Sony KD-34XBR2 Training Manual page 91

3. +19Vdc OCP – The 19Vdc line is from the secondary power supply. The load is the audio output stage. If the
19-volt line were loaded down, its voltage would drop. If it drops below 15Vdc, D6122 and Q6101 turn ON to trip
the latch formed by Q6105 and Q6119. This latch shuts down the TV.
4. +22Vdc OCP – The +22Vdc line from the secondary power supply (IC6001 – G board) supplies the conver-
gence amplifiers and the Dynamic Focus circuitry on the D board (not shown). D6126 and Q6101 monitor the
+22V on the G board for low voltage. This circuit would shut off the TV if the 22-volt line dropped to 8.2Vdc.
Testing – If the TV Power ON and Surge (not shown) relays turn ON but quickly turn back off with NO standby light
indication, use figure 20-5 to determine which one of the four circuits is causing the shutdown:
BEGIN
G Bd
Turn on TV with Audio
Out CN6102 unplugged
Does TV stay on 3?
No
G Bd
Does PH6004/pin 3
remain below 1Vdc at
Power ON? (use Cold
GND Normal = 0V)
No
GBd
Does PH6004/pin 2
drop from 13.6Vdc
(norm) to 0Vdc at
Power ON? (Use Hot
GND)
No
GBd
Does the 15V line at
CN6106/pin 3 rise
above 20Vdc at Power
ON?
No
GBd
Does the 22 Vdc line
at CN6106/pin 6 rise
above 18Vdc at Power
On?
No
22V line is loaded down from the D Bd.
Replace
+22V
Sec P.S.
G Bd.
CN8022/
CN8013
Repair Audio
Output Bd.
RA-5A Chassis
G Bd
Latch is not
Yes
being triggered.
Replace Latch
Q6105, Q6119
Does TV shut
down?
No
Repaired
Yes
AC OVP Circuit is defective.
Check /replace D6016, Q6010
R6065, R6067
Is CN6106/pin 8
resistance to ground
Yes
more than 3k Ohms
(Normal is above 3k
Ohms)
Normal
Replace PH6004
Yes Check:
135OVP-GBd
135OCP-DBd
HP DET
ABd
Q3061
FIGURE 20-5 - FLOW CHART C
D Board
Convergence Amp IC8001/2
Dynamic Focus Stage Q8008-11
Problem is not in
this section.
Yes
Secondary P.S.
Defective(G Bd)
Surge relay sense
circuit DEF(G Bd)
This is the normal load
Yes
resistance so the D Board is
OK. There is excessive voltage
from Secondary P.S. on G Bd.
Troubleshoot or replace G Bd.
No
No load on +15V line,
D bd.
Check Vert Out IC5004
88
20. RA-5A Chassis Protection Block
Shutdown with no indication.
The problem:
*120VAC measures excessive
*15V line above 20 Vdc
*22V line below 8.2Vdc
PH6004
*19V line below 15Vdc
CN6104 CN6102 CN6101
2 4
3
1
PRIM
STANDBY
P.S
P.S
D6015
-
+
AC IN
CN6106
SEC SEC
P.S
P.S
HOT
RA-5A
GND
G BD.
T.P.
D6015 -
35TVP12 9/4/01