Jenway 6400, 6405 Service manual
Jenway 6400/05
Spectrophotometer Service Manual
Section 1 Introduction
Section 2 Quick Reference
Section 3 System Description
Section 4 Optical Description
Section 5 Electronic Description
Section 6 Software Description
Section 7 Diagnostics
Section 8 Maintenance
Section 9 Circuit Diagrams
Section 10 Assembly Diagrams
Section 11 Spare Parts List
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Section 1
Introduction
1.0 Index to Sections
1.1 About This Manual
1.2 Using This Manual
1.3 Warnings & Safe Practice
1.4 Standards & Certification
1.5 Ordering Spares
1.6 Returning Items
1.7 Contacting Jenway Limited
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Introduction.
1.0 Index to Sections
Section 1 – Introduction
1.0 Index to Sections
1.1
1.2
1.3
1.4
1.5
1.6
1.7
About This Manual
Using This Manual
Warnings & Safe Practice
Standards & Certification
Ordering Spares
Returning Items
Contacting Jenway Limited
Section 2 - Quick Reference
2.0 About ‘Quick Reference’
2.1
2.2
2.3
2.4
2.5
2.6
2.7 Test Solutions
Specification
Main Sub-Assemblies
Power Supply Voltages
Signal Levels
Error Codes
Special Key Functions
Section 3 - System Description
3.1
3.2
3.3
3.4
6400 & 6405 Comparison
Sub-Assemblies
Accessories
Outputs
Section 4 - Optical Description
4.1
4.2
4.3
4.4
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Light sources
Stray Light Filters
Grating
Signal Detector
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Section 5 - Electronic Description
5.1
5.2
5.3
5.4
5.5
Power Supplies
Deuterium Lamp Supplies
Detector Circuit
Microprocessor and Memory Functions
Accessory driver PCB
Section 6 - Software Description
6.0 Warning
6.1
6.2
6.3
Start Up Routine
Main Menu
Menu Options
Section 7 – Diagnostics
7.1
7.2
7.3
7.4
7.5
7.6
7.7
7.8
7.9
The Diagnostics Menu
Shutter and Filters
Lamp Control
Zero Order Cal.
Calibrate Functions
Wavelength Functions
Channel Outputs
Voltage Display
Motor Position sensor
Section 8 – Maintenance
8.1
8.2
8.3
8.4
8.5
8.6
8.7
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Routine Maintenance
Dismantling
Energy Levels
Wavelength Calibration
A to D Calibration
D to A Calibration
Performance Verification
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Section 9 - Circuit Diagrams
9.10 Power Supply Schematic 640 008
9.11 Power Supply Layout 640 008
9.20 Deuterium Lamp Supply Schematic 640 506
9.21 Deuterium Lamp Supply Layout 640 506
9.30 Detector PCB Schematic 640 009
9.31 Detector PCB Layout 640 009
9.32 Detector PCB Schematic 640 505
9.33 Detector PCB Layout 640 505
9.40 Microprocessor PCB Schematic 640 007
9.41 Microprocessor PCB Layout 640 007
9.50 Accessory Driver PCB Schematic 642 003
9.51 Accessory Driver PCB Layout 642 003
Section 10 - Assembly Diagrams
10.1 6400 Final Assembly 640 003
10.2 6405 Final Assembly 640 503
10.3 6400 Lower Case Assembly 640 505
10.4 6405 Lower Case Assembly 640 505
10.5 6400/05 Top Case Assembly 640 005
10.6 6400 Optics Assembly 640 017
10.7 6405 Optics Assembly 640 517
10.8 6400/05 Rear Panel Assembly 640 006
10.9 6400/05 Multi-cell Chamger Assembly 644 002
Section 11 – Spare Parts List
11.01 Packed Instrument
11.02 Top Case Assembly
11.03 Microprocessor PCB
11.04 Lower Case Assembly
11.05 Lamp Housing Assembly
11.06 Monochromator Assembly
11.07 Detector PCB
11.08 Power Supply PCB
11.09 Deuterium Lamp Supply PCB
11.10 Rear Panel Assembly
11.11 Multi-Cell Changer PCB
11.12 Built-In Printer Option
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1.1 About This Manual
This manual covers the service, maintenance, calibration and repair of the Jenway Ltd models 6400 and 6405 Spectrophotometers.
Throughout th is manual all general statements and procedures
should be considered to be relevant for both models. Where a
statement or procedure is relevant to only one of the two models it
will be clearly stated in
relates, at the beginning of the relevant paragraph or sectio n.
This manual must be used in conjunction with the Instruction
Manual for these models, as many of the routine ma intenance
procedures detailed in the Instruction Manual are not repeated in
this Service Manual.
1.2 Using This Manual
underlined italics
, to which model it
This manual is only for the use of Engineers and Technicians who
have successfully completed a Jenway Ltd approved Service
Training cours e on the 6400 and 6405 Spectrophotometers.
Updates to thi s manual will be c irculated through the Jenway Ltd
TSI (Technical Service Inform ation) systems and to other
registered users of this manual. Please complete the form at the rear
of this manual to register your copy for future updates.
In practice Section 2 - Quick Reference and Section 8 –
Maintenance, with the Diagrams in Section 9 and 10, wi ll be most
frequently used, however it is good practice to read the complete
manual initia lly and review it again periodically.
To find the information required refer to the Main Index or Index
to Sections to ide ntify the relevant Section/page number required.
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1.3 Warnings & Safe Practice
Disconnect the mains supply when any covers are removed as there
are high voltages present inside the unit that pose the risk of
electric shock at levels that are hazardous to life!
Do not look directly at the light sources or allow the light beam to
fall directly on the eyes, switch off or dim the lamps (as described
in the procedures) whenever possible and wear UV ey e protection
at ALL times.
Both the UV and visible lamps get very hot when in use, always
allow time for them to cool down before removing them. Always
wear cotton gloves when removing faulty lamps and replacing
them with new ones.
Finger marks, dust and condensation can quickly destroy sensitive
and expensive optical components, always w ear cotton gloves
when the optical b e nch is uncovered and handle any components
by their edges only. Never touch optical surface s. Do not remove
optical covers unless the unit is in a clean, dust and condensation
free environment.
Many of the reagents, solutions and standards used for maintenance
and calibration are corrosive or hazardous, ensure all precautions
supplied with them are followed, where there is any doubt request a
MSDS (Material Safety Data Sheet) from the supplier.
These instrume nts can be used for analysing a broad range of
samples, do not handle them unless you are qualified to do so.
Ensure that the instrument has been correctly decontaminated
before working on it, specifically in areas where the instrument
may have been used for clinical, biological, corrosive or
radioactive samples.
1.4 Standards & Certification
No adjustments should be made to these instruments unless the test
and measurement equipment, signal source or filters to be use d
have a current calibration certificate that is traceable to national or
international standards and that it is known that this test equipment
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is currently performing to the cert ified standard s. All solution s and
reagents should be fresh and within any stated shelf life with a
certificate of analysis.
1.5 Ordering Spares
When ordering spare parts as detailed in this manual please quote
the Part Number and Description. These items should be ordered
from the original supplier of the equipment or your local Jenway
Limited Distributor.
1.6 Returning Items
Should it be necessary to return any item for any reason then this
should be done through the original supplier of the equipment or
your local Jenway Limited Distributor.
1.7 Contacting Jenway Limited
Before contacting Jenway Lim ited please check our we b pages for
any information or updates that may be helpful to you.
www.jenway.com
Emails should be sent to sales@jenway.com
Fax: +44 1371 821083
Phone: +44 1371 820122
Please note no items can be returne d (or will be accepted by)
Jenway Limited without a Returns Authorisation number (RA
number) and a completed Safety Clearance and Decontamination
certificate.
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Section 2
Quick Reference
2.0 About ‘Quick Reference’
2.1 Specification
2.2 Main Sub-Assemblies
2.3 Power Supply Voltages
2.4 Signal Levels
2.5 Error Codes
2.6 Special Key Functions
2.7 Test Solutions
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2.0 About ‘Quick Reference’
This section c ontains a selectio n of the key information that is
often forgotten or difficult to find when required. Use Quick
Reference as a memory jogger, but for more information check out
the references to the main sections on each point.
2.1 Specification
Also see Section 1.2 of the Instruction Manual.
Wavelength Range
6400
6505
320nm to 1100nm
190nm to 1100nm
Wavelength Re solution 0.1nm
Wavelength Acc uracy 1nm
Spectral Bandwidth 5.0nm
Light Source Visible; Tungsten Halogen
Ultra Violet; Deuterium
UV Lamp Auto Off Selectable 320nm to 390nm
Optics Single Beam
Transmittance Range; 0 to 199.9%
Resolution; 0.1%
Accuracy; 0.1% at 10%T
<0.5% at 340nm
Absorbance Range; -0.300A to 3.000A
Resolution; 0.001A
Accuracy; 0.005A at 1.0A
Concentration Range; -300 to 9999
Resolution; 0.001, 0.01, 0.1, 1
Units;ppb, ppm, µgl
-1
, mgl-1, gl-1, M, %, blank.
Spectrum Abs. %T or Conc. A gainst wavelength
Scan Interval Scan Speed
5nm 1200nm/min
1nm 400nm/min
0.2
166nm/min
Stray Light Less than 0.05% @340nm
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2.2 Main Sub-Assemblies
Also see Section 11 – Sp are Parts
640 005 Top Case Assembly – includes the following…
640 058 Keypad
640 007 Microprocessor PCB
012 093 LCD Module
640 504 Lower case Assembly – includes the following…
640 510 Optics Assembly
640 025 Power Supply PCB
640 516 Deuterium Power supply PCB
640 505 6405 Detector PCB
640 009 6400 Detector PCB
644 001 Multi-cell Changer with PCB
060 342 Cooling Fan
010 039 Torroidal Transformer
640 510 Optics Assembly – include s the following…
012 075 Tungsten Halogen lamp
640 508 Deuterium Lamp
650 507 Monochrom ator assembly
032 005 12V Solenoid
Other Items – including…
016 058 1.6A Fuse for 220V supply
016 007 3.15A Fuse for 110V supply
017 050 Mains Switch
009 123 Mains Input Socket
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2.3 Power Supply Voltages
Also see Section 9 - Circuit Diagrams
Before commencing more complex fault finding it is important to
check all the internally generated supply voltage s are correct. The
following list is a useful guide to help quickly check these are
functioning correctly. Not all the points where these voltages can
be measured are given and where the voltage is stated as
unregulated variations may occur. In general regulated supplies
should vary by no more than +/-5% from their nominal value.
Tungsten Lamp Supply
, 12V dc regulated and set by VR1,
measure at PL5 pin 3 with respect to PL5 pin 4 on the p ower
supply PCB and at the terminals on the lamp base with the lamp
fitted.
Solenoid, Relay and Fan Supplies
, 12V dc regulated and pre-set,
measure at PL5 pin 1 with respect to PL5 pin 2 on the pow e r
supply PCB and on the solenoid and fan terminals an d at the
cathode of D3 on the Deuterium Pow e r supply PCB with respect to
0V.
Digital Supply
, 5V dc regulated and pre-set, measure across C17
on the power supply PCB and across C62 on the microprocessor
PCB.
Stepper Motor Drive
, 30V dc unregulated, also acts as
unregulated supply for all above, measure between Star3 and S tar 2
on power supply PCB.
LCD Supply
, -18V dc regu lated and pre-set, measure across the
outside pins of REG. 5 (7918) on the power supply PCB.
DAC Supply,
12V dc regulate d and pre-set, measure across the top
two pins of REG. 4 (7812) on the power supply PCB.
Deuterium PCB Supplies
, 24V dc unregulated, measure across
the top two pins of REG1 (7812) on the Deuterium Lamp Supply
PCB. 12V dc regulated and pre-set, measure across the bottom two
pins of REG. 1 (7812) on the Deuterium Lamp Supply PCB. 5V dc
regulated and pre-set, measure across pins 4 and 8 of IC1 (LM311)
on the Deuterium Lamp Supply PCB. 30V dc unregulated, measure
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from the top of R120 (junction with R100) with respect to the top
of R102 in the centre of the Deuterium Lamp Supply PCB. 14V dc
regulated and pre-set, measure from the top of R101 with respect to
the top of R102 on t he Deuterium Lamp Supply PCB.
Deuterium Lamp Heater
, 2.5V dc (1.0V when arc has struck)
regulated and pre-set, measure across R9 on the Deuterium Lamp
Supply PCB or between the two blue wires on pins 2 and 3 of t he
Deuterium Lamp Socket (SK1).
Deuterium Lamp Arc
, 170V dc pulse d to strike, 300mA at 70V
(Temperature Compensated) whe n arc has struck. Measure across
R119 on the Deu terium Lamp Supp ly PCB and between pins 1 and
3 on the Deuterium Lamp Socket (SK1).
Detector PCB Supplies
, 5Vdc regulated and pre-set, measure
across D2 on the Dete ctor PCB. –5V dc regulated and pre-set,
measure across D3 on the Detector PCB.
Sampling Accessory PCB
, 5Vdc regulated and pre-set, m easure
across C15. 15V dc regulated and pre-set, measure between R18 at
junction with REG 2 and junction of D1 and C22.
2.4 Signal Levels
Also see Section 7.02 - Shutter an d Filters and 8.3 – Energy
Levels
All analogue signal processing is dealt with on the Detector PCB.
Relevant signal s from this PCB are shown in the Diagnostics
Screen as a Voltage, in mV, and CH0, CH1 an d CH2 in ‘counts’
directly from the A to D converter. For more detailed definitions of
these terms see Sec tion 5.3 - Detect or Circuit and Section 7.01 –
The Diagnostics Menu, Section 7.02 – Voltage Display and Section
7.03 Channel Outputs.
The Voltage Display can be used to check lam p energy (ageing),
the correct functioning of the IR Stray Light filter and the U V Stray
Light Filter as well as the Dark Shutter.
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6405
U V Energy
, Set wavelength to 190nm, Dark Shutter open, IR
stray light filter closed, UV second order stray light filter open;
Voltage Display must be greater tha n 20mV.
6400/6405
Visible Energy
, Set wavelength to 805nm, Dark Shutter open, IR
stray light filter open, UV second order stray li ght filter closed;
Voltage Display must be greater than 1000mV and less than
3600mV.
Dark Current
stray light filter closed, UV second order stray light filter open;
Voltage Display should be zero +/- 6mV.
320nm Output
Shutter open, IR stray light filter closed, UV second order stray
light filter open; Voltage Dis play must be greater than 17mV.
2.5 Error Codes
See also Section 8 of the Instruction Manual
A number of dialogue boxes are generated with messages relating
to fault conditions, these are detailed below with a brief description
of some of the most com mon causes for these errors.
Self Test Failure
this message is displayed. The check box for the specific test that
has failed will be marked with a cross (X).
, Set wavelength to 320nm, Dark Shutter closed, IR
, Set wavelength to 320nm, UV lamp off, Dark
, If any of the power-on self tests have been failed
Warning – Operating Parameters Corrupt Restoring To
Default Settings,
This warning message indicates that the contents
of the non-volatile memory has been corrupt ed. This may be due to
a failure of the battery back up, or tha t the battery has become
discharge if the instrument has not been used for s e veral months. It
may also occur by switching off, or a power interruption, during a
save or retrieve o peration. Acceptance of the warning by pressing
the enter key will enable normal operation to contin ue with the
default settings loaded, all previously stored settings will be lost.
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Dark Level Too High
, Sample cham ber cover left open dur ing
start up tests or a calibration, dark shutter stuck open, solenoid or
solenoid drive/connections faulty, Detector PCB failure.
Light Level Too Low
, Blank too optically dense, plastic or glas s
cuvettes used in the UV range, miss-alignment of cell carriage,
wrong lamps fitted, lamps miss-aligned, dark shutter stuck closed.
This may also be due to the contamination of optical surfaces.
Unable To Detect Peak Level
, Cuvette left in sample chamber
during start up tests, miss-aligned cell carr iage, wrong lamps fitted,
miss-aligned lamps or lamp carriage, contaminated optical
component.
Error, Unable to Acquire Dark Level,
This message will be
shown if the dark level cannot be achieved during the start up tests,
possible cause s will be similar to those listed u nder ‘Dark level too
high’ above.
Fatal Error, Calib ration Failure
, Grating position opto-coupler
faulty or connections broken/intermittent, incorrect wavelength
calibration carried out, check connec tions to stepper motor and
check PL3 connections on Power Supply PCB.
Invalid Slope Range
, The standard used to calibrate a
concentration measurement cannot give the standard value enter ed,
this can be beca use the standard is too optically dense or too
similar to the blank. Alternatively the incorrect standard value may
have been entered.
Warning Tungsten Lamp Failure
, Tungsten lamp filament
broken, wrong type of tungsten lamp fitted, no tungsten lamp
fitted, cables to l a mp base broken/damaged, check SK4 on power
supply PCB.
Warning Deuterium Lamp Failure
, Deuterium lamp faulty, cable
disconnecte d, 64 00 set u p as 6405.
Fatal Error, System Calibration Data Failure
, During the start
up test sequence the micropr oce ss or has bee n unab le to detect th e
2
calibration data stored in the E
PROM on the Detector PCB. This
may indicate a faulty Detector PCB or that the connections to the
Detector PCB are not made or are intermitte nt.
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2.6 Special Key Functions
There are a number of special key functions for use by trained
engineers, do not use them unless you are fully conversant with all
the procedures these invoke.
Power On Reset
, Hold the <Enter> key depressed while turning
on the power. This clears the operator set parameters held in nonvolatile memory and is useful in correcting many software
conflicts.
Skip Power On Tests
, Hold the decimal point <.> key depressed
while turning the power on, this function must only be used for
fault finding procedures, taking readings on an instrument started
in this way will produce unpredictable errors.
Diagnostics Mode
, Hold the right arrow <>> key depressed while
turning the power on, do not enter this mode unless you have the
correct training and equipment, making adjustments here can
permanently damage the instrument.
2.7 Test Solutions
1. Holmium Perchlorate – 5% w/v solution of Holmium Oxide in 1.4N
Perchloric acid, this will give absorbance maxima at 241.0, 278.1,
287.0, 361.4, 416.1, 451.1, 485.3, 536.5 and 640.5nm.
2. Potassium Dichromate – 100.0mg/l in 0.005M Sulphuric Acid (use the
Sulphuric Acid as the blank). This will give Absorbance values of
1.071 at 350 nm, 0.484 at 3 13nm, 1.444 at 257nm, 1.242 at 235.
Potassium Dichromate – 50.0mg/l in 0.005M Sulphuric Acid (use the
Sulphuric Acid as the blank). This will give Absorbance values of
0.536 at 350 nm, 0.242 at 3 13nm, 0.722 at 257nm, 0.621 at 235.
3. Sodium Nitrate – 50g/l in de io n ise d wate r, sho uld gi ve les s tha n 0.1%
transmittance at 340nm.
Sodium Iodide – 10g/l in de ionised water, should give le ss than 0.1%
transmittance at 220nm.
All these solutions are hazardous and the manufacturer/suppliers safety
precautions should be carefully followed at all times in preparation, use
and storage.
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Section 3
System Description
3.1 6400 & 6405 Comparison
3.2 Sub-Assemblies
3.3 Accessories
3.4 Outputs
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3.1 6400 & 6405 Comparison
The models 6400 and 6405 share th e majority of com mon subassemblies. However the 6400 is not fitted with the Deuterium
Lamp power Supply PCB and of course the Deuterium Lamp itself.
Because of this the optics and monoc hromator are slightly
different, but in arrangement only.
The Detector, hence Detector PCB is specific to each model,
640 009 for the 6400 and 640 505 for the 6405. (See Section 5.3
Detector Circuit).
3.2 Sub-Assemblies
The 6400 and 6405 can easily be broken down int o sub-assemblies
for the purposes of repair or replacement. All the PCBs are easily
removed, see Section 8.2 – Dismantling. The monochromator and
lamp carriage, which together contain most of the optical
components are both replaceable sub-assemblies. There are a
number of sam pling accessories that can be fitted i nto the sample
compartment and removed with very little disma ntling.
See Section 2.2 for details of the main sub-assemblies and Section
11 for details of other spare parts. The foll owi ng para gra p h lists th e
sampling accessories available.
3.3 Accessories
The following sampling and temperature contr ol accessories are
available, where necessary additional service information for these
accessories is available on re quest. The development of other
sampling accessories is continuous, please check c urrent brochures
www.jenway.com
or
644 001 Motorised Eight Position Cell Holder
644 003 Rack to Hold 10mm Cells for Above
649 001 Water Jacketed Cell Holder as Above
648 001 Water Jacketed Single Cell Holder
642 001 Sipper Pump
647 001 Temperature Controlled Sipper Pump
for up-to-date information.
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645 001 Vacuum Pum p
643 001 Peltier Temperature Control System
646 002 Universal Test Tube Holder
630 003 20 to100mm Single Cell Holder
Other accessories include:
641 001 Internal 40 Column Printer
542 009 Interface Cable Kit
640 133 Dust Cover
3.4 Outputs
The 6400 and 6405 have both analogue and RS232 outputs.
Details of the level of the analogue output for the different ranges
that may be selected on the instruments is given in Section 6.3 of
the Instruction Manual.
Pin configuration for the RS232 socket is given in Section 6.2 of
the Instruction Manual. Section 6.1 of the Instruction Manual gives
details of the various ASCII codes that may be transmitted to the
6400 or 6405 to remotely control them.
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Optical Description
4.1 Light Sources
4.2 Stray Light Filters
4.3 Grating
Section 4
4.4 Signal Detector
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4.1 Light Sources
The model 6400 uses a single Tungsten Halogen lamp to cover its
full wavelength range of 320nm to 1100nm.
The model 6405 uses the same Tungsten Halogen lamp with a ‘see
through’ Deuterium lamp to cover its wavelength range of 190nm
to 1100nm.
The use of the ‘see through’ Deuterium lamp enables both lamps to
be on in the low energy area, found at high UV wavelengths,
reducing the typical energy dip. It also eliminates the spikes
created in systems that use a lamp change over mirror.
It is still possible to switch off the Deuterium lamp to save lamp
life when working only in the visible region and the ‘switch off’
point can be selected between 320nm and 390nm.
The lamps are both pre-aligned and can be simply replaced by
removing the lamp carriage after the lamp access panel has been
removed. See Sectio ns 4.2 and 4.3 of the Instruction Manual.
4.2 Stray Light Filters
6405
The 6405 uses three stray light filters.
The first filter is located between the Tungsten and Deuterium
lamps. This filter is solenoid actuated and is switched into the light
path between 0nm and 390nm to eliminate unwan ted Infra Red
light. (Part number 035 105)
The second filter is located after the Deuterium lamp, inside the
monochromator, is solenoid ac tuated and is switched into the light
path between 390nm and 1100nm to eliminate unwanted UV light.
(Part number 035 109)
The third filter is mechanically linked to the grating mount and is
in the light path between 550nm and 1100nm to eliminate
unwanted second or der diffr act ion. (Part number 035 036)
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6400
The 6400 uses two stray light filters
The first filter i s located after the tu ngsten lamp inside the
monochromator. This filter is solenoid actuated and is switched
into the light path between 0nm and 390nm to eliminate unwanted
Infra Red light. (Part number 035 106)
The second filter is mechanical ly linked to the g r ating mount a nd is
in the light path between 550nm and 1100nm to eliminate
unwanted second or der diffr act ion. (Part number 035 036)
4.3 Grating
The 6400 and 6405 optics use the same grating, this is a concave
holographic grating with 120 0 lines per mm
The grating is dire ctly coupled to the stepper motor, which is under
microprocessor control, thus reducing backlash and mechanical
errors.
4.4 Signal Detector
Photo diode detectors are used on both models; an S1133 type on
the 6400 and the UV enhanced ver sio n S133 7 on the 640 5.
The detector PCB carries out all the analogue signal processing and
each one carries its own calibr ation data stored in an on-boar d
2
E
PROM. The detector PCB also communicates with the
microprocessor to set the instrument for UV/visible (6405) or
visible (6400) operation. For more information see Section 5.3 –
Detector Circuit.
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Section 5
Electronic Description
5.1 Power Supplies
5.2 Deuterium Lamp Supplies
5.3 Detector Circuit
5.4 Microprocessor and Memory Functions
5.5 Accessory Driver PCB
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5.1 Power Supplies
The ac mains supply is reduced by the torroidal transformer giving
five low voltage outputs from the secondary windings. Each
secondary is protected by a re-setable fuse which will go open
circuit when excess current is drawn, when the current is reduced
to normal the fuse will re-set. A 5A fuse is fitted for the 20V
winding, 0.2A fuses for the 15V and 9V windings and 2.5A fuses
for the 16V and 18V windings.
The 20V ac output from the transformer is rectified by D1; the 30V
dc output from this rectifier is used as the input to three L4960
switch mode reg ulators. (REG1, REG 2 and REG 3).
Tungsten Lamp Supply
, The output of the switch mode regulator
REG 3 is set to 12V dc by VR1. The 10K NTC thermistor (R22)
adds temperature compensation to this output voltage reducing
warm up time and thermal drift. The 12V output can be reduced to
5.1V by a logic ‘1’ on the gate of T R5 switching TR3. This
happens during the start up tests to reduce the light level for
accurate zero order detection, it can also be manually instigated by
pressing key 5 when in the Diagnostics Menu. Increased current
flow through t he 0V return from the lamp is detected by TR1 to
confirm that the lamp is functioning (i.e. the lamp filament is
intact).
Solenoid, Relay and Fan Supply
, The output of the switch mode
regulator REG2 is pre-set to 12V. The output to the two fans is via
PL12 pin 1 and 2 and PL5 pins 1 an d 2.
The output to solenoid 1 (Dark Shutter) is via PL1 pin 1 and it is
switched on when SK4 pin 27 goes high, this switches TR2 to
make PL1 pin 4 low .
The output to solenoid 2 (IR Stray Light Filter) is via PL1 pin 2
and it is switc hed on when SK4 pin 22 goes high, this switches
TR4 to make PL 1 pin 5 low.
The output to solenoid 3 (UV (Second Order) Stray Ligh t Filter) is
via PL1 pin 3 and it is switched on when SK4 pin 1 4 goes high,
this switches T R6 to make PL1 pin 6 low.
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The 12V supply to the UV strike relay goes via SK9/PL9 pin 6 to
the Deuterium Lamp supply PCB where it is tracked to the relay.
The relay is switched when SK4 pin 23 goes high switching TR7 to
make SK9/PL9 pi n 7 low.
5V Digital Supply
, The output of the switch mode regulator REG
1 is pre-set to 5V and the output is distributed via SK4 pin 1.
The 15V secondary winding of the tra nsformer is half wave rectified by D 5 and D6 to generate the following s upplies:
LCD and DAC Supplies
, The 7918, -18V regulator gives a -18V
output on SK4 pin 28 this is then routed to the LCD supply. The
7812, 12V regulator gives a 12V output. This is tracked to IC200,
and the associated circuitry that makes up the DAC. Calibration
data for the DAC is stored in the E
5.2 Deuterium Lamp Supplies
In the Deuterium lam p the gas is initially heated by an element
powered at 2.5V . An arc is struck between the Anode and cathode
at around 750V, when the arc is established it is maintained at a
constant curren t of 300mA at 70V whi le the heater voltage is
reduced to 1V.
2
PROM IC201.
A local supply of 12V dc is gener a ted from the 16V ac winding of
the transformer. This 12V supply is then used to generate a
regulated 5V supply.
The 20V ac winding of the transformer is used to genera te an
unregulated 30V su pply.
The boost regulator circuit based around the pulse width modulator
IC100 uses this 30V to generate a 170V supply. This supply is then
switched across the auto-transformer L2 by relay RLY1a to
increase this voltage to about 750V, s ufficient to strike the arc.
When the arc has been struck IC101a and TR100 maintain the
current at 300mA. Power is kept to a minimum at vary ing
temperatures by R122, a 10K NTC Thermistor. TR101 detects the
current flow and an output is sent to the microprocessor via PL9
pin 11.
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The heater voltage is generated by the high side driver IC2, this
will be 2.5V un til a signal from the microprocessor, iso lated by IC3
switches the comparator IC1a, which in turn reduces the heater
voltage to 1V. The watchdog IC4 ensures that the comparator is
continually updated.
5.3 Detector Circuit
Detectors and Amplifiers
The detector PCB’s (6 40 009 for the 6400 and 640 505 for the
6405) are identical except for the photodiode detector and the preset programming that determines whether the unit is either a 6400
or 6405. The photodiodes fitted will be an S1133 for the Model
6400 or the UV enhanced version S1337 for the 6405.
The current through the de tec tor is pr op or tio na l to the inc id ent
light. IC3a acts as a current to voltage converter, the gain being set
by the feedback resistors in the T network.
IC1 is a low pass filter that attenuates frequencies of 50Hz or
greater from the signal. In normal operation pins 3 and 4 of SK2
are linked so the signal passes to the three remaining amplifiers of
IC1. IC1b is set for unity gain, IC1c has a gain of 10 a nd IC1d a
gain of 100.
A to D Conversion
Each of these amplified signals then pass into the first three
channels (CH0 to CH2) of an 8 channel, 12 bit, serial, A to D
converter.
All three channels are converted and the microproces sor selects the
channel that gives the best resolution without reaching saturation
(32767 counts). In effect this means CH2 will be selected for inputs
up to 40mV, CH1 for inputs up to 400mV and CH0 f or inputs up to
4.0V.
The A to d converter requires a reference voltage of 4.096V which
is generated from the –5V rail by D4, this is inve rted to a positive
value by IC5d and fed to pin 14, Ref +, of the A to D converter,
IC2.
The E
2
PROM, IC4, maintains calibration data for the PCB, see
Section 8.6 - A to D Calibration as well as programming the unit
for visible (6400) or UV/visible (6405) operation.
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5.4 Microprocessor and Memory Functions
EPROM
IC3 is a 256K byte E P ROM that contains the software code f or the
executable programme. Its label will show the software version
number and date it was programmed.
RAM
User Variables that are input during oper ation are stored in batte ry
backed RAM (IC1 supported by Bat 1). User variables are data
generated from operator input for values such as wavelength limits
for scanning, calibration data for concentration and quantitation
measurements, run time for kinetics etc, etc. These values can be
re-set to their factory set default values by the Reset Parameters
function in the Instrument Setu p Menu or by performing a power
on re-set, see Secti on 2.6, Special Ke y Functions.
Peripherals
Active time and date information is generated and stored by the
real time clock IC18, the data stored here can be re-set through the
‘Clock Setup’ function in the ‘Instrum ent Setup’ menu.
IC2 is the ‘watchdog’, which monitors the supplies and back up
battery. It re-sets the instrument if these fall below critical levels.
The optional internal printer is driven dir ectly from the
microprocessor via PL3. Under no circumstances should this
device be connected or disconnected with power supplied to the
instrument.
Microcontroller
IC5 is the microco ntroller, a Hitachi H 8/3002 device running at
12MHz. This integrates system support functions together with an
H8/300H CPU core with a 32 bit internal architecture. Of the
system support functions the internal timer (ITU), serial
communications interface (SCI), A to D converte r and I/O ports are
used to reduce the number of external components required.
Display Drive and Contrast
IC4 and IC6 are used to reduce the clock speed for running the
LCD. The LCD contrast is pre-set in manufacture by VR1 and
temperature compensated by TR1 at 1 0mV per degree C. Opera tor
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adjustment of the contrast is through the software via the digital
potentiometer IC13, this adjusts the output of IC11a to values
around –10V at VLCD on PL1.
Keypad and RS232 Interface
The keypad interface uses the A to D converter built into the
microcontroller. The eight resistors, R21 to R28 form a potential
divider from the +5V to 0V levels. This give s 7 discreet voltage
levels on pins 4 to 10 of PL4. These form a matrix with the 3
keypad input ports (KEYINP0, KEYINP1, KEYINP2) on PL4 pins
1,2 and 3. In this way up to 21 keys can be recognised by a specific
voltage on its re levant port.
The RS232 output is generated by IC8 and routed via PL2 to the
power supply PCB and hence to the rear panel socket.
5.5 Accessory Driver PCB
Both 6400 and 6405 models can be fitted with the optional
Accessory Driver PCB. This is capable of driving all internal
sampling accessories and makes available supplies and controls for
driving external modules such as the peltier/si pper accessory.
Local supplies of 5V and 12V are generated from the 18V ac
winding of the transformer.
The Accessory Driver PCB has it’s own on-boa r d m icro-con trol ler
which has a permanent master/slave relationship with the ma in
microprocessor.
The Accessory Driver is on the Serial Peripheral I nterface Bus
(SPIBus) and is selected by the CSACC line.
The on-board E
2
PROM ma intains calibratio n data for the fitted
accessory. In the case of the multi-cell changer this includes the
number of steps on the stepper motor from the sensor vane to the
first sample position. This will vary from accessory to accessory,
so the PCB and mechanical as sembly must be treated as a matched
pair in this instance.
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Software Description
6.0 Warning
6.1 Start Up Routine
Section 6
6.2 Main Menu
6.3 Menu Options
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