Hdmi Arc Cannot Work; Optical Cannot Work; Sub Is Interrupted; Sub Can Not Work - Polk Mono Signa S4 Service Manual

5. HDMI ARC cannot work.

Check that [U28 : 1pin is about 3.3V], [U28 : 2pin
is about 5V] and [U28 : 3pin is about 1.8 V] on the
MAIN PCB. Yes or no?
YES
Replace the old HDMI PCB with a new one so that
the EUT functions.
Yes or no？

6. OPTICAL cannot work.

Check the optical connector [U19] is effective on
the MAIN PCB.
Yes or no？
YES
Check that [U1: 5pin] is about 3.3V on the MAIN
PCB.
Yes or no？
NO
Switch the source to BT, is the EUT working in BT
source?
Yes or no？
YES
Replace the MAIN PCB.
NO
Replace the MAIN PCB.
NO
Replace the HDMI PCB.
NO
Replace the optical connector.
YES
Replace the [U2] with a new one.
NO
Replace the [U1] with a new one.

7. SUB is interrupted.

Check that the wireless antenna connector on the
MAIN PCB [CON2] is effective.
Yes or no?
YES
Check that the wireless antenna is effective and
connected with the [CON2].
Yes or no？
YES
Check that [R117] is about 3.3V on the MAIN PCB.
Yes or no？
YES
Replace the MAIN PCB.

8. SUB can not work.

Check the [4pin cable] and confirm that it is
connected to the AMP PCB.
Yes or no?
YES
Check that [XP3: 3, 4pin] is about 23.5V on the
AMP PCB.
Yes or no?
YES
Check that [FB605] is about 3.3V on the AMP PCB.
Yes or no？
YES
Replace the AMP PCB.
45
NO
Replace the wireless antenna connector.
NO
Replace the wireless antenna with a new one.
NO
Replace the [Q11] with a new one.
NO
Reconnect instead.
NO
Replace the SUB SMPS PCB.
NO
Replace the [U1] with a new one.