Panasonic KX-TG2248S Service Manual ▷ View online
19.6. Reception Signal
The voice signal from the base unit is output to DSP (33) (HSSOUT). This signal is led to the headset jack (CN203) and DSP (44)
(HSMIP). The signal input to DSP (44) is inverted and output to DSP (34) (LOUTO).The signal through the headset jack is inverted,
then output from DSP (34) to drive the speaker. When the headset is inserted to the jack, the voice signal is cut at the jack, so the
sound does not come out from the speaker, but from the headset only.
(HSMIP). The signal input to DSP (44) is inverted and output to DSP (34) (LOUTO).The signal through the headset jack is inverted,
then output from DSP (34) to drive the speaker. When the headset is inserted to the jack, the voice signal is cut at the jack, so the
sound does not come out from the speaker, but from the headset only.
19.7. Small P.C.B.
19.7.1. Symptom
Doesn´t work when install the battery in the handset in low temperature condition.
This problem was found during low temperature test (-10deg C).
This is not lock up problem, symptom is doesn´t work when install the battery.
19.7.2. Cause
<Process of this problem>
(1) Due to tolerance of DSP-IC, "Vreg OUT" voltage of some DSPs are lower than specification.
(2) If the "Vreg OUT" voltage is lower than 1.8V, internal POR (power on reset) doesn´t work.
(3) DSP can´t wake up because of no power on reset.
19.7.3. Countermeasure
Add external Regulator circuit on small PCB (with 2 cap, 3 wires) on handset to input 2.6V from outside.
65
KX-TG2248S
20 SIGNAL ROUTE
Each signal route is as follows.
66
KX-TG2248S
21 CPU DATA (Base Unit)
21.1. IC201
67
KX-TG2248S
22 CPU DATA (Handset)
22.1. IC201
68
KX-TG2248S
Click on the first or last page to see other KX-TG2248S service manuals if exist.