Pioneer PDP-502MX Service Manual page 56

PDP-502MX, PDP-502MXE
Procedure Adjusting Item
6 VOFS/VH/IC5V
Voltage adjustment
Note) Be sure to measure between specified test points.
Sustain Pulse
7
Waveform
adjustment
56
Input signal Adjusting Point
VR700 (VOFS)
Y DRIVE ASSY
VR750 (VH)
Y DRIVE ASSY
White 100%
signal
VR851 (IC5V)
Y DRIVE ASSY
DRIVE ADJ mode
in Factory mode
X-SUS-G......."2" Key
Y-SUS-G ......"4" Key
DRIVE ADJ mode
in Factory mode
X-SUS-B......."1" Key
Y-SUS-B ......"3" Key
White 100%
signal
Adjusting Method
VOFS (Offset voltage) adjustment
Adjust so that the voltage between TP705 (VOFS) and TP703 (SUS
GND) becomes ± 0.5V" of the voltage indicated at the "voltage
indication label".
The symptom in case of mis-adjustment
If the VOFS adjustment is not performed properly, dots like blinking
luminance points appear. If deviated greatly from the right adjustment
point, Panel will light white.
VH (voltage for Scan IC) adjustment
Adjust so that the voltage between TP751 (VH) and TP753 (PSUS)
becomes "103V ± 0.5V".
PSUS (=GNDH) is a floating GND and the electric potential is different
from that of chassis GND. Be sure not to short-circuit PSUS (=GNDH)
and another GND, because that may damage the unit.
The symptom in case of mis-adjustment
If the VH adjustment is not performed properly, dots like blinking
luminance points appear. If deviated greatly from the right adjustment
point, panel will light white.
IC5V adjustment
Adjust so that the voltage between TP851 (IC5V) and TP854 (PSUS)
becomes "+5.0V ± 0.1V".
PSUS (=GNDH) is a floating GND and the electric potential is different
from that of chassis GND. Be sure not to short-circuit PSUS (=GNDH)
and another GND, because that may damage the unit.
X-SUS-G, Y-SUS-G adjustment
Set to the indicated value with a key on the remote control unit.
(refer to DRIVE ADJ mode)
X-SUS-B, Y-SUS-B adjustment
1) Set adjustment value to "8", and confirm that green mis-discharging
dots do not appear within 20mm from top & bottom of Screen.
2) When green mis-discharging dots appear, decrease the adjustment
value "1" by "1" until green mis-discharging dots will disappear.
Set the adjustment value when the green disappear.
3) Observe sustain waveform at each Drive Assy, between K3402
(X-PSUS) and K3404 (SUS-GND), and TP3716 (Y-PSUS) and
TP3713 (SUS-GND). Confirm that the waveform is not distorted.
The symptom in case of mis-adjustment
Green mis-discharging dots
appear within 20mm from
top & bottom of Screen.