Seca 383, 384, 385 Service Manual

Service Manual

Variants:

3831317009
3847017099
3847017229
3847017289
3857017099
8337017249
8347017099
8347017159
8347017249
8347017284
8357017099
8357017289

for seca 383 / 384 / 385 / 833 / 834 / 835

Description:
Digital babyscale based on multi-Load-Cell technology, DMS-Low-End-module,

LCD, battery operated

Content:

Function diagram 25-01-02-560
Description LC-DMS module 30-34-00-729 a
Description of faults 30-34-00-744

Service Manual Number

17-05-01-331-c

Valid as of: 06.07.2011

Calibration 30-34-00-764 a
Cableplan 08-02-06-046
Spare parts 30-34-00-730 b

Manual number: 17-05-01-331-c

Brief description hardware LC DMS-module

Introduction

This compact module is designed to determine and display weights.
Values are shown on a 5 digit LCD with additional fraction marks and icons.
Determination of weights is based on 4 strain gauge load cell technology.
Measurement of the 4 analog load cell values is done by a single discrete dual slope
a/d converter in time multiplex (4 to 1). The a/d converter, the multiplexer and the
display are driven by an integrated Microcontroller. The user interface contains 1
start/ stop button as well as 3 control buttons. All calibrations- and configurations
data are stored in the Microcontroller EEPROM.

load cell 1

load cell 2

load cell 3

load cell 4

clock

multiplexer

a/d converter

µC

| EEPROM |

| power on reset |

voltage regulator

battery

keys

battery monitoring

Figure 1: block circuit of the DMS compact module

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Brief description hardware LC DMS-module

Measurement:

measuring devices: 4 full bridge strain gauges
supply voltage : 5V DC, regulated
a/d conversion: dual slope
conversion time: 8,32ms / load cell
resolution: 0,4198µV

Every 500 ms 12 measurements per load cell are proceeded and averaged out. Each
average value is weighted with the individual correction factor of the load cell. The
conversion from cumulative load cell value to weight is done by using a linear
function.
The first stable value after power on is taken as zero point. Zero point handling
during the use of the scale is done observing certain limits. If those limits are
exceeded an error will be displayed on the LCD.

Display:

Display type: LCD (HTN), reflexive, duty cycle 1/4
Segments: 44
Digits: 5
Digit symbol height: 20mm
icons: 10

Weight-Values are displayed on an LCD. The value range of the least significant digit
is limited to 0 and 5.

Figure 2: visible segments of the LCD

Icons:

Battery pre-warning: Further operation of the scales is possible.
Batteries should be exchanged as soon as
possible. Continued use and discharge of the
batteries will lead to the battery empty­ message “bAtt”. From this point no measure­ ments will be possible.

range 1: Measurement range 1 activated.

range 2: Measurement range 2 activated.

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