WARNING
1)
SUPPLY
The input supply of the monitor (128 V a.c.) must be fed via a mains isolating transformer.
2)
EARTHING
The chassis and the heat sinks are connected to earth. To measure voltages and to inspect waveforms,
connect the negative
terminals of instruments to the chassis.
3) X-RAYS
The monitor has been designed to minimize x-ray radiation. Furthermore, a special safety circuit comes
into operation
in
the event of failure to limit radiation to below 0.5 mR/h.
4) E.H.T.
Dangerously high voltages are present inside the monitor, and for safe operation it
is
imperative to
follow all safety instructions and warnings.
5) C.R.T.
The cathode-ray tube
is
a high vacuum device and its surfaces are subject to high external pressure.
It
is
therefore necessary to handle the tube with care and to avoid impact which could cause implosion.
It follows
that personnel handling cathode-ray tubes during installation or during replacement, should
wear thick gloves and protective clothing to protect against possible flying glass splinters.
6)
WEATHER PROTECTION
To avoid the possibility of electric discharge, do not expose the monitor to rain or excessive humidity.
PROTECTION AGAINST X-RAY RADIATION
+
12V
1-------11~--..,.._
C35
22µF
PIN
8 0
1
0
TOA2595
(D.H.H.S. accession
n.
8720899-05)
017
PIN
10
~~~----~~[]
TH2
1%
,J_,
C45
I
1u
The MTC
911
O monitor contains
an
x-ray protection circuit. A reference voltage
is
generated from the
E.H.T. transformer and
is
fed via a resistive divider to pin 8 of l.C. TDA 2595.
The
voltage appearing at pin 8
is
compared with an accurate reference voltage within the l.C., and if
the E.H.T. exceeds
30 kV the voltage at pin 8 operates a trigger circuit which inhibits the oscillator and
hence the generation of the E.H.T.
The circuit continues to
block the oscillator until the cause of the failure has been repaired, and can
only be reset by completely switching-off the monitor and switching-on again.
8
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