Service manual

- alsa apparecchi medicali s.r.l. -

Pag. 7

(TP “F”)

THERMAL PROTECTION CONTROL

Turn the device on shorting the NTC R79 pins on the Power supply board. The display should show the

alarm code “Err Ht2” with acoustic alarm signal.

Turn the device off and on again to restore normal running conditions.

CONTROL OF THE REFERENCE VOLTAGES FOR THE A/D CONVERTERS

Many of the controls and settings automatically carried out by the unit depend on the calibration of these

voltages. Therefore these values must be particularly precise.

1)On the Microcontroller board, connect the multimeter to TP “G” (R64), calibrate the R70 pot to obtain a

voltage of 4.81V (±0.01 V); connect the multimeter to TP “H” (R66) and calibrate the R68 pot to obtain a

voltage of 110mV (± 0.002 V).

2)On the Panel board, connect the multimeter to TP “I” (LM431) and calibrate the R24 pot to obtain a voltage

of 4.81V (±0.01 V).

CONTROL OF THE LOCAL OSCILLATOR AND OF THE DRIVING SIGNALS

To start the following tests perform the selection detailed on the table below

Setting Memory Monopolar Cut Display Monopolar Coag. Display

M II

1)Select M I

2)Connect the oscilloscope to TP “J” (R.F. driver board)

3)Turn the unit on but not activate it and check the signal: it should correspond to the following wave form (f=

940 kHz ± 5kHz): Turn the unit on but not activate it and

(TP “J”)

The DRVRF2 signal drives the MOS-FETS on the R.F. power board.

2)Disconnect J5 connector of the Power Supply Board, in order to avoid any damages (if the control

circuits for the driving signals of the power section should be faulty).

3)Connect the oscilloscope to TP “K” (D8) of the R.F. driver board, set function monopolar PC, activate the

device and check DRVRF2 signal. It should be as below specified, with a pulse width of 440 ns (±20 ns) (if

necessary calibrate the R13 pot on the same board):