XP7000/XP5000
49
3.
Example of Repair
All DC voltage is not output from secondary side.
3-1
Instruction
Follow the instruction below. (See section 3-2 and diagram 3-3 on page 64.)
1
Check the resistor value of R410 and R411 (6.8 ohms, 5 W).
If opened, replace R410 and R411.
2
Check the resistor value between C-E of Q406 and Q407.
If short-circuited or the resistor value lowers by several values (ohm), remove Q406 or Q407. Also replace IC402 because
it is broken.
3
Check the resistor value of R421 and R422 is 10 ohms.
If opened or the resistor value increases, replace R421 and R422.
If short-circuited or the resistor value is extremely small, replace D409 and D410. After replacing D409 and D410, check
the resistor value again.
4
Check the resistor value of R420 is 4.7 ohms.
If opened or the resistor value increases, replace R420.
5
Check the resistor value of R431 and R432.
If opened or the resistor value increases, replace R431 and R432.
6
Check the resistor value of F401.
If opened, replace F401.
7
After checking items
1
to
6
, put the AC power and check the waveform between pin 1 (LO) and pin 2 (COM) of IC402 with
oscilloscope. Check the measured waveform is the recutaugular wave (0-15 V) around 70 kHz.
If the measured waveform is abnormal, check the output of IC403 (3-pin regulator) is +15 V.
If the output is less than +15 V, replace IC402 and check the waveform again. If IC402 is already replaced, replace IC401.
* When measuring the waveform, short-circuit PR401.
8
Check the “2. Electrical Performance” is satisfied. If satisfied, repair is finished.
