RADIOMETER TCM3 - Page 75

TCM3
and
TCM30
Service
Manual
2.
TCM3
Power Supply PCB
Introduction
Two Versions
Switching
Transformers
199808-1
The
PCB
contains
a
switching
regulator
power
supply
system
and
a
communication
system
for
the
analog
output
and
the
serial
data
input-output.
The
power
supply
part
has
the
following
power
inputs:
12
V
AC
or
DC,
supplied
from
J1
terminal
1/3
,
9
to
21
VDC
supplied
from
J5
terminal
6/1,
or
7
to
21
VDC
supplied from J5 terminal
2/1.
Normally,
J1
terminal
1/3
is
used
for
the
mains
adapter,
J5
terminal
1/2
for
the
battery
cassette,
and
J5
terminal
6/1
for
the
recorder
TCR3
and
REC
(TCM3
only).
The
communication
part
has
two
selectable
alternatives.
Either
analog
outputs
or
serial
data
input/output.
A
strap
between
two
connector
pins
selects
the
analog
alternative.
Two
opto-couplers
interface
the
communication
channels
to
the
Main
PCB.
They
are
mounted
on
the
Analog
PCB
and
are
part
of
the
patient
barrier.
The
communication
part
is
active
only,
when
power
is
supplied
via
J1
terminal
1/3
or
J5
terminal
6/1.
Please
note
that
two
versions
of
the
Power
Supply
PCB
exist.
The
table
below
gives
an
overview
of
the
versions
and
their
compatibility.
Part
Used
for
Compatibility
|
Drawing
901-644
|
TCM3
below
R22
None
2371-Al
901-832
|
TCM3
of
R22
onwards
and
TCM30
|
None
2438-A1
The
transformer
primary
winding
receives
the
switching
power
from
O1
and
delivers
it
to
the
secondary
where
it
is
rectified
and
filtered.
The 3rd winding (terminals 3-4) has 3 purposes:
It
increases
the
efficiency
of
the
system
by
transferring
energy
back
to
the
charging
capacitors
(C11,
C1,
C10,
C69)
via
CR10
and
CR11.
This
occurs
when
Q1
switches
off
the
primary
current.
e
It
delivers
the
input
power
for
the
integrated
DC
regulator
QA53
and
the
serial
data
output.
*
It
compensates
for
the
secondary
rectifier
diode
voltage
drop
via
CR9
and
the
integral
regulator
QA2.
The transformer pulse signals are shown overleaf.
Continued on next page
2-59