Pointe 180 Service Manual Rev D PDF
Pointe 180 Service Manual Rev D PDF
Pointe 180 Service Manual Rev D PDF
D 59
1900Series
Service Manual
Table of Contents
Introduction .......................................... 1 Replacement Parts .............................. 40
Layout ................................................... 2 Block Diagram .................................... 41
Principles of Operation ......................... 6 PCB Layouts ....................................... 42
Photometer ............................................. 6 Main PCB–from rev Z .......................... 42
Display, Keypad, and Printer ................... 6 Main PCB–from rev L to rev Y .............. 43
Temperature control ................................ 6 Main PCB–through rev K ...................... 44
System Control ....................................... 7 Printer PCB (300-200E) ........................ 45
Troubleshooting .................................... 9 Printer PCB (300-200) .......................... 46
Power Supply ......................................... 9 Incubation Block PCB ........................... 47
Photometer ............................................. 9 Schematics .......................................... 48
Temperature Control ............................. 11 Main PCB (from rev Z) 1 of 4 ................ 48
Main PCB ............................................ 11 Main PCB (from rev Z) 2 of 4 ................ 49
Internal Printer ..................................... 11 Main PCB (from rev Z) 3 of 4 ................ 50
Display ................................................ 11 Main PCB (from rev Z) 4 of 4 ................ 51
Keypad ................................................ 11 Main PCB (rev L to rev Y) 1 of 4 ........... 52
Serial Port ............................................ 11 Main PCB (rev L to rev Y) 2 of 4 ........... 53
Error Messages ..................................... 13 Main PCB (rev L to rev Y) 3 of 4 ........... 54
ServiceProcedures .............................. 14 Photometer PCB (from rev L) ................ 55
Opening the Instrument ......................... 14 Printer PCB (300-200E) ........................ 56
Lamp Replacement ............................... 16 Printer Interface PCB (300-200) ............. 57
Filter Replacement ................................ 18 Incubation block PCB ........................... 58
Filter Label .......................................... 20
Printer Jams ......................................... 21
Printer Repairs ..................................... 22
Print Head Replacement .................. 22
Printer Platen Replacement .............. 24
Printer Interface PCB Replacement ........ 25
Main PCB and/or
Photometer Replacement ....................... 26
Calibration ......................................... 30
Software or Hardware Calibration? ........ 30
Software Calibration ............................. 32
Restore Calibration Data ................. 33
Reset Calibration Data .................... 34
Software Calibration – Temperature . 35
Software Calibration – Absorbance .. 36
Hardware Calibration ............................ 37
Hardware Calibration – Temperature 37
Hardware Calibration – Absorbance . 39
© 1994 - 1997 Awareness Technology, Inc. Unauthorized duplication is prohibited. Information given in this manual is
restricted for use by authorized personnel and is to be used for the sole purpose of providing routine instrument maintenance
and repair service. No part of this manual may 1900beSeries
copiedService Manualwithout the express consent of Awareness
or redistributed
© 1994 - 1997 Awareness
Technology, Inc. ThereTechnology, Inc.
is no transfer of Unauthorized duplicationtrade
technology, copyright, is strictly prohibited.
name, patent, Information givenorinother
trade secret, this manual is restricted
proprietary right
given
for useor
byimplied.
authorized personnel and is to be used for the sole purpose of providing routine instrument maintenance and repair Revservices.
D 7/97
Rev. D 1
Introduction
This manual describes service and troubleshooting procedures for 1900 series instruments. This
manual is written with the service technician in mind, and contains no information for clinical
chemistry analysis, or other applications. For details on instrument operation and specifications,
please refer to the Owner's Manual specific to the instrument.
WARNING
Layout
Figure 1 shows the exterior of the instrument, Figure 2 shows the rear panel, Figure 3 shows the
internal chassis layout, and Figure 4 shows the bottom of the instrument.
The instrument housing is comprised of a chassis (base and rear panel combined) and a formed plastic
cover. The cover is secured to the base by five #4 self-tapping screws.
A 16-character alphanumeric LED display is mounted to the printer bracket inside of the cover. A
20-column thermal printer and the printer PCB mount to a metal printer bracket, which in turn mounts
to the inside of the cover. The display and the printer assembly both connect to the main PCB via 14-
conductor ribbon cable terminated with DIP (dual in-line pin) plugs. The keypad is a membrane-
switch type sealed beneath a graphic overlay and connects to the main PCB by the 8-conductor
extension of the switch layer, referred to as the "keytail". The serial port connector (DB-9) is mounted
to the rear panel and connects to the main PCB with a 4-conductor cable and SIP (single in-line pin)
header.
The photometer assembly connects to the main PCB via a 14-conductor ribbon cable and DIP plug
as well as a 10-conductor rainbow ribbon cable and double row header. The incubation block
connects to the main PCB via a 4-conductor cable and SIP header. The 12VDC cooling fan is
mounted to the chassis base and connects to the main PCB via a 2-conductor cable and SIP header.
All AC mains components are mounted on the chassis. Three 18 AWG wires feed 115VAC with
ground to the incubation block heat PCB. Note that the incubation block itself is tied directly to this
ground wire.
The EPROM is located beneath a hatch on the underside of the instrument to facilitate easy software
upgrades. Early models which do not incorporate the EPROM hatch require the removal of the cover
for software upgrade.
CAUTION
an additional volatile/static SRAM device 6264 (8K bytes volatile) may be used in
conjunction with a 48T08 RAM device in some instruments
• PCB revisions–installed components, locations, and jumpers. Refer to the appropriate PCB
layout in the “PCB Layouts” section of this manual.
Paper roll
cover
Incubation
block
Read well
Printer
Display
Keypad
CAUTION
OFF
ON
POWER
Fan Power
transformer
Fuse block
Main PCB
Incubation block
J8
Filter wheel motor (test points)
EPROM
(underneath main PCB)
Lamp
Photometer
Cover Cover
screw screw
Calibration trim- Incubation block
pot hatch screws
Cover Cover
screw screw
Photometer screws
EPROM hatch
Cover
Front of instrument screw
Figure 4. Chassis Bottom
Principles of Operation
Photometer
The light from a tungsten-halogen lamp is passed horizontally though the tube or flowcell and the
sample it contains. The sealed box on the opposite side of the read well contains a rotating filter wheel
and photodiode. The filter wheel contains optical bandpass filters at various wavelengths, and is
speed controlled, via drivers U9A and U9B in parallel, to approximately 4 rps under software control.
As each filter passes in front of the photodetector, an infrared optical switch generates a pulse (FCNT)
at U13. C14 charges to the peak voltage produced by the photodetector and amplifiers U16 and U14B.
The sampled voltage is buffered by U15A and then fed to comparator U15B which compares the
sampled voltage to the output of an exponential capacitor decay circuit built around Q3 and C16. The
positive voltage at the comparator output enables a counter in 8254 timer U4. The photodetector
output is proportional to the intensity of the light, whereas the width of the positive phase of the
comparator output is proportional to the absorbance. An oscilloscope can be used to view the
important signals at connector J8 while the instrument is in operation. See Figure 5, Oscilloscope
Waveforms.
Temperature control
The incubation block and read well are maintained at 37½C. Thermistors (10k @25½C) mounted in
the incubation block and in the read well measure the temperature. These thermistors are multiplexed
at a 0.5 second rate into the feedback path of oscillator U14A. The waveform at pin 1 is a sawtooth
of approximately 1.2 Vpp amplitude centered at +2.5 V. Schmitt triggers U11 convert this to a square
wave for current reversal and to drive the CLK2 input of U4. The microprocessor heats the system
to maintain the frequency of this signal at 2.08 kHz, the 37½C set point.
Power resistors located on the bottom of the incubation block are switched to 115VAC via an
optotriac which is driven by U9C. A red LED located on the block heat PCB illuminates when block
heat is on, and a red LED located on the main PCB illuminates when cell heat is on. For the read well,
driver U10 applies 12VDC (raw) across heater resistors located on the cell heat PCB.
WARNING
CAUTION
Do not make any hardware adjustments until you have read the
section "Calibration".
START
Verify power cable connected.
Verify voltage select switch setting.
Verify printer papr installed.
YES
YES
YES YES NO YES
YES Replace lamp.
Figure 5. Troubleshooting
Check conn pins at J9
All voltages YES
Check signal at J8-5 Replace filters with NO
Check U14 and U15
NO
Instrument is
for use by authorized personnel and is to be used for the sole purpose of providing routine instrument maintenance and repair services.
© 1994 - 1997 Awareness Technology, Inc. Unauthorized duplication is strictly prohibited. Information given in this manual is restricted
Rev. D
Rev. D 9
Troubleshooting
The flowchart in Figure 5 describes the logical steps to take if the instrument is malfunctioning. It
is only a guide to troubleshooting, and is intended to assist in determining problems which are routine.
It is not intended to take the place of an experienced technician, nor does it attempt to cover all
possible problems. Note, for example, that the temperature control system is not covered.
In the following section, each subassembly or component group and possible problems and solutions
are outlined.
Power Supply
The power supply consists of a transformer, two diode bridges, and three regulators. Line voltage
supplied to the transformer is converted to 36 VAC, center tapped, which feeds diode bridge BR2.
The center tap is used as a reference for regulators VR4 and VR5, which provide +15 VDC and -15
VDC for analog circuitry. Another transformer output supplies 11VAC to diode bridge BR1, which
in turn provides +12 VDC (raw, 11-13 VDC nominal) to the system, and VR3 regulates this down
to +5 VDC for the logic and other low voltage control circuits.
WARNING
A "dead" instrument may be caused by just a blown fuse. However, a blown fuse may indicate a
problem on the main PCB or transformer. Also, the voltage select switch setting must match the line
voltage. If there is no input voltage present at J6, check the fuse. To replace the fuse, disconnect the
power cable and open the instrument. Locate the double clip fuse holder mounted on the inside of
the rear panel. Locate the blown fuse and remove it with a fuse puller, or carefully pry it out with a
small screwdriver. Install two (2) 0.6 A 3AG slow-blow fuse. Replace only with fuse of the specified
type and current ratings.
If voltage is present at J6, check for input voltage on VR3, VR4, and VR5. If no voltage is present,
the diode bridge BR1 or BR2 may have failed.
Photometer
The photometer assembly can be examined as several component systems:
The read well assembly serves to hold the tube centered on the cell block, between a fixed plate and
a spring loaded plate. A microswitch mounted to the cell heat PCB operates when a tube is inserted.
The filter wheel turns on a shoulder screw shaft and is driven by the filter wheel motor via a neoprene
belt. The filter wheel itself requires no adjustments.
The rotation of the photometer filter wheel is under micro-processor control. The processor turns the
wheel on and off and maintains it rotating at a constant average speed. If the processor fails to detect
motion of the wheel within 7 seconds of the command to start, the “Filter Wheel Err” message occurs.
Possiblecauses:
The belt has come off the wheel.
The motor does not respond to drive circuit.
The drive circuit and or connections are missing or defective.
The wheel detection circuit connections are missing or faulty.
Analysis process:
Note: In general the wheel only rotates while the instrument is in a reading mode and the lamp is on.
Remove the instrument cover per the cover removal procedure.
Check that the photometer cable J9 (blue) and the rainbow cable J5 are seated.
Turn the unit on. Measure 5-6 volts at the yellow wire of the filter wheel motor.
Ground the brown wire-the motor should rotate at a rapid rate.
Confirm that the filter count pulses appear at test points J8#2.
In a reading mode, check that pin# 1 of U9, ULN2003, is high (motor on) or pulsing.
Check that U9 pin #16 is low or pulsing.
The photometer PCB contains a photodiode, a very sensitive opamp circuit (U16) and phototransistors
Q7 and Q8. Because the photodetector and related circuitry is solid-state, it should require no service.
Avoid unnecessary handling of the photometer PCB or removal of the optical cover.
The lamp is intended to be maintenance free for the life of the instrument, since the lamp is turned
off automatically after 30 minutes of instrument inactivity. Under heavy usage the lamp remains on
for longer periods and so may require replacement. Also, a physical shock to the instrument could
cause filament breakage. The lamp must be replaced if output becomes low or the lamp fails
completely. To check for low or no lamp output, insert a borosilicate tube filled with plain water into
the read well. Do not use a soda-lime glass tube, since it does not transmit at 340 nm. Select test #186.
The instrument prints the wavelength, position, and the detected voltage for each filter. The voltages
should be between 2 and 10 volts. If all of the voltages are below 2.0 volts, the lamp is the likely
suspect. As a final check, measure the voltage at the lamp terminals. If the lamp voltage is much lower
than 4.5 VDC, the regulator circuitry on the main PCB (Q6 and VR1) may be the problem. Otherwise,
replace the lamp. Refer to the section “Lamp Replacement”.
If only one or two filters report low detected voltages, degraded filters or a misadjusted lamp may
be the cause. To check for misadjusted lamp, refer to Figures 7 and 8, as well as the procedure “Lamp
Replacement”. The optical interference filters contained in the wheel are of metal-deposition type
construction and are intended to be maintenance free for the life of the instrument. Some older
instruments incorporated emulsion-type filters whose transmittance can be reduced dramatically if
subjected to high humidity over very long periods. Refer to the section “Filter Replacement”.
1900 Series Service Manual
© 1994 - 1997 Awareness Technology, Inc. Unauthorized duplication is strictly prohibited. Information given in this manual is restricted
for use by authorized personnel and is to be used for the sole purpose of providing routine instrument maintenance and repair services.
Rev. D 11
Temperature Control
The temperature control system is very stable and ordinarily does not require adjustment or
recalibration. In the event calibration must be verified or reestablished, refer to the section
"Calibration". Be sure to read the entire section on calibration before attempting any adjustments.
Main PCB
Under normal circumstances, there are no adjustments to be made to the main PCB. Circuit failures
are highly unlikely, but if they occur, it is recommended that the repairs be performed by factory
authorized technicians. There are ten test points on J8 which provide access to a number of vital
signals. The instrument can be observed in operation with an oscilloscope. Typical test point
waveforms are shown in Figure 6.
Internal Printer
The internal printer is a 20 column thermal type device which prints ASCII characters using a 5 x 7
dot matrix. (Graphics printers use a 5 x 8 dot matrix, with the extra bit used only in graphics mode.)
A printer PCB, incorporating a microcontroller, manages the print head motor and the head drivers.
There are no adjustments, and service is limited to replacement of the entire printer mechanism. A
printer jam can occur if the printer paper tears and becomes lodged in the printer mechanism, thus
preventing the print head from moving freely. Refer to the section "Printer Jams".
Display
The display should be clearly legible with no missing or dim characters or segments. There are no
adjustments, and service is limited to replacement.
Keypad
The keypad is a sealed membrane switch layer which is serviceable only by replacement. You can
test the keypad by pressing AUX, then pressing all keys except CLEAR and ENTER. Note that each
key causes the instrument to beep and display a character. Press CLEAR and the display clears. Press
ENTER to end the test.
Serial Port
The serial port is intended for use with either the aspirating flowcell accessory or with an external
serial printer. Early models only support a serial printer. By using a special cable, a serial printer or
computer with a serial port may be connected. The port is a female 9-pin DB-style connector using
RS-232 signals in a nonstandard pinout. The data format is 2400 baud, 8 bits, 1 stop bit, and no parity.
There are two different pinouts for the serial port:
Error Messages
Error messages are displayed to inform the user of a possible problem. They are intended to help the
operator locate the problem. If error messages appear frequently, the most likely cause will be a
hardware problem.
LAMP FAILURE The lamp does not appear to illuminated at all. Low voltages
were detected for all filter positions. See the section "Photom-
eter" under "Troubleshooting".
PRINTER PAPER JAM The internal printer paper path is obstructed. Clear the paper
path. If the paper path is clear, Check the 14-pin DIP cable
connecting the printer PCB to the main PCB.
FILTER WHEEL ERR The instrument cannot detect pulses from the filter wheel. Check
for rotation of the filter wheel as a dislodged or broken drive belt
will prevent the filter wheel from turning. Check for signal at J8-
2. Check the photometer LED board and the phototransistors Q7
and Q8 on the photometer PCB. See the section "Photometer"
under "Troubleshooting".
The following error messages indicate possible failure of the NV RAM U3. U3 can be checked by
substitution.
MEMORY ERROR The checksum failed when a stored test was recalled. The test
was deleted.
WATER VALUES RESET The stored water absorbances were corrupted or not found.
DO TEMP SET TEST 210! The stored temperature calibration values were corrupted or not
found. See the section "Restore Calibration Data".
DO ABS SET TEST 212! The stored absorbance calibration values were corrupted or not
found. See the section "Restore Calibration Data".
ServiceProcedures
Opening the Instrument
The cover must be removed to allow access to the inside of the instrument. Disconnect the power
cable and the serial cable (if connected) from the rear panel. Invert the instrument on a soft
nonabrasive padded surface such as a terrycloth towel, to prevent scratching. Refer to Figure 4,
Chassis Bottom. Locate and remove the (5) cover screws from the bottom of the instrument. Do not
remove or loosen any other screws. While holding the instrument cover in place with both hands,
return the instrument to the upright position.
On some models, the printer mechanism is mounted to the main PCB and the printer paper roll must
be removed to allow cover removal. Press inward on the sides of the paper roll cover and lift it off.
Lift out the paper roll and tear off the paper where it enters the printer mechanism.
Grasp the cover at the left side. Gently lift the cover upward and to the right, until the cabling is visible.
You can rest the cover on its side while you disconnect the cables. Refer to Figure 7, Cover
Connections. Disconnect the display cable at the left front of the main PCB assembly. Place a
screwdriver between the 14-pin DIP plug and its socket and pry gently upwards. Do not bend the pins.
Disconnect the printer cable in the same way. Disconnect the keypad cable from its connector.
To reinstall the cover, reverse the procedure. Position the cover on its side to the right of the chassis
base. Connect the printer, display, and keyboard cables. Carefully fit the cover to the chassis base.
Install the cover screws. Do not overtighten the cover screws.
WARNING
To display
To printer
To keypad
Main PCB
Red stripe
Red stripe
Lamp Replacement
The lamp should be replaced only if it fails to light, or several filter voltages are reported as low.
Procedure:
1. If using the flowcell accessory, remove the flowcell and place the instrument in tube mode.
2. Set the power switch to OFF (O). Open the instrument. Locate the photometer and the lamp
at the left side of the photometer. Refer to Figure 8, Lamp Replacement.
CAUTION
3. Loosen but do not remove the lamp terminal screws. Do not loosen or remove any other
screws. Remove the lamp by lifting it upward out of the connector.
4. Use a pair of pliers or tweezers to handle the new lamp. Do not handle with bare skin.
Insert the lamp leads into the connector until they bottom out. The lamp filament must
be centered on the lens and the lamp body must be parallel with the lamp bracket.
While holding the lamp in alignment, tighten the lamp terminal screws. You should be
able to visually confirm the lamp alignment by sighting through the lamp and lens to
view the aperture on the spring plate behind the lens. All three elements should be
aligned. With the newer lamp bracket (Figure 8a), you can adjust the height of the lamp
using the indicated screw to raise or lower the plate height.
5. Set the power switch to ON. Shield your eyes from the lamp beam and observe the
projection of the beam onto the aperture. Refer to Figure 9, Spot Alignment. The spot
should be small and centered on the aperture. The spot should be sufficiently large to
just encircle the aperture. If the spot is not centered, repeat step 4.
6. Insert a borosilicate tube filled with plain water into the read well. Do not use a soda-
lime glass tube, since it does not transmit at 340 nm. Select test #186. The instrument
prints the detected voltage for each filter position. All voltages should be between 2.00
volts and 10.00 volts. If all the voltages report low, repeat step 5 until optimum lamp
position is obtained.
Lens Aperture
Spring plate
Lamp terminal Lamp filament must be centered
screws vertically and horizontally on lens.
Figure 8. Lamp Replacement
Use screw to
adjust height
of lamp.
2. Use a pencil to mark the front and side edges of the photometer on the chassis so that the
photometer can be installed in its original position.
3. Locate the (3) #6 screws holding the photometer assembly to the chassis. From the bottom of the
instrument, remove these screws and washers while noting the screw lengths and locations from
which they were removed.
4. Refer to Figure 10, Filter Replacement. Remove the four 6-32 screws retaining the photometer
cover. Set the photometer cover aside.
5. Remove the two 4-40 screws securing the photometer PCB. Gently move the PCB aside without
disconnecting any wires.
6. Remove the belt from the filter wheel and pulley. Loosen the shaft (shoulder screw). Remove the
shaft and filter wheel. Note the number of nylon washers and the order of installation.
WARNING
Retaining Rings (used on later production filter wheels) will pop
out from filter wheel when its spring tension is released during
removal. Shield the opening with hand and wear safety glasses.
7. Refer to Figure 11. Locate the filter to be removed. There are currently two means of filter retention
in field use; silicone glue or a Retaining Ring. Refer to Figure 10 and determine if a Retaining Ring
is used. If a Retaining Ring is used, carefully pry two to three of the retaining ring teeth away from
the filter until the ring is dislodged and remove the ring and filter. If silicone glue is present, remove
the silicone and push the filter out of the wheel using the eraser end of a pencil or other soft blunt
object and the glue should release. Remove any remaining filter components from that position in
the wheel.
8. Locate the neutral density filters, dot screen, and transmittance filters that were included with the
replacement filter and drop them first into the cavity. Install the interference filter with the mirror
side down. Place the replacement retainer over the filter so that the tabs are angled away from the
filter and press in place with a 7/16 diameter wooden dowel or similar object.
9. Install the filter wheel taking care not to pinch washers under the shaft. Reassemble the shaft and
washers as disassembled. Tighten the shaft securely. The filter wheel should spin freely.
10. Install the filter wheel belt. Be sure that the belt is centered on the filter wheel and is not twisted.
11. Install the photometer PCB taking care to center the board around the shaft.
12. Replace the photometer cover, taking care to position the cable in the slot of the cover. Do not pinch
the cable under the cover. Tighten cover screws only until snug. Do not overtighten the photometer
cover screws! Doing so will bend the photometer cover and create light leakage.
1900 Series Service Manual
© 1994 - 1997 Awareness Technology, Inc. Unauthorized duplication is strictly prohibited. Information given in this manual is restricted
for use by authorized personnel and is to be used for the sole purpose of providing routine instrument maintenance and repair services.
Rev. D 19
13. Install the photometer subassembly to the chassis by replacing the (3) #6 self tap screws through
the chassis base in their original locations. Line up photometer with locating marks made in step
2. Connect the (2) cables removed in step 1.
14. Attach the power cord and connect the instrument to the mains supply. Set the power switch to ON
(1). Insert a borosilicate tube filled with plain water into the read well. Do not use a soda-lime glass
tube, since it does not transmit at 340 nm. Select test #186. The instrument prints the detected
voltage for each filters. All voltages should now be between 2 and 10 volts. If not, check lamp
alignment. If the lamp alignment is properly set, the neutral density filters may need to be changed.
Add neutrals to lower the voltage. Remove neutrals to increase the voltage.
Filter wheel
Belt
Remove glue or
retainer and push
Shoulder out filter with blunt
screw Remove filter wheel. object.
Filter Label
The filter label located on the photometer cover describes the specific filter wheel configuration for
your particular instrument. Filter wheel position is the physical placement of the filter on the wheel.
The filter wheel position numbers are shown in Figure 11. Note the position of the Index hole and
the Home hole.
Each filter position can have several filter elements installed. The four-digit filter wheel number
identifies the filter wheel batch, including filter lot codes, dot screens, neutral density filters, and
assembly date for that particular manufacturing lot of filter wheels. Some earlier filter label styles
may include this individual information. If you require specific information for a filter wheel number,
contact the manufacturer.
4 Position 6 Position
Rotation Rotation
6 1
4 1
5 2
Home
3 hole 2
4 Home Index 3
Index hole
hole hole
Printer Jams
CAUTION
If the instrument displays “Printer is jammed!”, or if the print head does not return to the home
position, check for obstructions in the print head path. Refer to Figure 12, Clearing printer jams.
Carefully remove any paper or debris with a pair of tweezers. Turn off the power switch, wait 5
seconds, then turn on the power switch. The print head should move to the right side and then return
to home position at the left.
An alternate method of removing a particularly stubborn wad of paper is to move the print head
manually. To do this, open the instrument. Remove the two nuts holding the printer bracket to the
cover. View the front of the printer mechanism. Locate the small gear on the right side which turns
the grooved steel print head shaft. Turn the gear so that the print head moves away from paper wad
and the paper can be easily removed.
Home
position
Print head is jammed
against wad of paper
Printer Repairs
A graphics capable printer has been introduced in recent instruments. Replacement printers are
graphics capable and can be made compatible with earlier non graphics capable printer PCBs. One
way to identify which type of printer is used is to remove the ribbon cable from the keytail socket
on the printer interface PCB. Look at the connector on the ribbon cable. An earlier non graphics
capable printer will have eight conductors. The graphics capable printer will have nine. Another way
to identify which printer is used is to look at the blue inspection label on the printer interface PCB.
If the number on the label is M020445 or higher, a graphics capable printer is used. Repairs to printer
mechanisms can consist of print head replacement or printer mechanism replacement.
1. Pry out the pin (1) which holds the gear (2) in place.
2. Remove the pin (3) from the side of the print head with tweezers and pry the pin (4) from
the top of the Print Head. The Print Head should now be free to move along the Drive Screw
(6).
3. Remove the snap ring (5) from the end of the drive screw (6) and withdraw the drive screw
and gear assembly from the printer mechanism in the direction shown.
4. Press the end of the slider rod (7) out of the hole in the printer mechanism in the direction
shown from the left side of the mechanism. It is not necessary to remove the slider rod
completely from the mechanism.
5. Slide the Print Head off the slider rod and replace with the new Print Head. Reassemble the
mechanism in reverse order of the above disassembly steps.
1900 Series Service Manual
© 1994 - 1997 Awareness Technology, Inc. Unauthorized duplication is strictly prohibited. Information given in this manual is restricted
for use by authorized personnel and is to be used for the sole purpose of providing routine instrument maintenance and repair services.
Rev. D 23
2
RIGHT SIDE
3
4
7 5
LEFT SIDE
2. Move the Print Head to the right-most position as shown by rotating the Screw Drive with
its drive gear on the right side of the mechanism.
4. Install the new platen so that the end which has the longer pin is oriented toward the right
side of the mechanism. Insert the right end of the platen under the print head. Use a pen point
or similar blunt instrument to push metal spring slightly forward, then slip the left side of
platen in place.
Dress Cover
RIGHT
SIDE
Platen
(darkened area)
Print Head
Screw Drive
LEFT
SIDE
The key feature to look for on the Main PCB is the J17 connector (Figure 17B). The replacement
Main PCB will have J17.
Photometers are connected with either 2 or 3 cables depending on the configuration. The key feature
to look for on the Photometer is whether or not the lamp socket is wired with yellow wires (referred
to as a “3-Cable Photometer”). The replacement photometer will be a 3-Cable photometer with the
yellow wires.
Refer to Table I and Figures 17A and 17B below to determine if an adaptor will be needed to insure
compatibility.
Photometer Replacement.
1. Open the instrument as described in “Opening the instrument”. Refer to Figure 3. Locate the
photometer. Note positioning of the cables leading from the photometer to the main PCB and
unplug the cables from the main PCB.
2. Mark the perimeter of the photometer on the chassis with a pencil so the replacement
photometer can be properly positioned.
3. Locate the (3) #6 screws holding the photometer assembly to the chassis. From the bottom
of the instrument, remove these screws, washers, and the speed nuts from inside the
instrument while noting the screw lengths and the locations from which they were removed.
4. Install the replacement photometer subassembly to the chassis by replacing the (3) #6 self
tap screws in their original locations. Insure that internal tooth lock washers are installed
between the screw heads and the chassis base. Line up photometer with locating marks made
in step 2. Connect the cables removed in step 1.
NOTE
The internal tooth lock washer must make electrical contact (ground)
with the chassis base for low noise operation.
1. Open the instrument as described in "Opening the instrument". Refer to Figure 3. Locate the
Main PCB. Unplug cables from the main PCB and disconnect the wires from the trans-
former.
2. Refer to Figure 18. Remove the two screws securing the Main PCB. Apply Thermal
Compound supplied with the replacement PCB to area between the heat sink on the PCB and
the chassis as shown in Figure 18. Secure the replacement PCB in the same fashion as the
removed PCB.
3. Reconnect transformer wires. See “Block Diagram” section of this manual for proper wire
connections. Plug in all remaining cables.
#4 NUT
MAIN PCB #4 INTERNAL
TOOTH LOCK WASHER
NOTE
The internal tooth lock washer must make electrical contact (ground)
with the chassis base for low noise operation.
Calibration
Each instrument is calibrated during manufacturing using standards that are traceable to the National
Institute for Standards and Testing (NIST), and is tested to verify its linearity to 2A. This preset
calibration is very stable. Absolute calibration can be verified with the use of NIST filters, or by
comparison to a reference instrument that is known to be calibrated to NIST filters. Calibration may
be confirmed using a commercially available calibration check set which can be obtained from your
distributor. A periodic verification of instrument accuracy and linearity is advised. Since most lab
test results are based upon standards rather than upon absolute absorbances, the linearity of the
instrument, rather than the accuracy, is the more critical indicator of instrument performance.
Standards and blanks should be closely checked for accuracy and results should be compared with
a reference instrument. Use of a commercially available photometer check set to verify photometric
accuracy and linearity is strongly recommended. If field recalibration is needed, it should only be
performed with the proper reference materials and instruments.
All instruments manufactured before June 1993 utilize hardware calibration. This requires
making adjustments to the trimpots for absorbance gain and offset, and temperature offset.
To determine whether the instrument incorporates software calibration features, select test # 213. If
calibration data is printed, the instrument supports software calibration. Refer to the section
"Software Calibration". If no calibration data is printed, refer to the section "Hardware Calibration".
In either case, if the trimpots have been disturbed or components C16, R12, R16, R11, R13, RN8,
R24, U16, or the photodiode have been replaced, the instrument will require hardware calibration.
CAUTION
Softwarecalibrationshouldalwaysbeattemptedbeforeresorting
to hardware calibration.
Software Calibration
Calibration data are entered at the keypad and are stored in nonvolatile memory with a checksum that
is recalculated and compared each time the instrument is powered on, a new software mode is
selected, or a stored test is recalled. Failure to recover the calibration data properly (checksum failure)
will be indicated on the display and the internal printer:
If either of these messages are printed or displayed, it indicates that the calibration values have been
lost. These messages will be printed each time the checksum failure occurs and until calibration is
performed. The instrument also annunciates this condition with multiple beeps.
The absorbance calibration data is stored as a scaling factor, which is the ratio of a known reference
absorbance to the instrument's reported absorbance. The value entered at the keypad is multiplied by
the stored value to obtain a new scaling factor.
The temperature calibration data is stored as offsets which the instrument adds to the sensed
temperatures. The value entered at the keypad is added to the stored offset to produce a net
adjustment. Separate offsets are maintained for the incubation block and the read well.
The calibration data may be printed at any time by selecting test #213. This prints the serial number
of the instrument, the date of last calibration, the stored calibration data: the absorbance scaling
factor, the net block temperature offset, and the net cell temperature offset.
In the event of calibration data loss, the temperature offsets for both the incubation block and the read
well are set to 0.0 and the absorbance scaling factor is set to 1.000. In this condition, the maximum
temperature error is ±1.5 ½C and the maximum absorbance error is ±10%, provided the trimpots have
not been disturbed. The calibration data can be restored as described below.
To recalibrate the instrument, refer to the sections "Software Calibration – Temperature" and
"Software Calibration – Absorbance".
Procedure:
1. Select test #213 to print the calibration data. Verify that the data is as follows:
2. If the data printed in step 1 did not match the example, stop. Complete the procedure "Reset
Calibration Data", then repeat this procedure. Otherwise, locate the calibration data label
on the underside of the instrument. Copy the data from the label for reference in the
following steps.
3. If the date and time are incorrect, set the date and time as described in the Owner's Manual.
BLOCK=
Enter the value from the Block Temp line on the calibration label.
CELL=
Enter the data from the Cell Temp line of the calibration label.
ABS FACTOR=
Enter the number from the Abs Factor line of the calibration label.
7. Select test #213 to print the calibration data. The printed data should now match the values
shown on the calibration data label. If it does not, complete the procedure "Reset
Calibration Data", then repeat this procedure.
Procedure:
1. Select test #213 to print the calibration data. Verify that the printed data is as follows:
2. If the data printed in step 1 matches the example shown, stop. The calibration data is already
reset. If the data printed in step 1 matches the data shown on the calibration data label on
the bottom of the instrument, and you do not wish to alter the calibration, stop. Otherwise,
make a note of the values printed in step 1.
BLOCK=
Enter the negative of the value printed for BLOCK TEMP. This will reset the block
temperature offset to 0.0.
CELL=
Enter the negative of the value that was printed for CELL TEMP. This will reset the cell
temperature offset to 0.0.
ABS FACTOR=
Enter the inverse of the value printed for ABS FACTOR in step 1. That is, calculate
1
ABS FACTOR
6. Select test #213 to print the calibration data. The printed data should now match the
example in step 1. If not, repeat this procedure.
Note that precision thermistor probes are used. Do not use a thermometer. A typical mercury bulb
or other glass thermometer adds a great deal of thermal mass to the system, as well as provides a
conduction path for heat, thereby frustrating the instrument's heating capability.
Procedure:
1. Complete the procedure "Reset Calibration Data".
2. Place a tube or cuvette filled with 1 ml of water into the incubation block. Immerse the
thermistor probe in the approximate center of the tube. Place a similar arrangement in the
read well. Select test #188 to extend the lamp time.
4. If the DMM being used is not autoscaling, set it so that 20Ký is in range. Zero the meter and
then read the resistance of the thermistors. If the resistance is between 17994 ý and 18435
ý, no adjustments are needed. Otherwise, continue to the next step.
T = R - 18210
C
Where:
R is the measured resistance.
C is equal to 750 if the measured resistance is greater than 18210.
C is equal to 720 if the measured resistance is less than 18210.
BLOCK=
Type the offset calculated above for the block and press ENTER.
CELL=
Type the offset calculated for the cell and press ENTER.
8. Repeat steps 3 through 6 until the resistance is within the specified range and the displayed
temperature is 37°C ± 0.3. Select test #213 each time to print the current net adjustments. The
1900 Series Service Manual
© 1994 - 1997 Awareness Technology, Inc. Unauthorized duplication is strictly prohibited. Information given in this manual is restricted
for use by authorized personnel and is to be used for the sole purpose of providing routine instrument maintenance and repair services.
36 Rev. D
net offset after the temperature is set should be ± 1.5°C or smaller.
9. When you are done, select test #213 to print the new calibration data. Enter these values on
the calibration data label on the bottom of the instrument.
2. Place a borosilicate tube filled with plain water into the read well. Do not use a soda-lime
glass tube, since it does not transmit at 340 nm.
3. Select test #186 and confirm that all of the detected filter voltages are between 2.00 and
10.00 volts.
4. Determine the absorbance of both the 1:1 reference material and the 1:2 dilution on a
reference spectrophotometer. The 1:2 dilution should be in the range of .8 to 1.2 absorbance.
The 1:1 material should be in the range of 1.6 to 2.4 absorbance.
5. Select the absorbance mode (Press ABS). Select the required wavelengths. Select 0 for no
differential filter. Blank on the same diluent material used to prepare the concentrations.
6. Read the 1:2 dilution. Divide the absorbance as read on the reference spectrophotometer by
the reported absorbance value. Note the result of this calculation for the next step.
7. Exit the absorbance mode and select test #212. The display shows
ABS FACTOR=
Enter the result of the calculation performed in the preceding step. When this factor is
entered the instrument will multiply by the old factor and display a net factor (the new
calibration data).
8. Select the absorbance mode again. Blank as before on the diluent. The 1:2 dilution
absorbance should now agree with the reference to within ±.005 absorbance.
9. Read the 1:1 concentration. It should agree within ±2 % of the reference. If necessary,
carefully adjust trimpot TP3 to achieve this agreement. Read the section “Hardware
Calibration” before making any adjustments. Re-blank and reconfirm the values. Refer to
Figures 19 and 20 for trimpot locations.
10. When you are done, select test #213 to print the new calibration data. Enter these values on
the calibration data label on the bottom of the instrument.
1900 Series Service Manual
© 1994 - 1997 Awareness Technology, Inc. Unauthorized duplication is strictly prohibited. Information given in this manual is restricted
for use by authorized personnel and is to be used for the sole purpose of providing routine instrument maintenance and repair services.
Rev. D 37
Hardware Calibration
CAUTION
Note that precision thermistor probes are used. Do not use a thermometer. A typical mercury bulb
or other glass thermometer adds a great deal of thermal mass to the system, as well as provides a
conduction path for heat, thereby frustrating the instrument's heating capability.
Procedure:
1. Place a tube (or cuvette) filled with 1 ml of water into the incubation block. Suspend the
reference thermistor probe in the approximate center of the tube. Do not allow the probe tip
to touch the tube wall. Place a similar arrangement into the cell.
2. Press the LAMP key to turn on the lamp. Allow 15 minutes for equilibration.
3. Set the DMM to read 20K. Read the resistance of the thermistors. If the resistance is
between 17994 ý and 18435 ý, no adjustments are needed. Otherwise, continue to the next
step.
4. Refer to Figures 19 and 20. Adjust the trimpot(s) by a small amount. Turn it clockwise to
lower the temperature; counterclockwise to raise the temperature. TP4 adjusts the cell
temperature; TP1 adjusts the incubation block temperature.
5. Repeat steps 2 through 4 until the resistances of the probes are within range. You should
attempt to get the resistance to read as close to 18210 ý as possible.
Front of
instrument
Hatch
TP1
Block Temp
TP2
Abs Gain TP4
Cell Temp
TP3
Abs Offset
TP3 TP4
Abs Offset Cell Temp
TP2 TP1
Abs Gain Block Temp
Front of instrument
Procedure:
1. Place a borosilicate tube filled with plain water into the read well. Do not use a soda-lime
glass tube, since it does not transmit at 340 nm.
2. Select test #186 and confirm that all of the detected filter voltages are between 2.0 and 10.0
volts. If the voltages are out of range, refer to the section “Troubleshooting”,
3. Determine the absorbance of both the 1:1 material and the 1:2 dilution monochromatically
on a reference spectrophotometer. The 1:2 dilution should be in the range of .8 to 1.2
absorbance. The 1:1 material should be in the range of 1.6 to 2.4 absorbance. Note the
absorbance values reported by the reference instrument.
4. Press ABS to place the instrument into the absorbance mode. Select the required primary
wavelength. Select 0 for the differential wavelength (monochromatic). Blank on the same
diluent material used to prepare the concentrations.
5. Read the 1:2 dilution. The reported absorbance should agree within 1% ± .005 of the
reference. If not, adjust trimpot TP2 a small amount – clockwise to raise the value,
counterclockwise to lower the value. Repeat this step as needed until the reported
absorbance is within limits.
6. Read the 1:1 concentration. The reported absorbance should agree within 2% ± .005 of the
reference. If not, adjust trimpot TP3 a small amount – clockwise to increase the value,
counterclockwise to reduce the value. Repeat this step as needed until the reported
absorbance is within limits.
7. Repeat steps 2 through 7 until all three criteria are met.: filter voltages, low absorbance
(gain), and high absorbance (offset).
Replacement Parts
ConsumableItemsandAccessories
Lamp .......................................................................................................................112004
Fuses (set of 2) ..........................................................................................................102002
Printer paper (5 rolls) .................................................................................................150001
Carrying Case ...........................................................................................................000390
12x75 mm borosilicate tubes (250/box, 1000/case) .......................................................157302
Dust Cover ...............................................................................................................001990
Nonconsumable Items*
Keypad (flat) .............................................................................................................183103
Keypad (domed) ........................................................................................................183113
Keypad/overlay assembly .......................................................................................... 183354
Main PCB .................................................................................................................995003
Battery RAM chip .....................................................................................................163061
Belt, filter wheel ........................................................................................................132059
Motor, filter wheel .....................................................................................................105126
Photometerassy ............................................................................................ (specify model)
Reaction block assy ....................................................................................... (specify model)
Cover assy .................................................................................................... (specify model)
Cooling fan ...............................................................................................................104502
Internal 14-pin cable (specify length) ...........................................................................104xxx
Printer mechanism .....................................................................................................105601
Printer Platen .......................................................................................................105651
Print Head (includes printer platen) ........................................................................105652
Printer interface PCB .................................................................................................995006
Display .....................................................................................................................162519
Filter & Neutral replacement set ................................................. (specify wavelength)111XXX
* Specify the instrument serial number when ordering so that replacement part compatibility issues
canbeaddressed.
Block Diagram
PCB Layouts
Main PCB–from rev Z
Schematics
Main PCB (from rev Z) 1 of 4