Hitachi P50H401/DW3-U Service Manual page 59

We have a procedure to isolate panel PWB's, which is a separate sequence of tests.
If Power Supply is protecting itself, easy to tell when we measure Va and Vs and it will
come up and then will go down. These voltages go together with the Vsego and Vsago
from the Logic PWB assy. These voltages will too come up and go down as well, these
are the voltages turning the Vs and Va on.
1
SDRU
Y SUS
2
SDRD
On this lay out, have technicians start eliminating the SDR PWBs first.
Remove the lower SDRd from Y SUS and try turning TV on.If this SDR is
causing the problem (protection),TV will come on and will give you a good
picture on the upper half and VA,VS will stay up. Do the same procedure
for the upper SDRu,if the upper SDR is the problem then you will have a
picture on the lower half and VA,VS will stay up.If neither of the SDR's
correct the protection problem, remove connector 3 to lower ABUS pwb's and
check VS,VA voltage, if still protected remove connector 4 to upper ABUS
pwb's and check VS,VA voltage.(Some models do not have upper ABUS pwb's)
Remember to remove and reinsert connectors CN63 & CN64 on PS pwb after
each test,This will reset the protection circuit.
ABUSU
ABUSD
6
Back to PG.1
4
X SUS
3