Pioneer XR-P270C Service Manual page 66

XR-P270C,XR-P170C
@ IC 1003 (ICP of 400mA) is broken.
¢ The +5.6V line is short-circuited. The 40-core FFC is not inserted straight.
¢ The 6.8V Zener diode of the +5.6V line is short-circuited.
D1003 in the Power assy
D1809 in the LED assy
¢ If the ICP is broken after disconnecting the Power assy from AF assy, IC1001 (78MO05) or its surrounding parts may be malfunctioning.
¢ The ICP is also broken by short circuit of IC1002 (4558).
© The ICP is also broken by B-E short circuit of Q1001 (power TR, 2SC5197/5200).
The stereo set does not operate at all if the 1C1003 is broken.
@ The power of -COM does not switch ON. Nothing is displayed on the LCD.
« AC power is not supplied to the AC50/60Hz line of IC1901.
* Zener D1902 in the LCD assy is short-circuited because the headphone parallel jumper is inserted incorrectly (incorrect direction).
© Is +5.6V supplied?
+ Is XRESET set to "H"? Is resetting completed?
i 1C1005 (ICP of 2A) is broken, although the microprocessor is operating.
* Does the ICP break after disconnecting from the AF assy?
Yes — Inside the Power assy
No — Outside the Power assy
* Connect only the AF assy. (Disconnect the headphone parallel jumper. CN1002)
If the IGP still breaks, AF assy may have short-circuited, or a malfunction may have occurred in the front of +12V REG.
* Connect the 40-core FFC. Be sure that the flexible substrate is inserted correctly.
If the ICP still breaks, short circuit may have occurred in the complex (solenoid, motor, electrostatic Zener, LED assy, and +5.6 ¥ line).
* Connect the CD assy.
If the ICP still breaks, short circuit may have occurred in the CD assy or the FFC of CD.
In such a case, the 5V PP REG is short-circuited. Check for short circuit in Q1003-1006 and D1011. (Because of the structure of the
circuitry, short circuit is difficult to be detected by a tester. Replacing the circuitry as a whole will result in faster solution.)
If the headphone parallel jumper is removed, +17V voltage is supplied to u-COM in standby mode. The power amplifier and all power
sources will turn to ON, However, an IC that does not operated without serial data cannot be diagnosed.
@ Although sound is output, discontinuance occurs at full power.
* Vp is adjusted to high level. (The protective function for the power-amplifier ICs tums to ON.)
* Dedicated speakers for the system are not used. The protective circuit turns to ON during clipping if speakers with high inductance are used
even though they have high impedance.
¢1C120] (TDA8560Q) is malfunctioning. + Replace the IC.
* LPF(C1201, C1202 [2200pF]) of IC1201, are not installed.If they are not installed, the system interferes with the preamplifier IC and
causes oscillation, resulting in muted IC1201.
* Check for short circuit of the negative © terminals of L/R if the measuring instrument is connected to the SP terminal. If line noise from
the measuring instrument is added, the power amplifier IC mutes and causes cracking noise.
* The power amplifier or +17V REG oscillates. Check Pin7 of IC1002 (4558) for major oscillation waveform appearing at the same time as
with the cracking noise.
The power amplifier IC tends to cause discontinuance of sound with a slight oscillation or high-frequency noise.
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