Peak-Peak; Tv Triggering; Dtb Trigger Pre-Amplifier - Philips PM3055 Service Manual

5-3
Integrated circuit D2304 serves as
an auto level circuit.
The following functions are
possible,
a.
Peak-peak
I„ thi. c.s. the
-plitude
of the
trigger signal .pplied
to
D^O
(
3
.
7
)
is
™.-redJ.y
peah-^ah
detector, on^
^e»:r.nr;d
3
r.hL
ti^J ;Je LEVEL
Latml R7012. connected to
D2304(1).
b.
Triggering
Tn
this case the level
range
is 16
div. The level is
adjustable
with R7012 and the
current variation on D2304 (14,15) can be
varied
between
+or- 0,6tnA.
c.
TV triggering
The level control
is
made ineffective.
In TV triggering, the
LEVEL
must
be set
to a
fixed value. This is
done by applying a
high level
currant to
pin
1
via diode V2326,
d
.
Auto
In
auto the signal LEVEL ZERO is
high and
via diode
V23^
the
output
level D2304
(15) is
asymmetrical with output level D2304
(1 ).
Thus the Tnaxitnum
signal amplitude
is
2
Vp-p.
-
an ontnrnal
deflection
path, rooted via the
series feedback
V2356
and
V2357,
the
X DEFL+ and
X DEFL- signals
are
fed to the
time
base unit A2,
,
,
v v
air
R2416, R2422 and C2350 gives phase
correction
for the
X Y display.
5.3
DTB
TRIGGER
PRE -AMPLIFIER
Trigger possibilities
are:
Signal
name
routed to
Selected by:
Inverted by:
name
routed to
name
routed to
u
A
TRAn+ TRAD-
D250K3
4)
AD
D250l(10)
INVAD D2501(2)
A
D2501(5.^
BD
D250K11)
INVBD D2501(7)
external EXT+,'
EXT-
D2502(5,6)
EXTD
D2502(ll)
INVAD D2502(7)
Similar to
the
main
time base triggering, signal
splitter D2301 applies
the
EXT current to
the 0Q0020.
The LEVEL control R7014 is
connected
to
D2502-1
to
obtain
a level rang,
of 16
div.
The output of
both integrated circuits, pin
13
and
14.
are routed via
a
shunt feedback V2512, V2513, followed by a
V2514, V2516
and
provide
the
DTB trigger signals TRIGD- and
TRIGD
.
These 'signals are
fed to the
time-base unit A4.