service manual spectrophotometer model spv-72 · power supply ： ac:220/110v±10%，50/60hz...

SERVICE MANUAL SPECTROPHOTOMETER

Model SPV-72

SCO-TECH Auf der Heide 15 D-37351 Dingelstädt Federal Republic of Germany Tel. +49 (0) 36075 439 306 Fax +49 (0) 36075 439 309 e-mail [email protected] www.sco-tech.com

Stand : 19.10.2011 RV / 30.03.12 MA

SERVICE MANUAL - SPECTROPHOTOMETER Model SPV-72

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CONTENTS

Points for attention .......................................................................................................... 3 Specifications of instrument........................................................................................... 4 Chapter One Descriptions of instrument ...................................................................... 5

1.1 Outer construction of spectrophotometer ....................................................... 5 1.2 Inner construction of spectrophotometer......................................................... 6

Chapter Two Circuit descriptions of instrument ........................................................... 7

2.1 One-chip computer board.................................................................................. 7 2.2 Pre-amplification board ....................................................................................... 7 2.3 Conversion board of LCD .................................................................................... 8 2.4 System power supply board (power supply of tungsten lamp) .................... 9

Chapter Three Inspection of instrument specifications............................................. 10

3.1Wavelength accuracy ........................................................................................ 10 Chapter Four Adjustment of instrument...................................................................... 11

4.1 Basic adjustment of instrument ......................................................................... 11 4.2 Troubleshooting ................................................................................................... 15

Appendix 1：Preparation method for standard solution ......................................... 16

（1）Potassium dichromate..................................................................................... 16 （2）Sodium iodide................................................................................................... 16 （3）Sodium nitrite .................................................................................................... 17

APPENDIX 2：Circuit diagram ..................................................................................... 18

(1) One-chip computer board................................................................................ 18 （2) Port ....................................................................................................................... 19 （3）Conversion board of LCD............................................................................... 20 （4）Pre-amplification board.................................................................................. 21


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Points for attention

The following conditions must be satisfied when installing the instrument.

Avoid the sunlight shinning directly and bigger gas flow;

Don’ put it in the room with dust and corrosion gases;

Avoid the place with extensive vibration and continued vibration.

Far away from the electronic devices of magnetic, electric fields and high

frequency magnetic wave.

Put the instrument on a stable, firm and even work-bench. The rear of the

instrument to the walls should be at least over 15cm in order to keep

effective ventilating and dissipating heat.

Avoid high temperature and high humidity environment.

Room temperature: 5°C～35°C

Room humidity: ≤85%

Power supply：AC 220 V±22V, 50 Hz±1Hz. Total power is about 180VA.The

electric supply system should be required to be the three- phase four-wire

grounded protection system.

Be secure that the instrument is reliably grounded. The purified regulated

power supply should be used if it is possible.


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Specifications of instrument

Wavelength range: 320nm～ 1100nm

Wavelength accuracy： ≤±2.0nm

Wavelength reproducibi l i ty： ≤1nm

Transmittance accuracy： ≤± 0.5%T

Transmittance reproducibi l i ty:≤0.3%T

Stray light： ≤0.1% (NaNO2，340nm)

Spectral bandwidth： 5nm（option: 1nm， 2nm， 4nm,）

0%τstability: ≤0.2%τ/30min

100%τstability: 0.001A/30min(500nm，After preheating)

Measurement mode： T,A,C,E

Photometr ic range： -0.3A～3A

Display： 16×2 LCD

Reciever： Silicon photodiode

Light source： Tungsten lamp

Power supply ： AC:220/110V±10%，50/60HZ

Power： 100W

Dimension: 530×410×210mm

Weight： 15kg


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Chapter One Descriptions of instrument

1.1 Outer construction of spectrophotometer

Front view of instrument

Rearview of instrument

Fan RS232interface Printer port Supply plug-in

Fuse Screw

Keyboard Wavelength adjust button LCD

Sample

chamber door

Wavelength indicating window

Sample cell handle


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NOTE:

Black switch at right side of instrument is the switch of power supply;

1.2 Inner construction of spectrophotometer

Single-board microcomputer Lamp housing

Receiver Monochromator

System supply board


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Chapter Two Circuit descriptions of instrument

2.1 One-chip computer board

(1)Functions：Handle with the magnified signal on the pre-amplifying board and control LCD

display, keyboard, printing and series interfaces

(2)Test point： +5Vtest terminal voltage on GND should be 5V.

2.2 Pre-amplification board

Function：Test the light signal and make the amplification.


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2.3 Conversion board of LCD

Function：Converse the single row interface of LCD into the interface used by the instrument.

Adjusting terminal: RP1 is contrast control terminal of LCD display, the adjustment procedures

are as follows:

Open the main switch of the instrument, the instrument model is displayed on LCD, afterwards,

display the current transmittance and absorbance. Adjust the potentiometer RP1 located on LC

conversion board until dark spot lightness of character block on LCD will be shown as the same

as the background. That is the whole black character block can not be viewed, the clear

characters are displayed. That shows the adjustment is successful.


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2.4 System power supply board

(power supply of tungsten lamp)

(1)Function：Provide the working voltage for the computer board and the tungsten lamp.

(2)Test terminal：Measure the voltages among the terminals under the condition of switching on

the instrument.

The voltage is 5V between 5V and GND2;

The voltage is 12V between 12V and GND2;

The voltage is 9V between 9V and GND.

If it is not so, please replace a new board.


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Chapter Three Inspection of instrument specifications

3.1 Wavelength accuracy

When swi tching on the inst rument for preheating i t at least for 30minutes, put

the didymium f i l ter into the sample cel l , move i t to the optical path, rotate the

wavelength hand-wheel wi th s ingle way nearby 529.8nm ， read out the

wavelength value corresponded when the minimum value i s di splayed on LCD.

I t should be sat i s f ied wi th the wavelength of 529.8nm±2.0nm. Again rotate the

wavelength hand-wheel wi th one way nearby 807.7nm, read out the

wavelength value corresponded when the minimum value i s di splayed on LCD.

I t should be sat i s f ied wi th 807.7nm±2.0nm(the standard value of the didymium

f i l ter i s provided by National S tandard Substance Center) .

3.2 100 %τ stability：Drift ≤0.5%τ within 3min.

When swi tching on the inst rument for preheat ing i t at least for 30minutes , press

100%τkey（ at the wavelength of 500nm） . Adjust 100%τ， observe i t for 3min，

the change of the t ransmi ttance value should be in accord wi th the

speci f icat ion s t ipulated.

3.3 0%τ stability：Drift ≤0.3τ within 3min

When swi tching on the inst rument for preheating i t at least for 30minutes, put

the l ight b lock into the sample cel l to block the optical path， press 0%τkey to

adjust 0%T，observe i t for 3min，the change value should be in accord wi th the

speci f icat ion s t ipulated.


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Chapter Four Adjustment of instrument

4.1 Basic adjustment of instrument

There are two parts requiring the user to make the adjustment and replacement by itself, such

as: adjustment of the

light source and correction of wavelength translation. The followings are respectively described:

4.1.1 Adjustment of l ight source

During the operation, if it is found that the light source is needed to be replaced or adjusted,

please follow the following operation procedures:

L ight source chamber

Tungsten lamp Screw of tungsten lamp


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Wir ings of W lamp

(1) Replacement of W lamp

a) After switching off the instrument, take off three screws located at the outer cover of

the instrument and detach the wavelength adjust knob, carefully take off the outer

cover of the instrument, and detach the cover of the lamp chamber. The moment, you

can see the light source chamber as shown in the above Figure.

NOTE: Don’t change the wiring of the instrument. Try to find the connecting row of the

Tungsten lamp and refer to the above diagram, do it as follows:

b) Loose the two screws fixed W lamp lead-in wiring on the connecting row, pull out the

two lead-in wirings of W lamp right up from the wiring row of the W lamp;

c) Loose the fixed screws (refer to the diagram of the light source), take out the W lamp

right up from the W lamp holder.

d) Carefully insert a new W lamp into its holder, the two lead wires of W lamp will pass

through the bottom part of W lamp to the position of the wiring row. Tighten the screws

at the original installing position. And then connect the lead-in wires of W lamp to the

wiring row and tighten the connection screws.

Wiring of tungsten Lamp lamp

Wiring screw of tungsten lamp


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(2) Adjustment of W lamp：

Switch on the instrument, set the wavelength to be 500nm, observe the light spot of W lamp in

the position of the slit as shown in the following Figure. The light spot should be located the

center of the slit

If the light spot is located at the center position, loose the fixed screw of W lamp and adjust up

and down positions of W lamp to make the light spot striking on the center of the slit, afterwards,

tighten the fixed screws of W lamp.

Put on the outer cover of the instrument again.

4.1.2 Correct ion of wavelength t rans i t ion

（1）Diagnosis of wavelength transition：

The didymium filer of 529.8nm、807.7nm are used as the standard for the correction of the

wavelength transition (The standard value should be approved by State Substance Center).

a) Adjust the wavelength nearby 529.8nm

b) Use the blank to adjust 100%T(when the blank is in the sample cell, press 100％T key）.

c) Put the didymium filter into the optical path of the sample chamber, slowly adjust the

wavelength button forth and back to make the value showing the minimum value on LCD,

record the current wavelength value A.

d) Rotate the wavelength button nearby 807.7nm， slowly adjust the wavelength button forth

and back to make the value showing the minimum value on LCD, record the current

wavelength value B.

e) If the wavelength value A and B are 529.8nm and 807.7nm，that shows there is no

wavelength transition occurring. Otherwise check if two wavelengths are increased or

decreased to a coefficient value at the same time. If it is so, that shows the wavelength

transition is occurred. In this case, the correction can be made by user self.


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（2）Operation procedures for correcting the wavelength transition：

a) After switching off the instrument, loose three screws located at the rear of the outer cover

of the instrument, take off the wavelength adjust button, carefully take out the outer cover

of the instrument from its rear towards up as shown in the following Figure.

b) Adjust the wavelength adjust shaft 3 to make the wavelength minimum value at the

wavelength A displaying on LCD. Loose the screw 1, adjust the wavelength dial 2，turn the

wavelength dial value to 529.8nm，again tighten the screw 1.

c) Turn the wavelength adjust shaft 3 to the wavelength value of 807.7nm，slowly adjust the

wavelength forth and back to make the displayed value being the minimum value on LCD.

Observe if the wavelength value displayed is 807.7nm. If it is so, retrieve the wavelength

adjust button. That shows the correction of the wavelength transition is completed. If it is

not so, repeat the operation procedures mentioned above again.


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4.2 Troubleshooting

Error Possible Cause Solution

No display when switching on the instrument Lamp is not lit.

1. Power supply is cut off. 2. The fuse is broken.

1. Check cables of power supply 2. Replace a new fuse.

It is normal after switching on instrument, but lamp is not lit.

Lamp is damaged

Replace a new lamp.

Measurement result is not correct

1. Wavelength dial is loosening. 2. Wavelength is transited; 3. Light is blocked by the cell holder; 4. Light source is not stable.

1. Make the correction of the wavelength transition; 2. Check the power supply of the optical path.

The data displayed is not stable

1. May be block matter in sample chamber; 2. Environmental humidity is too big; 3. Lamp is damaged; 4. There is suspended substance in the determined sample 5. Power supply is not stable.

1. Remove the blocking element; 2. Work under dry area; 3. Open light source chamber at rear of instrument, observe if the brightness changes light and dark. If it is so, replace a new lamp;; 4. Replace sample to be determined; 5. Check the power supply.


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Appendix 1：Preparation method for standard solution

(1）Potassium dichromate

Spectral bandwidth: 2nm (Nation standard substance GBW（E）130066)

a) Standard value：

b) Preparation of solution：

Accurately take 60g reference potassium dichromate dried with 120� to constant weight, use

0.005mol/l sulfuric acid to dissolve it and dilute it to 1000ml. Measure it at the wavelength

stipulated and calculate the absorbance coefficient, and then it is compared with the

absorbance coefficient stipulated, the relative deviation should be within ±1%.

（2）Sodium iodide

Put sodium iodide (AR degree) into baking oven with 105C ±5C for 2hours, and then put it into

drying cabinet for cooling down until to the room temperature. Take 5.0g（±0.01g）into 100ml

beaker，when it is dissolved with about 40ml distilled water, transfer it to 500ml measuring flask.

Purge the beaker for three times with a small amount of the distilled water and put it into the

measuring flask with the purged water together. Dilute it to the scale mark with the distilled

water, shaking it up uniformly. It is 10g/L sodium iodide solution.

Temperature/ wavelength 235nm 257nm 313nm 350nm

10°C 18.0 13.5 51.2 22.6

15°C 18.0 13.6 51.3 22.7

20°C 18.1 13.7 51.3 22.8

25°C 18.1 13.7 51.3 22.9

30°C 18.2 13.8 51.3 22.9


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（3）Sodium nitrite

Put sodium nitrite (AR degree) into 105C ±5C baking oven for 2hours，then put it into drying

cabinet for cooling down until to the room temperature. Take 5.0g（±0.01g）into 100ml beaker.

When it is dissolved with about 40ml distilled water, transfer it to 100ml measuring flask. Purge the

beaker for three times with a small amount of the distilled water and put it into the measuring

flask with the purged water together. Dilute it to the scale mark with the distilled water, shaking it

up uniformly. It is 50g/L sodium nitrite solution.


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APPENDIX 2：Circuit diagram

(1) One-chip computer board


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（2) Port


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（3）Conversion board of LCD


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（4）Pre-amplification board

service manual spectrophotometer model spv-72 · power supply ： ac:220/110v±10%，50/60hz...

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