Gymna Pulson 330, Руководство по обслуживанию

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14. The display circuit.
The pulson 330 uses 7 segment L.E.D. displays. All display circuits
are placed on a separate PCB, which is installed directly under the
front panel.
14.1 Display circuits.
The display PCB is connected to the main board PCB via CON7.
All display data is coming via SDA and SCK which form the I²C bus.
This I²C bus is connected to multiplexers U1 and U2.
Since each multiplexer has only 16 outputs, which is insufficient to
control all segments and leds, we use the two multiplexed outputs of
U1 ( MX1, MX2). Consequently, transistors Q4 and Q3 alternately
switch, which makes it possible to control all segments and leds.
14.2 Display warnings.
14.2 Display warnings
USH: Connection between instrument and crystal is somewhere
insufficient, or the crystal is damaged. ( see error codes p
23 ).
Flashing intensity value: The contact with the patient is
insufficient. The output power is reduced and the contact
control led on the head lights up.
‘
h
‘ : During initialising the display shows a point on the power
display.
The initialising normally should take about 2 sec.
The same point appears during standby.
CNT: When both timer keys are simultaneously pressed, the timer
is switched off and
the unit works continuously.
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