Electrical diagrams and Print-layouts
32
DVD 950
6.
TROUBLESHOOTING POWER SUPPLY UNIT 20PS203
power supply OK
Check DC voltages
+12V, +5Vstby, -5V, +5V, +3V3, +2V9
These voltages will be somewhat higher than specified
Check DC voltages
+12V, +5Vstby, -5V, +5V, +3V3, +2V9
OK
YES
NOK
NOK
NOK
OK
NOK
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
⇒
power supply is OK
⇒
check:
digital board
A/V MUX board
display board
OK
NO
OK
OK
OK
Check the +3V3 and12V
⇒
+12V: check 6240, 2240, 5240
⇒
+3V3: check 6210, 2210, 5210
⇒
check the path of the fault voltage: 7233, 7259, 7236,
7237, 7221
⇒
Standby circuit
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
⇒
check the functionality of the following components:
1120, 3122, 5120, 6120, 2121
check Vcc on pin 1 IC7110
Vcc = 12V...... 16V
is power supply ticking?
⇒
check the load on the secundary output
⇒
check overvoltage protection: 3135,6114,2114,3115,3116
⇒
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
⇒
Check start circuit and Vcc supply:
3123,3134,2129,6129,3129,3111,2111,3133
⇒
replace 7110
Power supply is OK
CL 96532065_072.eps
130799
Personal notes: