Troubleshooting Psu 20Ps317; Cd Main Board - Philips CDR775 Service Manual

GB 58 8.
8.2.2

Troubleshooting PSU 20PS317

+5V, +12V, -8V, VFTD (-38V),VDC1-VDC2 (3V8)
Disconnect power supply unit from CDR main board
+5V, +12V, -8V, VFTD, VDC1-VDC2
These voltages might be somewhat higher than specified
Turn input voltage up and check voltage across C2121,
this voltage should be
8.3

CD 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.
CDR775 Faultfinding Guide
Check fuse 1120 and
replace if necessary
OK
Check DC voltages
NOK
Connect dummy load resistors 10W,
15 ohm at +5V, +12V and ground
Check DC voltages
OK
Check the +5V and +12V
NOK
Connect the mains inlet to a mains
isolated variac
1,41 x Vin AC
±
OK
Is power supply ticking?
NO
Check Vcc on pin 1 IC7110
Vcc = 12V...... 16V
OK
Power supply OK
OK
Power supply unit OK
Power supply is OK
OK ⇒
Check : - CDR main board
⇒
- Display assy
- CD main board for CDR 775
Check the path of the other faulty voltage(s)
⇒
+5V : check 6210/6211, 2210, 5210, 2213
⇒
OK
+12V : check 6230/6232, 2230, 5230, 3230, 6231, 2233
⇒
NOK
Check the functionality of the following components :
⇒
1120, 3120, 2120, 3122, 1125, 3124, 5120, 6102, 2121
Check :
YES Load on secondary output
⇒
Overvoltage protection : 5132, 6114, 2114, 3115, 3116
⇒
Oscillator voltage on pin 10 of IC7110 :
⇒
check 2102, 3110, replace 7110
Drive circuit : gate voltage of MOSFET 7125,
⇒
components 3112, 3113, 2113, 3125
Regulation circuit
⇒
- Measure voltage on pin 6 of IC7110 with oscilloscope
- If > 2.5V check the regulation circuit: 7200, 7201,
3201, 3202, 3204, 3205, 3206, 2201, 2202
3104, 3105, 3106, 3109, 2104, 2106, 2109
NOK
Check start circuit and Vcc supply:
⇒
3123, 3134, 2129, 6129, 3129, 3111, 2111
Replace 7110
⇒
Figure 8-18
The microprocessor controls the CD10 and is slave of the
master processor on the CDR main board in the CDR775. Both
processors communicate via a DSA connection (data, strobe
and acknowledge).
CL 96532076_037.eps
290799