Service manual

- alsa apparecchi medicali s.r.l. -
Pag. 2
This handbook has been written to provide skilled personnel with a method required to set and
check the characteristics of the device and to assist the user, if necessary, in the identification of the
most frequently encountered faults.
INSTRUMENTS REQUIRED
DESCRIPTION TECHNICAL CHARACTERISTICS EXAMPLE
Oscilloscope Dual channel - Band width: > 40 MHz Tektronix mod. TDS210
Digital Multimeter TRMS reading - Precision: 3% Metrix mod. MX54
Current probe Band width: 200 Hz÷50 MHz Tektronix mod. P6021
Tester for H.F. leakage
and output power control
with antinductive loads
from 50 to 1500 ohms
Precision: 5%
Automatic tester as
Dynatech DNY 454A
Or
Single loads and
thermocouple instruments
RMS with scale
0-250 or 500 mA and 0-1,5
A
Set of materials needed
for control and calibration
Extended wirings,
EPROM memory “calibration and control”
Etc.
Automatic tester for low
frequency leakage control
(1)
Responding to IEC 601-1 International standards
(able to perform tests according to)
Different models of
Company METRON,
Company DYNATECH;
Etc.
INTRODUCTION
The electrosurgical unit EXCELL MCDS is a HF generator, completely controlled by two microcontrollers,
with, as power section, a dumped oscillator (working at a frequency of 475 kHz), able to deliver by output
transformers (for monopolar or bipolar section) a maximum power or of 400 Watt for the monopolar
performances and of 99 Watt for the bipolar performances.
The unit, provided of every possible device needed to select, control and activate different performances and
functions, consists of 4 main sections:
- Power supply section;
- H.F. power section;
- Microcontroller section;
- Output Power reading section.
The power supply section supplies all the continuous voltages required in the device.
These voltages are:
♦ +5V (continuous) for the programmable system;
♦ +15 –15 V (continuous) for driving circuits;
♦ from 0 to 150 V (adjustable) for power supply of H.F. section.
The first three voltages (+5 V and +15 – 15 V) are obtained by means of three linear voltage stabilisers.
The adjustable voltage is obtained using a switching section (configuration FORWARD type), powered by the
mains transformer. The "heart" of this power section consists of a PWM 3525 circuit (working at a frequency
of 115 kHz) driving, by means of a SIRIO transformer (three windings with 1:1:1 transformation ratio),
alternately two MOS-FETs (best choice IRF 740).
The enabling signals and the settings of the power supply of H.F. section, type PWM, are provided directly
by the Microcontroller board.
The microcontroller section controls the correct running of the whole device performing a continuous
autodiagnosis in order to detect any anomalies or damages in the unit or in the accessories connected to it.
For this purpose a main self-test phase runs both every time the unit is turned on and cyclically about every
45 minutes of working. If the system detects a fault the device is stopped until the cause is eliminated
and the display on the front panel shows a error code (see the following table) that provides the operator with
a specific information about the type of fault detected. So some useful information is indirectly achieved
(1) The test of LF leakage current can be performed also by a circuit corresponding to that indicated in the Par. 19.4 of IEC
601-1; using this circuit it is necessary even a rotary transformer (1,5 kV) to adjust the mains supply