Pioneer PDP-503PC Service Manual page 65

5
Timing Adjustment of X and Y DRIVE Assys Control Signal
Purpose
• Pulse module loads in DRIVE Assy as one of heat measures of DRIVE Assy. Adjust the drive timing of the pulse module
driving parallel with VR.
• Pulse module has each peculiar delay time. Readjustment is necessary when replaced the pulse module in the X and
Y DRIVE Assys.
Adjustment Method
CR delay circuit is each inserted on signal path of four control signals (SUS-U, SUS-B, SUS-D, SUS-G) driving
the pulse module.
Quantity of delay can adjust pulse module of one side with VR.
Adjust VR while measuring a waveform of the pulse module, and match a timing.
Adjustment VR
X DRIVE
SUS-U VR3203
SUS-D VR3202
SUS-B VR3201
SUS-G VR3200
Adjustment Procedure
Power ON
Black Mask Screen
Display a SUSOUT waveform
Coarse adjustment of
SUS-U, SUS-B, SUS-G
Display a SUS-D waveform
SUS-D adjustment
Adjust the waveform to 20-25ns.
Display a SUS-U waveform
SUS-U adjustment
Adjust the waveform to 20-25ns.
Power OFF
Adjust VR resistance value
of SUS-B and SUS-G to match
VR resistance value of SUS-D
within ± 2Ω.
As for this adjustment, adjustment with set state is difficult.
Therefore replace it every Assy when replacing the pulse module.
5
6
Y DRIVE
VR2204
VR2203
VR2202
VR2201
Measuring points of waveform
are refered to next page.
6
7
Test pin for adjustment and measurment
Pulse Module X DRIVE
Upper
SUSOUT K3105
SUS-U K3200
SUS-D K3108
Power ON and
display a SUS-D waveform
SUS-D readjustment
Adjust the waveform to 20-25ns.
Display a SUS-U waveform
SUS-U readjustment
Adjust the waveform to 20-25ns.
Power OFF
Adjust VR resistance value
of SUS-B and SUS-G to match
VR resistance value of SUS-D
within ± 2Ω.
Power ON and display a SUSOUT
waveform
No
Compare waveform,
and do harmonize
almost?
Yes
Adjustment end
PDP-503PC
7
8
Y DRIVE
Lower Upper Lower
K3106 K2212 K2203
K3204 K2220 K2224
K3205 K2207 K2225
8
A
B
C
D
E
F
65