Loading...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
1.0Index to Sections
1.1About This Manual
1.2Using This Manual
1.3Warnings & Safe Practice
1.4Standards & Certification
1.5Ordering Spares
1.6Returning Items
1.7Contacting Jenway Limited
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Introduction.
1.0 Index to Sections Section 1 – Introduction
1.0Index to Sections
1.1About This Manual
1.2Using This Manual
1.3Warnings & Safe Practice
1.4Standards & Certification
1.5Ordering Spares
1.6Returning Items
1.7Contacting Jenway Limited
Section 2 - Quick Reference
2.0About ‘Quick Reference’
2.1Specification
2.2Main Sub-Assemblies
2.3Power Supply Voltages
2.4Signal Levels
2.5Error Codes
2.6Special Key Functions
2.7Test Solutions
Section 3 - System Description
3.16400 & 6405 Comparison
3.2Sub-Assemblies
3.3Accessories
3.4Outputs
Section 4 - Optical Description
4.1Light sources
4.2Stray Light Filters
4.3Grating
4.4Signal Detector
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Section 5 - Electronic Description
5.1Power Supplies
5.2Deuterium Lamp Supplies
5.3Detector Circuit
5.4Microprocessor and Memory Functions
5.5Accessory driver PCB
Section 6 - Software Description
6.0Warning
6.1Start Up Routine
6.2Main Menu
6.3Menu Options
Section 7 – Diagnostics
7.1The Diagnostics Menu
7.2Shutter and Filters
7.3Lamp Control
7.4Zero Order Cal.
7.5Calibrate Functions
7.6Wavelength Functions
7.7Channel Outputs
7.8Voltage Display
7.9Motor Position sensor
Section 8 – Maintenance
8.1Routine Maintenance
8.2Dismantling
8.3Energy Levels
8.4Wavelength Calibration
8.5A to D Calibration
8.6D to A Calibration
8.7Performance Verification
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Section 9 - Circuit Diagrams
9.10Power Supply Schematic 640 008
9.11Power Supply Layout 640 008
9.20Deuterium Lamp Supply Schematic 640 506
9.21Deuterium Lamp Supply Layout 640 506
9.30Detector PCB Schematic 640 009
9.31Detector PCB Layout 640 009
9.32Detector PCB Schematic 640 505
9.33Detector PCB Layout 640 505
9.40Microprocessor PCB Schematic 640 007
9.41Microprocessor PCB Layout 640 007
9.50Accessory Driver PCB Schematic 642 003
9.51Accessory Driver PCB Layout 642 003
Section 10 - Assembly Diagrams
10.16400 Final Assembly 640 003
10.26405 Final Assembly 640 503
10.36400 Lower Case Assembly 640 505
10.46405 Lower Case Assembly 640 505
10.56400/05 Top Case Assembly 640 005
10.66400 Optics Assembly 640 017
10.76405 Optics Assembly 640 517
10.86400/05 Rear Panel Assembly 640 006
10.96400/05 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
11.09Deuterium Lamp Supply PCB
11.10Rear Panel Assembly
11.11Multi-Cell Changer PCB
11.12Built-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 this 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 underlined italics, to which model it relates, at the beginning of the relevant paragraph or section.
This manual must be used in conjunction with the Instruction Manual for these models, as many of the routine maintenance procedures detailed in the Instruction Manual are not repeated in this Service Manual.
1.2 Using This Manual
This manual is only for the use of Engineers and Technicians who have successfully completed a Jenway Ltd approved Service Training course on the 6400 and 6405 Spectrophotometers.
Updates to this manual will be circulated through the Jenway Ltd TSI (Technical Service Information) 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, will be most frequently used, however it is good practice to read the complete manual initially and review it again periodically.
To find the information required refer to the Main Index or Index to Sections to identify 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 eye 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 wear cotton gloves when the optical bench is uncovered and handle any components by their edges only. Never touch optical surfaces. 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 instruments 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 used 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 certified standards. All solutions 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 Limited please check our web 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 returned (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
2.0About ‘Quick Reference’
2.1Specification
2.2Main Sub-Assemblies
2.3Power Supply Voltages
2.4Signal Levels
2.5Error Codes
2.6Special Key Functions
2.7Test Solutions
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2.0 About ‘Quick Reference’
This section contains a selection 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 320nm to 1100nm |
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6505 190nm to 1100nm |
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Wavelength Resolution |
0.1nm |
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Wavelength Accuracy |
1nm |
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Spectral Bandwidth |
5.0nm |
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Light Source |
Visible; Tungsten Halogen |
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Ultra Violet; Deuterium |
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UV Lamp Auto Off |
Selectable 320nm to 390nm |
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Optics |
Single Beam |
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Transmittance |
Range; 0 to 199.9% |
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Resolution; 0.1% |
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Accuracy; 0.1% at 10%T |
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<0.5% at 340nm |
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Absorbance |
Range; -0.300A to 3.000A |
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Resolution; 0.001A |
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Accuracy; 0.005A at 1.0A |
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Concentration |
Range; -300 to 9999 |
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Resolution; 0.001, 0.01, 0.1, 1 |
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Units;ppb, ppm, gl-1, mgl-1, gl-1, M, %, blank. |
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Spectrum |
Abs. %T or Conc. Against wavelength |
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Scan Interval |
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Scan Speed |
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5nm |
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1200nm/min |
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1nm |
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400nm/min |
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0.2 |
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166nm/min |
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Stray Light |
Less than 0.05% @340nm |
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2.2 Main Sub-Assemblies
Also see Section 11 – Spare 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 – includes the following…
012 075 Tungsten Halogen lamp
640 508 Deuterium Lamp
650 507 Monochromator 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 voltages 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 power 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 power supply PCB and on the solenoid and fan terminals and at the cathode of D3 on the Deuterium Power 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 Star 2 on power supply PCB.
LCD Supply, -18V dc regulated and pre-set, measure across the outside pins of REG. 5 (7918) on the power supply PCB.
DAC Supply, 12V dc regulated 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 the 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 the Deuterium Lamp Socket (SK1).
Deuterium Lamp Arc, 170V dc pulsed to strike, 300mA at 70V (Temperature Compensated) when arc has struck. Measure across R119 on the Deuterium Lamp Supply 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 Detector PCB. –5V dc regulated and pre-set, measure across D3 on the Detector PCB.
Sampling Accessory PCB, 5Vdc regulated and pre-set, measure 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 and Filters and 8.3 – Energy Levels
All analogue signal processing is dealt with on the Detector PCB. Relevant signals from this PCB are shown in the Diagnostics Screen as a Voltage, in mV, and CH0, CH1 and CH2 in ‘counts’ directly from the A to D converter. For more detailed definitions of these terms see Section 5.3 - Detector 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 lamp energy (ageing), the correct functioning of the IR Stray Light filter and the UV 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 than 20mV.
6400/6405
Visible Energy, Set wavelength to 805nm, Dark Shutter open, IR stray light filter open, UV second order stray light filter closed; Voltage Display must be greater than 1000mV and less than 3600mV.
Dark Current, Set wavelength to 320nm, Dark Shutter closed, IR stray light filter closed, UV second order stray light filter open; Voltage Display should be zero +/- 6mV.
320nm Output, Set wavelength to 320nm, UV lamp off, Dark Shutter open, IR stray light filter closed, UV second order stray light filter open; Voltage Display 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 common causes for these errors.
Self Test Failure, If any of the power-on self tests have been failed this message is displayed. The check box for the specific test that has failed will be marked with a cross (X).
Warning – Operating Parameters Corrupt Restoring To Default Settings, This warning message indicates that the contents of the non-volatile memory has been corrupted. This may be due to a failure of the battery back up, or that the battery has become discharge if the instrument has not been used for several months. It may also occur by switching off, or a power interruption, during a save or retrieve operation. Acceptance of the warning by pressing the enter key will enable normal operation to continue with the default settings loaded, all previously stored settings will be lost.
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Dark Level Too High, Sample chamber cover left open during 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 glass 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 carriage, 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 causes will be similar to those listed under ‘Dark level too high’ above.
Fatal Error, Calibration Failure, Grating position opto-coupler faulty or connections broken/intermittent, incorrect wavelength calibration carried out, check connections 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 entered, this can be because 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 lamp base broken/damaged, check SK4 on power supply PCB.
Warning Deuterium Lamp Failure, Deuterium lamp faulty, cable disconnected, 6400 set up as 6405.
Fatal Error, System Calibration Data Failure, During the start up test sequence the microprocessor has been unable to detect the calibration data stored in the E2PROM on the Detector PCB. This may indicate a faulty Detector PCB or that the connections to the Detector PCB are not made or are intermittent.
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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 350nm, 0.484 at 313nm, 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 350nm, 0.242 at 313nm, 0.722 at 257nm, 0.621 at 235.
3.Sodium Nitrate – 50g/l in deionised water, should give less than 0.1% transmittance at 340nm.
Sodium Iodide – 10g/l in deionised water, should give less 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
3.16400 & 6405 Comparison
3.2Sub-Assemblies
3.3Accessories
3.4Outputs
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3.1 6400 & 6405 Comparison
The models 6400 and 6405 share the majority of common 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 monochromator 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 into 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 sampling accessories that can be fitted into the sample compartment and removed with very little dismantling.
See Section 2.2 for details of the main sub-assemblies and Section 11 for details of other spare parts. The following paragraph lists the sampling accessories available.
3.3 Accessories
The following sampling and temperature control accessories are available, where necessary additional service information for these accessories is available on request. The development of other sampling accessories is continuous, please check current brochures or for up-to-date information.
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
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645 001 Vacuum Pump
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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Section 4
Optical Description
4.1Light Sources
4.2Stray Light Filters
4.3Grating
4.4Signal 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 changeover 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 Sections 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 unwanted Infra Red light. (Part number 035 105)
The second filter is located after the Deuterium lamp, inside the monochromator, is solenoid actuated 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 order diffraction. (Part number 035 036)
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6400 The 6400 uses two stray light filters
The first filter is located after the tungsten 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 mechanically linked to the grating mount and is in the light path between 550nm and 1100nm to eliminate unwanted second order diffraction. (Part number 035 036)
4.3 Grating
The 6400 and 6405 optics use the same grating, this is a concave holographic grating with 1200 lines per mm
The grating is directly 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 version S1337 on the 6405.
The detector PCB carries out all the analogue signal processing and each one carries its own calibration data stored in an on-board E2PROM. 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
5.1Power Supplies
5.2Deuterium Lamp Supplies
5.3Detector Circuit
5.4Microprocessor and Memory Functions
5.5Accessory 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 regulators. (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 TR5 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 the 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 and 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 switched on when SK4 pin 22 goes high, this switches TR4 to make PL1 pin 5 low.
The output to solenoid 3 (UV (Second Order) Stray Light Filter) is via PL1 pin 3 and it is switched on when SK4 pin 14 goes high, this switches TR6 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 pin 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 transformer is half wave rectified by D5 and D6 to generate the following supplies:
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 E2PROM IC201.
5.2 Deuterium Lamp Supplies
In the Deuterium lamp 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 current of 300mA at 70V while the heater voltage is reduced to 1V.
A local supply of 12V dc is generated 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 generate an unregulated 30V supply.
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, sufficient 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 varying 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 until a signal from the microprocessor, isolated 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 (640 009 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 detector is proportional to the incident 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 and 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 microprocessor 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 for 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 inverted to a positive value by IC5d and fed to pin 14, Ref+, of the A to D converter, IC2.
The E2PROM, 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 EPROM that contains the software code for the executable programme. Its label will show the software version number and date it was programmed.
RAM
User Variables that are input during operation are stored in battery 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 Setup Menu or by performing a power on re-set, see Section 2.6, Special Key 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 ‘Instrument 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 directly 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 microcontroller, a Hitachi H8/3002 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 converter 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 10mV per degree C. Operator
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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 gives 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 relevant 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/sipper 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-board micro-controller which has a permanent master/slave relationship with the main microprocessor.
The Accessory Driver is on the Serial Peripheral Interface Bus (SPIBus) and is selected by the CSACC line.
The on-board E2PROM maintains calibration 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 assembly must be treated as a matched pair in this instance.
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Section 6
Software Description
6.0Warning
6.1Start Up Routine
6.2Main Menu
6.3Menu Options
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