Pioneer PDP-502MX Service Manual page 63

Diagnosis when under voltage is detected at V SUS / V ADR voltage lines.
Disconnect connector CN205 P5 at Main Power Assy and turn on the power.
If the power is turned on and D205 at Main Power Assy lights up in yellow, cause of the under voltage is not inside Main Power Assy.
If P.D. occurs, V SUS / V ADR DC-DC Converter block at Main Power Assy may be defective.
Diagnosis when under voltage is detected at 14V, 12V, +-8V voltage lines
Be sure to turn off High Power CUT SW, S301 at Power Supply Assy. (important)
Disconnect CN306 P6,CN355 P4, CN354 P3, CN353 P2 at Main Power Assy one by one, and turn on the power of the unit.
(Do not disconnect all four connectors at the same time and turn on the power. Because this leads to no load of power supply and that is
very dangerous.)
When the power is turned on with a connector disconnected, and if Low power supply DC-DC Converter operates normally with lighting
D355 and D205 in red, cause of under voltage is not inside Main Power Assy.
If P.D. still occurs after disconnecting each connector, 14V DC-DC Converter block at Main Power Assy may be defective.
The function of High Power CUT SW, S301 at Main Power Assy
When S301 is turned off, V SUS / V ADR DC-DC Converter does not operate. However, 14V DC-DC Converter operates normally.
Therefore, diagnosis from Signal Input circuit to before Drive circuit is possible without danger of breaking Drive section by mistake.
AC100V/AC200V Change-over SW, S111 at Main Power Assy
Only PDP-502MXE is set to AC200V.
When the SW is set to AC100V, AC200V P.D. detecting circuit will operate. (Even when the unit is in Stand-by mode, the detecting circuit
is in operation.)
Diagnoses of the malfunctions by LEDs at Digital Video Assy, D2302/D2306
LED Title (Color of Light)
D2302 STOP (GREEN) Lights on in normal operation
It lights up at every V rate, when Drive pulse output from IC2201 is normal.
D2302 PBusy (RED) Light is put off in normal operation.
It lights up when System Control CPU (IC3604) and Panel CPU are
communicating.
D2306 IP Busy (RED) It lights up at every V rate during IP processing.(Video input)
Light is put off when IP processing is not done. (PC input)
Diagnosis of malfunctions other than the operation of protection circuits
The state of the unit
STBY indicator does not light at all
Power does not go on
Power shuts down immediately after power on.
(back to Stand-by)
Dots like luminance spots appear on the screen.
Screen does not emit lights at all.
Fuse is blown.
The timing of lighting
AC power input is not appropriate.
Stand-by power supply block is defective.
U-com Assy is defective.
Connectors disconnected.
U-com Assy is defective.
Drive section voltage is abnormal. (VSUS, VADR, VOFS, VH, VRN)
X Drive Assy and Y Drive Assy are defective.
Scan Module is defective.
DIGITAL VIDEO Assy is defective.
Q131–Q136, D131, IC131 Defective
R133, R134, R168 Defective
Q201, Q202, RCC Control (A) Assy, OTL Control (A) Assy Defective
Q301, Q302, RCC Control (B) Assy, OTL Control (B) Assy Defective
Q351, Q354, RCC Control (C) Assy, OTL Control (C) Assy Defective
PDP-502MX, PDP-502MXE
Estimated failure parts
Around IC2101/IC2151/IC2801
/X3202 (Xtal)
Around Connector and Panel
CPU and X3202/X3201 (Xtal)
Around IC1801/IC1901/IC2001
Estimated failure mode
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