8.2.2Troubleshooting P816
Check fuse F820 and replace if necessary
OK |
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Check DC voltages | OK |
+5V, +12V,
NOK
Disconnect power supply unit from CDR main board
Connect dummy load resistors 10W, 15 ohm at +5V, +12V and ground
| Check DC voltages |
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+5V, +12V, |
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These voltages might be somewhat higher than specified |
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| Check the +5V and +12V |
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Connect the mains inlet to a mains
isolated variac
Power supply unit OK
Power supply is OK
Check : - CDR main board
-Display assy
-CD main board for DR6050
Check the path of the other faulty voltage(s)
+5V : check D856, C857, L856, C859
+12V : check D866, C867, L867, R866, D868, C869
Turn input voltage up and check voltage across C821, this voltage should be ±1.41 x Vin AC
OK
Is power supply ticking?
NO
NOK
YES
Check the functionality of the following components :
F820, R819, C820, L820, D802, C821
Check :
Load on secondary output
Overvoltage protection : L832, D814, C814, R814, R815, R816 Oscillator voltage on pin 10 of Q810 :
check C802, R810 replace Q810
Drive circuit : gate voltage of MOSFET Q825 components R812, R813, C813, R825 Regulation circuit
- Measure voltage on pin 6 of Q810 with oscilloscope
-If > 2.5V check the regulation circuit : Q810, D881
R881- R885, C881, C882, R804 - R806, R809, C804, C809
Check Vcc on pin 1 Q810 Vcc = 12V...... 16V
OK
Power supply OK
NOK | Check start circuit and Vcc supply: | |
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| R823, R834, C829, D829, R829, R811, C811 |
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| Replace Q810 |
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| CL 96532076_037.eps |
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| 290799 |
Figure
8.3CD Main Board
The CD main board is built around the compact disc mechanism VAM1250 and a loader 1250. The CDM delivers diode signals and an unequalised high frequency signal. These signals are necessary inputs for the decoder CD10. Based on these signals the decoder will control the disc. The decoder is able to control the sledge, focus motor, radial motor and turn table. When everything is "locked", the decoder delivers a digital output according to IEC958 standard, subcode to the microprocessor and I2S for reproducing analog audio signals by means of a D/A converter.
The microprocessor controls the CD10 and is slave of the master processor on the CDR main board in the DR6050. Both processors communicate via a DSA connection (data, strobe and acknowledge).
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