2.1.1 Maintenance Routine without Dismantling the Centrifuge
2.1.1.1 Electrical Installation and Safety
• Switch OFF the centrifuge and disconnect the unit from power, check voltage supply and mains
fusing (16 Amps, slow blow characteristic)
• Check condition of plug and wall socket - replace defective parts (customer’s responsibility)
• Check cord condition and fixing / connection - replace or refit it
• Check condition of instrument socket and replace it in case of bad contacts
2.1.1.2 Location and Mechanical Inst allati on
• Check the base (ground, table, lorry with lockable wheels etc.) for resonance-free and stable
conditions
• Check for a well ventilated place and sufficient distances to walls or adjacent equipment, without
exposition to direct sunlight
• Check the leveling of the centrifuge drive with use of a spirit level
2.1.1.3 Lid Tumbler Mechanism and Safety Device
• Connect the centrifuge to power and switch ON
• Check for correct automatic lid closing and self-acting lid opening - if in disorder, readjust lid,
swivel hinges, and/or locking devices
• Check the rubber gasket for lid’s and bolt’s sealing and replace, if damaged
• For checking the electronically safety circuit: start the centrifuge, let it shortly run and stop it, the
lid must not be unlocked by the microprocessor as long as the speed is more than 60 rpm - if
safety circuit is out of function, replace main board
2.1.1.4 Cleanliness of Spin Chamber and Motor Casing
• Open the lid and remove the rotor (for loosening turn the T-handle Allen key (5mm) in arrow
direction - see rim of rotor chamber)
• Clean the spin chamber with a dry and absorbent cloth (remove all dust and moisture - see also
section for Cleaning)
• Check the cleanliness of the motor flange and take care of the annular slot around the motor shaft:
penetrating fluids can damage the upper spindle bearing or electronics, remove fluids with an
injector and/or absorbent paper
2.1.1.5 Rotor and Accessories Condition and Sealing, bellows
• Check the condition of rotors and accessory parts (especially all supporting or stressed partitions):
the rotor and/or accessory parts must not be used any longer, if there are visible traces of
mechanical damage or rust
• Check the condition of rotor and/or accessory sealing and replace them in case of malfunction
• Bellows of gas lid stays have to be greased upside down with glycerin (part no. 70902649) once a
year.
2.1.1.6 Rotor Fixing and Drive Spindle
• Check the perfect condition of the collet chuck and replace it in case of malfunction (thread is worn
out, horizontal grooves etc. )
• Check the condition of the drive cone: the centrifuge must not be used any longer, if the drive
cone is damaged (e.g. bend or it’s bearings are worn out)
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18.04.02/he/AH Page: 2 - 1
Legend RT
Multifuge 3S-R/3L-R
Service
2.1.1.7 Temperature Level (not at every unit)
• Check the wire gauze (behind the air inlet slots) left and right side for free ventilation, insufficient
air flow will lead to an inadmissible temperature rise of compressor, motor and electronic parts
2.1.1.8 Imbalance Behavior
• Install available and empty rotors and check the imbalance behaviour with rotor dependant cut off
and run through weights (see 2.5) and replace worn out motor rubber mounts, faulty main board or
sensor board
2.1.2 Maintenance Routine after Dismantling the Centrifuge Casing
2.1.2.1 Motor Supporting Elements
• Check the supporting and damping elements of the drive motor and replace them in case of
increased rubber abrasion or abundance of imbalance but at least every 3 years
2.1.2.2 Braking Circuit
• Check the function of the braking circuit (warming up of brake resistor, even and noiseless brake
effect) and replace defective parts in case of malfunction
2.1.2.3 Lead and Screwing Connections
• Check the terminal and plug connections of all leads and on all boards and electrical components,
tighten all loosen screwing connections, refit or replace defective parts
• Check the wedged connections of the board, mechanical and electrical components and re-tighten
them if necessary (use screw locking lacquer for motor mounts and lid lock assembly)
2.1.2.4 Protection Earth Core and Groundi ng Con necti ons
• Check the protection earth core for continuity and all grounding plug connectors (see also 2.7
Electrical Safety Check)
• Check isolation resistance and accessible current (see 2.7)
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18.04.02/he/AH Page: 2 - 2
Legend RT
Multifuge 3S-R/3L-R
r
2.2 Trouble Shooting
Error
Indication
Error Cause
Service
Possible Error
Source
Mains switch with
integrated fuse or
fuses on main board
Corrective Procedure
Switch on again, disconnect electric.
components success., search for other
faults
Displays
remain
dark
All display
Elements
are shortly
illuminated
Constant
No mains
voltage supply
No low voltage
supply for
indication board
Interrupted
program
CPU program
reset may be
caused by EMI
Interruption Parameter NV-RAM No or defective NV-RAM
Mains fuse or circuit
breaker failed
Faulty mains cord or
instrument socket
Faulty connection
from CPU to
indication board
Faulty indication or
CPU board
NV-RAM out of
socket or not
correctly placed
Reduced voltage
supply (<10%)
Bad or missing
ground connection
Check fuse or circuit breaker and replace o
switch on again
Check instrument cord and socket, replace
defective parts
heck connections on CPU, indication board
and connecting leads, replace defective
parts
Replace main board completely
Insert the valid NV-RAM and push it
correctly into socket
Remedy the failure if the voltage drops
often, use a voltage stabilizer
Check all ground connections and the
ground connection of all boards
Drive
makes
noises -no
good
separation
result
Lid cannot
be opened
by key at
standstill
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18.04.02/he/AH Page: 2 - 3
Mechanics
Electrical
Locking drive is
not supplied
with voltage
Latch motor Faulty motor winding Replace complete motor
Lid is not
correctly locked
wear out of motor
rubber mount
Defective terminal
connection, faulty
lead or motor winding
Faulty power electr. Replace main board
24V supply
faulty relay K2
faulty driving circuit
Lid bolt is jamming
Lid is deformed Re-adjust the lid centrally
Replace motor rubber mounts (at least
winding resistances -see test points on
Push lid centrally into lock and press the
every three years)
Check voltage on motor terminal and
main board
Check voltage for drive motor
Check switch. after power ON
Replace the main board
No or defective NV-RAM
key again
Legend RT
Multifuge 3S-R/3L-R
2.3 Error code
Error
Indication
„rotor“ in
speed
display
Error Cause
Wrong selection
of detected rotor
Service
Possible Error
Source
Inadmissible speed
or rcf value was pre-
selected
Corrective Procedure
Press start again (within 15s), else wait for
rotor standstill, lid OPEN/CLOSE, set value,
start
“bAL“
message
appears in
speed
display
“Lid“
appears in
speed
display
Imbalance run
Lid was opened
manually during
run
Protection circuit
(20V) interrupted
during run
Rotor not symmetri-
cally loaded
Base is not sturdy
enough and comes
into vibrations
Centrifuge drive is
not correctly leveled
Rotor itself has
imbalance
Drive shaft or rotor
fixing is damaged
Imbalance sensor Replace sensor board
Circuits of main
board
Forbidden
intervention
emergency opening
device must only be
used at standstill
Defective micro
switch or leads or
connectors to micro
switch are interrupted
Open lid, check rotor loading, close lid again
and restart
Change or reinforce the base (table, lorry with
lockable wheels, etc.)
Level the drive correctly by means of unit’s
feet
Rotor must no longer be used, send back to
Kendro
Replace collet chuck or motor
Replace the main board
Close lid immediately, turn power OFF/ON,
press lid down for locking, press start key,
press stop to finish run
Check leads and connectors to micro switch,
in case of a faulty micro switch, replace them
Loose plug
„OPEn“
appears in
speed
display by
supposedly
closed lid
“S-LID”
appears in
display
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18.04.02/he/AH Page: 2 - 4
20V supply for
protection circuit
is interrupted at
standstill
Sensor signal not
clear
connectors
Interrupted leads to
micro switch
Defective micro
switch
Latch not in valid
position during power
on
Check plug X20
Check leads to micro switch for continuity
Replace micro switch
Switch unit “off” and “on” again
Legend RT
Multifuge 3S-R/3L-R
Error
Indication
Error Cause
Service
Error Code
Possible Error
Source
Corrective Procedure
„E-01“
message
„E-02“
message
„E-03“
message
„E-04“
message
“E-05”
message
“E-06”
message
“E-07”
message
“E-08”
message
“E-09”
message
“E-10”
message
“E-11”
message
“E-12”
message
“E-13”
message
„E-14“
message
System clock
pulse not stable
program
sequence was
disturbed
Stack overflow
Stack underflow
Reset by HW
watchdog timer
Data lines to key
board disturbed
Display board
doesn’t match to
main board
cooled/non-
cooled
Check sum error
E-PROM
Check sum error
NV RAM
NV RAM not
initialized
NV RAM doesn’t
match E-PROM
Check sum error
NV RAM
Check sum error
NV RAM
chamber over
temperature:
display >50°C
Hardware fault on
main board
Internal Software
problem
Internal Software
problem
Internal Software
problem
Software problem No action in the field possible
Wiring display board Check wiring and connectors
Check software Replace NV RAM and CPU
E-PROM failed Replace E-PROM
NV RAM failed Replace NV RAM
Initializing of NV-RAM
is not valid
Check versions of NV
RAM and E-PROM
NV RAM failed Replace NV RAM
NV RAM failed Replace NV RAM
Compressor didn’t
work
Faulty cooling cycle Exp. valve, refrigerant loss
Change CPU, replace main board
check NV-RAM and socket, insert the correct
Check leads, terminals, start relay, capacitor,
Change main board
No action in the field possible
No action in the field possible
NV-RAM
Replace NV RAM and E-PROM
compressor
„E-15“
message
„E-16“
message
„E-17“
message
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18.04.02/he/AH Page: 2 - 5
Open temp.
sensor
Short cut temp.
sensor
wrong or faulty
rotor detection
Check sensor, control
circuits
Check sensor, control
circuits
a wrong rotor was
installed
Mains voltage failure press stop key, wait for standstill and restart
Faulty detection
circuit
wait for standstill, open the lid and install a
Replace sensor or main board
Replace sensor or main board
correct rotor
replace the main board
Legend RT
Multifuge 3S-R/3L-R
Error
Indication
„E-18“
message
„E-19“
message
Error Cause
Bucket code
not valid for this
rotor
Rotor code not
programmed
Service
Error Code
Possible Error
Source
Corrective Procedure
Not valid
Wrong rotor installed Check rotor
Interference during
recognition
Check rotor recognition board and wiring
„E-20“
message
„E-21“
message
„E-22“
message
„E-23“
message
„E-24“
message
„E-25“
message
„E-26“
message
„E-27“
message
„E-28“
message
rotor code not
valid
Recognition
disturbance
Speed signal
disturbance
Speed control
measuring
disturbance
Latch not in top
position
Time out latch
open
Time out latch
close
Signal given by
latch not valid
Wrong sense of
rotation
See E-19
wiring Check wiring
wiring Check wiring
nd
2
check was done
by rotor recognition
Check speed detection board
system
Micro switch failed,
Check micro switch adjustment, if necessary
de-adjusted, latch
Hall sensor signal not
applied
Hall sensor signal not
applied
Check latch motor and PCB
Check latch motor and PCB
Wrong identified
signal after power
“on”
After replacement of
the motor- wires
mixed
replace it
Check hall sensors
Check wiring at terminal
„E-29“
message
„E-30“
message
„E-31“
message
„E-32“
message
„E-33“
message
Motor doesn’t
turn
Control-voltage
interruption
over-
temperature
motor >150°C
Over-
temperature
Electronic
High-pressure
Cooling system
PCB faulty, see E-21,
E-22
PCB failed Replace PCB
Hot motor, no air
circulation
Faulty main board Replace main board
Faulty high pressure
switch, blocked
system
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18.04.02/he/AH Page: 2 - 6
Change PCB, rotor recognition, speed
detection, fasten motor wiring at terminal
Check motor, check grill for dust
Inspect cooling system
Legend RT
Multifuge 3S-R/3L-R
Error
Indication
Error Cause
Service
Error Code
Possible Error
Source
Corrective Procedure
„E-34“
message
„E-35“
message
„E-36“
message
„E-37“
message
„E-38“
message
„E-39“
message
„E-40“
message
„E-41“
message
Over-voltage
Over-current Main board Replace main board
NMI
interruption
Over-current
continuously
Current
measurement
disturbed
Speed control
check >n max.
Acceleration of
the unit is too
slow
Offset voltage
from the
imbalance
sensor is in a
inadmissible
area
Brake resistor,
main board
Over voltage or over-
current
Main board Replace main board
Analog signal >
hardware over current
Speed > calculated
speed
Big imbalance
Motor or main board
faulty
Imbalance sensor
faulty
Wiring from the speed
detection board to the
main board is broken
Check brake resistors, replace main board
Replace main board
Replace main board
Check speed detection board, replace the
main board
Check rotor loading, motor and main board
Replace speed detection board
Check / replace the wiring
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Legend RT
Multifuge 3S-R/3L-R
Service
2.4 Test Points
Test Points Unit Value Conditions
Mains terminal
Board resistance
Motor over-temp.
terminal
X20/B3,B4*
Over-press switch
terminal X20/P
Fans cooling plant
terminal XK
Compressor
terminal XG
terminal box
–insulation value
Speed detection
plug XW
(1 to 4)
(3 to 4)
speed
Imbalance sensor
plug XW
(1→4)
(2→4)
120V
50Ω
20V DC
20V DC
100 Ω
82 Ω
6,5 A
1,6 Ω
4,8 Ω
> 10MΩ
5V DC
4,4V
0V
n=f*30
12V DC
a(t)
All given values are related on 120 V (+/- 10%) mains voltage for
board supply
Voltage drop by one disconnected lead (error case) and linked
terminal XR
Voltage drop by one disconnected lead (error case) and linked
terminal XO
Switch OFF unit, fan resistance temperature 20°C
wire black to blue
wire brown to blue
Switch OFF unit, compressor temp. 20°C
Resistance of main coil + (starting relay 0.1Ω)
Resistance of auxiliary coil (joints 13 -> 14)
Resistance inter phase and motor casing
Board with active filter circuit
Low voltage supply
Light barrier is passed through (slot position)
Light barrier is out (turn cone a little by hand)
When centrifuge is running
Low voltage supply of sensor board
Amplitude of lateral acceleration is rotor and speed dependent,
analyzed for n > 250 rpm
Motor current I
M
cable (U,V,W)
Motor winding
resistance 20°C –
insulation value
Brake resistor
terminal XD
Rotor detection
plug XR
Temp. measuring
plug XU
3 * 7A
3 * 5,2A
3 * 3,0A
3x2,5Ω
> 10MΩ
60Ω
5V DC
0V DC
Switch OFF unit, 2 resistors parallel connected, resistance at
pulse pause lengths, this pulse mode is generated by 4 alternately
Split core transformer with Flukemeter
maximum during acceleration
Rotor #6441, set speed = 3750min
Switch OFF unit, pull off motor plugs, measure inter
U -> V, V -> W, W -> U
Resistance inter each phase and motor casing
Per rotor revolution 2 different long
pulses are separated from 2 different
Chamber temperature 20°C (PT100:
Chamber temperature -10°C (PT100:
Chamber temperature 40°C (PT100:
Edition: 04 Servicing Schedule
18.04.02/he/AH Page: 2 - 8
20°C
polarized magnets
-1
, 560W
≈
108Ω)
96Ω)
≈≈
116Ω)
Legend RT
Multifuge 3S-R/3L-R
Service
2.5 Imbalance Behaviour
• Install in table available rotor(s) in unloaded condition
Rotor/Bucket Run through
weight
75006445/75006441 20 grams 30 – 40 grams
• Insert rotor dependent cut-off weights and position them at angles of 90° to each other, the
centrifuge must stop 4 tim es indicating “bAL“ message - in case of false behaviour see trouble
shooting: no “bAL“ indicatio n.
• Insert the admissible imbalance weights in the same manner, the centrifuge must run through 4
times to maximum rotor speed.
2.6 Cleaning of Instrument Parts
ATTENTION - WARNING!
The electrical and electronic components must not be cleaned with moist detergents!
For Cleaning the centrifuge housing or its accessories see Operating Instructions section 1
(maintenance and care).
• Electronic components
Clean dusty components carefully with a dry and soft brush and remove loose dust with a
vacuum cleaner.
• Fans
Scratch off car efully with a knife or similar tool the cr usted dirt from the fans ’ blades. Resulting
grooves or marks must be removed subsequently with a fine abrasive cloth. Loose dirt is to
remove with an absorbent cloth or vacuum cleaner.
• Vent holes
Remove dirt from the vent grid behind the front panel by using a brush and vacuum cleaner.
• Condensers of cooling plant (if available)
The louvers between the c ondensers’ heat air deflect ors have to be vacuum c leaned. In case of
persistent dirt the unit must be carried to an appropriate place where the condensers can be
cleaned with compressed air from inside to outside. Bended heat air deflectors have to be
realigned correctly.
Cut off weight
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Legend RT
Multifuge 3S-R/3L-R
Service
2.7 Electrical Safety Check
ATTENTION!
A final electrical safety check must be performed after each maintenance and/or repair!
• Resistance check of protective conductor
The measuring value of the resistance between the mains plug's grounding pin and the
grounding conductors of the motor, electronic chassis and the casing must not exceed 200 mΩ.
• Insulation resistance Check
Check also the insulation resistance between the poles of the mains plug and the grounding
conductor; the resistance value must be more than 2 MΩ.
• Accessible current measured to EN 61 010
The accessible current must not exceed 3.5 mAmps in single fault condition (interrupted
protection earth wire)! In accordance with the EN61010, IEC1010 and UL3101 such a fault
condition can be reproduced by the following measuring circuit.
Steckergehäus e / plug-in casing
L (N)
N (L)
PE
500
±1%
Ω
0,22µF
±5%
Ω
Körperstrom:
accessible current:
U = 1750mV I = 3,5mA
10k
±5%
0,022µF
±5%
I [mA] = U [mV] / 500 :
maxmax
≡
Spezifaktionen für Meßgerät
- TRMS, DC - 5kHz oder mehr
- Eingangswiderstan d > 1M
- Toleranz 5% oder besser
- Crest Faktor 5 oder besser
V
AC
Specifaction for the meter
- TRMS, DC - 5kHz or more
- Input resistance > 1M
- Tolerance 5% or better
- Crest Factor 5 or better
Ω
Ω
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Legend RT
Multifuge 3S-R/3L-R
3 Functional Description
3.1 Block Functions
The Multifuge 3L-R/3S-R, Legend RT is a refrigerated microprocessor controlled laboratory
tabletop centrifuge with noise reduced induction drive motor incorporating automatic rotor and
imbalance detection and self-closing door locking systems.
The unit is equipped with following boards and components (block diagram 4-1):
• Instrument socket for mains cable at the back
• Two poles mains switch
• Main board with microprocessor part and power electronics
• Key and indication board (program: EASYCONTROL II with temp. Display or QUICK-CONTROL
with adjusting knob)
• Sensor board with rotor detection sensors
• 3 phase induction motor with integrated thermal over-temperature switch (C. O. 150°C)
• Speed detection and imbalance board with filter attached to the motor’s bottom by screws
• self-closing door locking system (mechanical bolt keeper, motor dis-locking)
• 2 parallel brake resistors mounted on safety chamber (one with overtemp.sensor)
• axial-flow fan for power electronics, motor and chamber
3.2 Main Board Functions
The Main board is mounted at the housing behind the front panel. The components on main
board are arranged in following function blocks (see wiring diagram page 4-2 and 4-3).
• Noise filter in accordance with EN 55011 for motor and triac circuits
• Power pack for low voltage supply of microprocessor part and power electronics
• Triac driving circuits for compressor cut-in relay, for 2 independent fan wiring terminals and for
connection of a heater (special use)
• DC intermediate circuit for supply of frequency converter equipped with automatic loading and
voltage (brake) controlling circuits
• Power part inclusive physically separated driving stages
• Microprocessor part with CPU, E-PROM and NV RAM
• Driving component for self-closing lid lock device
• Interface component for serial RS232 (option)
• Exchangeable NV-Ram and E-PROM containing specific data of the unit
3.2.1 Power Pack
The power pack consists of 2 transformers, 2 rectifiers (single diode) and 2 voltage regulators, which
generates the following low voltage levels:
supplies all processors and its electronic components on main and indication board
•U2 = 24V: unregulated
is used for the driving of lid lock motor and relays K2, K3;
the reference potential is GND, VSS
•U3 = 20V: by 2nd transformer, rectifier diodes and fix voltage regulator 7820
serves for supply of driving of the power electronics via the protection circuit by closed lid
switches
reference potential: 0V CAUTION - MAINS POTENTIAL!
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Legend RT
Multifuge 3S-R/3L-R
Main Board Functions
3.2.2 Intermediate Circuit
The DC intermediate circuit serves as an energy store between the AC power input and the
transmitted motor performance. The intermediate circuit consists of a heat-sink-cooled bridge
rectifier and several reservoir capacitors which are softly charged across a power resistor R76 when
ever the unit is switched on. After the loading time (CPU initialization time) the power resistor is
linked by the relay contacts of K3. When switching the unit off, the DC voltage of the intermediate
circuit is discharged across a path of resistor R1, R2.
3.2.3 Brake Path
Electrical power is fed back into the intermediate circuit during motor deceleration (motor acts as
generator). This braking power is transformed into heat by two parallel connected resistors so that
the intermediate circuit voltage does not rise to an excessive level. The brake resistors are switched
into the intermediate circuit by a fast switching transistor (pulse-width modulation, synchronized by
the double mains frequency). This transistor is voltage dependent controlled by a self-acting stage
(closed loop).
3.2.4 Frequency Converter
The motor is 3-phased, provided with chopped direct voltage blocks (chopped frequency approx.
5kHz, amplitude is height of DC intermediate voltage). These blocks are variable in frequency and
pulse-width modulation, 120° out of phase. These 3 phases are controlled during acceleration,
running at set speed and deceleration (e.g. for small speed: low frequency and small pulse-width
length will be affected). The FC is protected against over current, over temperature and over-voltage.
3.2.5 Microcontroller (Central Processing Unit) Part
The software identification No's of the CPU and data storage’s (NV-RAM) ST24C32 are sequentially
displayed in speed and time fields:
Press program place no 2 during switch on
• CPU Operating panel:526P05
• Firmware:528200
• NV-RAM:4468105
The actually indicated version No.'s are displayed in the time field and will be upgraded if program or
data changes are necessary.
The control program (ROM) is integrated in the controller component. The most important operating
parameters (e.g. the maximum data for all rotors, the last operator settings, the basic values for
speed and temperature controlling, data of acceleration and deceleration curves as well as 4 data
sets of program places are stored in the non volatile (NV)-RAM.
When calling this routine the actual value of all centrifugation cycles (“CYL“) is also shown in the
display (as fourth No.) before the check routine for all program places puts an end to the initialization
time (approx. 18s).
The CPU co-operates with the E-PROM component via the 16 bit data bus and some control lines.
The CPU is an integrated circuit, generating all required output signals, monitoring and analyzing all
input signals.
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Legend RT
Multifuge 3S-R/3L-R
3.3 Key and Indication Board - Easycontrol
The key and indication board is mounted behind the operating panel. The connection to the main
board is done by a 4 pole cable by which the serial data transfer as well as the low voltage supply of
5V is verified. The 7-segment displays, the control LED’s and the operating keys are managed by an
own controller unit (first identification No. 591) in multiplex processing.
For the programming serves EASYCONTROL II (see Operating Instructions).
Functions of keys elements (Easycontrol)
KeysDesignationFunction(s)
S1 – S4
S5Arrow upAcceleration profile 1 to 9
S6Arrow downDeceleration profile 1 to 9
S7Speed arrow downDecrement the value of the set speed
S8Speed arrow upIncrement the value of the set speed
S9BucketSetting of the rotor / bucket number
S10At the same timeSwitching between rpm and rcf display
S11Time arrow downDecrement the value of the set time
S12Time arrow downIncrement the value of the set time
S13Temp. Arrow downDecrement the value of the set temperature
S14Temp. Arrow upIncrement the value of the set temperature
S15FrostPre cooling
S16Double arrowQuick run – hold button pushed
S17Lid symbolOpen the lid
S18Arrow rightNormal start of the centrifugation
S19Red square
Program
place 1 to 4
Store or recall programs
Manual stop of a run
Functions of Indicating Elements (Easycontrol)
Indicat.DesignationFunction(s)
H1BuzzerAudio signal
H2Accel. curve digitDisplay defined acceleration curves 1 to 9
H3Decel. curve digitDisplay defined deceleration curves 1 to 9
rcf-value (xg) or not yet possible to calculate „-----“
Identifications no.’s of controller and NV-RAMs,
Lid open condition („OPEn")
Centrifuge run is terminated („End")
Error messages („Lid“, „E-xx“, „bAL“, „rotor“)
Centrifugal time in h.min (count down process)
Count up process (hld) in h.min (count up process)
Actual version number („xx“)
Sample temperature in °C± 2K when pre-cooling or
pre-heating process is terminated
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Legend RT
Multifuge 3S-R/3L-R
Key and Indication Board - Quickcontrol
The key and indication board is mounted behind the operating panel. The connection to the main
board is done by a 4 pole cable by which the serial data transfer as well as the low voltage supply of
5V is verified. The 7-segment displays, the control LED’s and the operating keys are managed by an
own controller unit (first identification No. 591) in multiplex processing.
For the programming serves Knob control system Quickcontrol (see Operating Instructions)
Functions of keys elements (Quickcontrol)
KeysDesignationFunction(s)
S1Adjusting knobSet point temperature
S2Adjusting knobSet point time
S3Adjusting knobSet point speed
S6Arrow upDeceleration profile 1 to 3
S9BucketSetting of the rotor / bucket number
S10At the same timeSwitching between rpm and rcf display
S16Double arrowQuick run – hold button pushed
S17Lid symbolOpen the lid
S18Arrow rightNormal start of the centrifugation
S19Red square
Functions of Indicating Elements (Quickcontrol)
Manual stop of a run
Indicat.DesignationFunction(s)
H1BuzzerAudio signal
H3Decel. curve digitDisplay defined deceleration curves 1 to 3
rcf-value (xg) or not yet possible to calculate „-----“
Identifications no.’s of controller and NV-RAMs,
Lid open condition („OPEn")
Centrifuge run is terminated („End")
Error messages („Lid“, „E-xx“, „bAL“, „rotor“)
Centrifugal time in h.min (count down process)
Count up process (hld) in h.min (count up process)
Actual version number („xx“)
Sample temperature in °C± 2K when pre-cooling or
pre-heating process is terminated
Edition: 03Servicing Schedule
13.03.01/hePage: 3 - 4
Legend RT
Multifuge 3S-R/3L-R
3.4 Speed Detection Board
On a small board, which is attached underneath the motor, the circuits for speed detection and signal
shaping are arranged. The motor speed is optically detected by an infra-red light barrier. The motor
axle has a hole at the same level as the light barrier. This effects that the light beam will be
interrupted twice during one motor revolution. A following pulse shaping stage on board forms
square-topped pulses which are led via XW1 to the main board. The speed pulses are counted by
the CPU to display the exact motor speed.
3.5 Rotor Indication
In the rotor’s bottom 4 magnets are forced, being alternately arranged in polarity and positioned to
each other to different distances on a constant circular ring (segment steps of 20°).
A Hall sensor is exactly fixed below to the sensor board. The magnets are switching a flip-flop stage
by which different pulse lengths and pulse intermissions are generated during one rotor rotation. By
this signal the CPU is able to detect up to 65 different rotors and the correct direction of rotation, too.
3.6 Imbalance Detection
On the speed detection board a piezoelectric acceleration detector is additional fixed. Dependent of
the rotor imbalance this sensor generates an analogous voltage signal which is led via a following
band-pass filter to plug connection XW1/2 to main board, where it is analysed by CPU. When the
CPU) has identified the installed rotor type, the speed dependent imbalance limitation curve from EPROM The analogue imbalance signal is filtered, converted into digital form and continuously
comperated with this specific limitation curve. If the actual imbalance signal will rise at any speed
beyond the limit, the error signal for imbalance load “bAL“ will be displayed and the unit slows down.
3.7 Lid lock system
The latch is directly controlled by CPU via a PWM motor driver. If all necessary signals are existing
which allow an opening the motor is fired with a pulsed voltage of 24 VDC. For additional safety the
relay K2 will be activated if the speed is below 120 rpm controlled by triggered mono-flops.
3.8 Cooling plant
The Multifuge 3SR/LR, Legend RT is equipped with a high-grade cooling plant, to meet it’s
requirements of driving power and compact design. The CFC free refrigerant R404A evaporates at
low temperatures (≤ -20°C) and absorbers through this the frictional heat from chamber produced by
the fast spinning rotor. 5 fans serve for even air flow through condenser so that the refrigerant’s
condensing temperature is kept on a low level (lateral front fans are only switched on, if n > 0 rpm).
A specially designed coaxial heat exchanger serves for essential undercooling of the condensed
refrigerant to ensure an optimum evaporation and a perfect operation of the expansion valve. To
maintain low evaporation and resultant condensation temperatures on one hand and to support the
starting procedure of the compressor on other hand, a thermostatic expansion valve with 3.0bara
MOP is used.
The minimum achievable sample temperatures are depending on speed, rotor type and a little on
ambient temperature. After a compensating time, given by the pre-cooling or pre-heating program as
optimal result, the rotor has reached the selected set temperature within a tolerance of ± 2K.
To reduce the power consumption of the unit the compressor will not be activated during
accelerating of the motor. When reaching the selected speed the compressor will be activated if a
low temperature had been selected.