Troubleshooting Power Supply Unit 20Ps203 - Philips DVD 950 Service Manual

Electrical diagrams and Print-layouts

TROUBLESHOOTING POWER SUPPLY UNIT 20PS203

Check DC voltages
+12V, +5Vstby, -5V, +5V, +3V3, +2V9
NOK
Disconnect the power supply from the MAIN Board
Connect dummy load resistors 10W(min 5W):
10 ohm at +3V3, 15 ohm at +12V and ground
Check DC voltages
+12V, +5Vstby, -5V, +5V, +3V3, +2V9
These voltages will be somewhat higher than specified
NOK
Check the +3V3 and12V
NOK
connect the mains inlet to a mains
isolated variac
turn input voltage up and check across C2121
the voltage
this voltage should be 1,41 x Vin AC
±
OK
is power supply ticking?
NO
check Vcc on pin 1 IC7110
Vcc = 12V...... 16V
OK
Power supply is OK
DVD 950
OK
power supply OK
OK
power supply is OK
⇒
check:
⇒
digital board
A/V MUX board
display board
check the path of the fault voltage: 7233, 7259, 7236,
⇒
OK
7237, 7221
Standby circuit
⇒
+12V: check 6240, 2240, 5240
⇒
+3V3: check 6210, 2210, 5210
OK ⇒
check the functionality of the following components:
NOK
⇒
1120, 3122, 5120, 6120, 2121
check the load on the secundary output
⇒
check overvoltage protection: 3135,6114,2114,3115,3116
⇒
YES
check oscillator voltage on pin 10 of IC7110:
⇒
check 2102,3110, replace 7110
check drive circuit: gate voltage of MOSFET 7125,
⇒
components 3112,3113,2113,3125
check working of regulation circuit
⇒
measure voltage on pin 6 of IC7110 with oscilloscope
•
if > 2.5V check the regulation circuit: 7200, 7201,
•
6275,6278,3201,3202,3204,3205,3206,2201,2202
3104,3105,3106,3109,2104,2106,2109
NOK
Check start circuit and Vcc supply:
⇒
3123,3134,2129,6129,3129,3111,2111,3133
replace 7110
⇒
6. 32
Personal notes:
CL 96532065_072.eps
130799