman Model 6|20 and 6|35 JuniorŪ II Spectrophotometer User's Manual (CP99423). These units are used in various spectroscopy labs at Niagara College.


1.01 This manual contains all operating instructions and associated information for JuniorŪ II Spectrophotometers, Models 6120 and 6135. All of the many cuvettes and adapters used with previous models in the Junior series are usable with the Junior II instruments. Operating capabilities are provided in table 1-1 along with other pertinent information.

Table 1-1. Technical Data

  1. Wavelength
    325 to 825 nanometers (nm) (also; millimicrons, mu)
  2. Wavelength Calibration
    Model 6|35: +/-1 nm at 585 nm
    Model 6|20: +/-1 nm at 585 nm
  3. Bandpass
    Model 6|35: 35 nm (nominal)
    Model 6|20: 20 nm (nominal)
  4. Wavelength Reproducibility
    +/- 0.5 nm, or less at each minor division
  5. Photometric Reproducibility
    0.5% Transmittance
  6. Photometric Readability
    0.2% Transmittance on an 8-inch Transmittance (T)-Absorbance (A) scale
  7. Recorder Output
    20 millivolts (mv) open circuit. 30,000 ohms output impedance. Designed for use with l0-mV recorders having an input impedance of 50,000 ohms or more
  8. Power Requirements
    110 or 220 volts (95 to 135 volts, or 190 to 270 volts) 50 to 60 cycles single phase ac, 140 watts
  9. Input Limits (Overload)
    40 volts input voltage level referred to ground 10 volts maximum signal voltage across input
  10. Output Available (as amplifier)
    125 millivolts maximum
  11. Cuvette Well
    Accepts cuvettes and other items as described in price list (end pages)

Patent Notice: This Instrument is covered by U. S. Patents 3,407,869 and 209,823. Other U. S. and foreign patents issued and pending.



3.01 All controls, indicators, and other operational items are described in table 3-1. Refer to fig. 3-1 and fig. 3-2 as necessary and become thoroughly familiar with the function of each item before operating the instrument for the first time.

Table 3-1. Controls and Operational Items

Item Function
Line Power ON-OFF Switch This is the power ON-OFF switch, controlling all power to the instrument
Scale Panel Provides transmittance scale (black) and absorbance scale (red). Transmittance is calibrated from 0% to 100% and absorbance is calibrated from 2.0 to 0. The scale panel is movable for fine zero adjustment and is removable and replaceable with other scale panels (par 2.08)
Wavelength Control Continuously variable control. Used to set monochromator within the range from 325 nm to 825 nm. Locks lamp arm at 825 nm stop

NOTE: Do not continue to turn knob after reaching either extreme of knob travel as this will cause undue wear on the drive system.
Wavelength Dial Indicates wavelength setting of monochromator as set by wavelength control. A change in background color indicates a change in filter required. See filter selector control in this table.
COARSE Control A continuously variable control used for coarse setting of instrument response level. Used when instrument is adjusted with a reference or blank. Eight index marks, alternately numbered 1, 3, 5 and 7, are provided for convenience in recording or repeating settings
FINE Control This is a continuously variable control used for fine adjustment of instrument response level after adjusting instrument with COARSE control
Filter Selector A three-position selector switch providing the following functions:

UV - Positions UV stray light filter for 325 to 380 nm operation corresponding to blue area on wavelength dial

VIS - Positions VIS stray light filter for 380 to 650 nm operation corresponding to white area on wavelength dial

NIR - Positions red stray light filter for 650 to 825 nm operation corresponding to red area on wavelength dial. Also, eliminates the second order spectrum

ZERO Lever Control A continuously variable control used for coarse setting of galvanometer mechanical zero position. Control lever located in recess under front panel.
INPUT Jack Acecpts 0.140-inch diameter miniature phone plug (Telex PM.01 or equivalent). Photocell automatically disconnected when plug is inserted.
RECORDER 10mV Receptacle A two-pin polarized receptacle used to connect instrument output signal to recorders or other equipment. Accepts a Jones P302 or equivalent plug.
Cuvette Well Accepts cuvettes and adapter-cuvette combinations containing sample or reference material and various accessories.


Do not place dust cover on instrument until certain line power ON-OFF switch (fig. 3-2) is in the OFF position.

Do not permit objects, especially metallic objects, to drop through the slots on the grill at the top part of the rear door heat sink (fig. 3.2) as they might ground the heat sink and damage the instrument. Turn instrument OFF and unplug line cord before removing such objects.

Do not obstruct the grill (fig. 3-2) at the top rear of the instrument at any time during operation.

Do not short the heat sink casting, exciter lamp or any connections to the instrument case, or the chassis (fig. 5-1).


3.03 Before using the instrument for the first time and subsequently as experience dictates or precision demands, verify and adjust instrument calibration according to the following procedures.



3.04 Before operating the instrument for the first time, it is suggested that the analyst be familiar with handling cuvettes and with other aspects of the analysis (Section III). The procedure below provides complete start-to-shutdown instructions. It is assumed that the desired scale panel is in position and that the instrument is properly installed, adjusted and calibrated. Accomplish the procedure in the order presented to secure best analytical results.