Alignment Instructions - AMSTRAD PC1512 Service Manual

ALIGNMENT INSTRUCTIONS FOR PC-CM
Equipment
required:
Digital
Multimeter;
Dummy
Load;
0.82ohm/30W,
D.B.O.Scope;
Odometer
(Teal
Time
Meter),
Diagnostic Disc/Tool.
Step
FUNCTION SIGNAL
IN
SIGNAL
OUT
METHOD REMARKS
1.
To Set +5V.
Power
supply.
Test Point
A
Adjust
VR604
to
read 5.10V
±0
02V.
1)
Refer
to Fig.
1.
2)
Prevent short
circuit
when
pulling
the
PCB
forward.
2.
To Set
+
12V.
Power
supply.
Test Point
B.
Adjust
VR603
to
read 12
15V
+0.02V.
1)
Refer
to Fig.
1.
2)
Prevent short
circuit
when
pulling
the
PCB
forward.
3.
To Set
-5V.
Power
supply.
Test Point
C.
Adjust
VR601
to read
5V ±0.05V.
1)
Refer
to Fig.
1.
2)
Prevent short circuit
when
pulling
the
PCB
forward.
4.
To set -1
2V.
Power
supply.
Test
point D.
Adjust
VR602
to
read 12.0V ±0.05V.
1)
Refer
to Fig.
1.
2)
Prevent short circuit
when
pulling
the
PCB
forward.
5.
To set protect
adjustment.
Power
supply. Pin 11 of
14
Pin
DIN
Plug.
Adjust
VR606
to read 4.5A
on
the
ammeter
in
series with
dummy
load.
1)
Refer
to Fig.
1.
2)
Prevent short
circuit
when
pulling
the
PCB
forward.
6.
V.
Size setting.
Load diagnostics
in
PC1512. Monitor screen. Adjust
VR404
so the
border
is
1
2mm ±3mm
all
around.
Set
optimum
Brightness &
Contrast setting.
7.
Sub
Brightness Control.
Load Diagnostics
in
PC1512. Monitor Screen. Set
VR 102-2
to
max. adjustment
VR101
so
the grey
level
wave
form
is
27% when
initial
white
level
is
100%
against black
scope Q302
collector
1)
Refer
to Fig.
2.
8.
Sub
Contrast Control.
Load Diagnostics
in
PC1512. Monitor Screen.
Select
Colour Bar
Chart.
Set Bright
Control
to
VR102-2
max.
and
VR1
02-1
to
min. Adjust
VR1 03
to set
proper
intensity
level.
9.
Sub
H.
Hold Control.
From IC402
Pin
4.
Scope
Pin 4 of
IC402. Set
VR403
to
Mid position.
Adjust
VR402
to read
Frequency 15.625kHz.
m
NOTE
It
is
very
important
to
observ
the isolated
power supply
area.
Any measurements
within the
power
supply
circuit
should
be
carried with reference
to
top
point of
C505
in
order
to
keep
the
chopper
circuit oscillating.
MAJOR COMPONENTS LOCATION GUIDE
VR403
H.HOLD
00 VR402
SUB
H.H0LD
:^s>
oj—
„VR601
(1-5VADJ.
VR603
12V
AD
J.
Q)
VR604
.
—
5VADJ.LJ
IC101
VR602
-12V ADJ.
Q
VR606
12V
Q
VR101
IGRAY
PROTECT
,
—
iVR103
LJsub
CONT.
Qv.size
IC402
r-GRAY
-f:phnr
f^uyuuui
iNTWurrt
J
Fig. 2.
Fig.
1.
26