Panasonic UF-5500 Service Manual page 169

11.2.10.2. DEFECTIVE ITS (Integrated Telephone System) Section
1. No speakerphone transmission / reception
Perform a signal test in the ITS or the NCU section and locate a defective point (where the signal disappears) on each route
between the microphone and the telephone line (sending), or between the telephone line and the speaker (receiving). Check the
components at that point. Check Sheet (P.168) is useful for this investigation.
2. No pulse dialing
Connect a PBX and TEL line and
go to the off-hook. status
3. No ring tone (or No bell)
CROSS REFERENCE:
Check Sheet (P.168)
NCU Section (P.36)
Check the bell detection circuit
(Refer to NCU SECTION).
Is the bell detection circuit OK?
YES
Does a ring tone signal
appear at pin 15 of IC100?
YES
Following the ITS section, search for the point
where the signal disappears on the route between
IC300 and speaker and check the components
at that point.
(RINGING: Refer to CHECK SHEET.)
Check Line current.
Is there any Line current exist?
Replace Q102~Q106
Replace IC100, IC101
NO
Replace C109, C110,
R106, R107, R112, R113
NO
Replace IC100, IC101.
169
NG
NG
UF-5500 / 4500