KX-TG7227UAJ, KX-TG7227UAM, KX-TG7227UAS, KX-TG7227UAT, KX-TG7228UAS, KX-TG7228UAT, KX-TGA721RUM, KX-TGA721RUS, KX-TGA721RUT, KX-TGA721UAJ, KX-TGA721UAM, KX-TGA721UAS, KX-TGA721UAT - Panasonic Telephone Service Manual (repair manual). Page 44

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KX-TG7227UA/KX-TG7228UA/KX-TGA721RU/KX-TGA721UA
9.2.
Troubleshooting by Symptom (Base Unit and Charger Unit)
If your unit has below symptoms, follow the instructions in remedy column. Remedies depend on whether you have DECT tester
(*1) or not. 
Note:
(*1) A general repair is possible even if you don’t have the DECT tester because it is for confirming the levels, such as Acoustic
level in detail.
(*2) Refer to Check Point (Base Unit) (P.44)
9.2.1.
Check Point (Base Unit)
Please follow the items below when BBIC or EEPROM or FLASH is replaced.
Note:
After the measuring, suck up the solder of TP.
*: PC Setting (P.59) is required beforehand.
The connections of simulator equipments are as shown in Adjustment Standard (Base Unit) (P.61).
Items
Check 
Point
Procedure
Check or 
Replace Parts
(A) 3.3 V Supply Confirma-
tion
VDD3
1. Confirm that the voltage between test point VDD3 and GND is 3.3 V ± 0.2 V.
IC1, C31, C32, 
R38, R39, C36, 
C37
(B) 2.5 V Supply Confirma-
tion
VDD2
1. Confirm that the voltage between test point VDD2 and GND is 2.5 V ± 0.2 V.
Q9, C70, C71
(C) 1.8 V Supply Confirma-
tion
VDD1
1. Confirm that the voltage between test point VDD1 and GND is 1.8 V ± 0.1 V. 
Q8, R72, D12, 
C64, C68
(D)*
BBIC Confirmation
-
1. BBIC Confirmation (Execute the command “getchk”).
2. Confirm the returned checksum value.
Connection of checksum value and program number is shown below.
IC7, R73, C62, 
C63, X1, C72, 
R75~R81, R62, 
R63
(E)* EEPROM Confirmation
-
1. EEP-ROM Confirmation (Execute the command “ChkTG7220XXrevYY.bat”).
XX: country code
YY: revision number
2. Confirm the returned checksum value.
3. The checksum is displayed in the last output line.
Note:
“XX”, “YY”, and “checksum” vary depending on the country version. You can find
them in the batch file, PQZZ- mentioned in JIG and PC (P.59).
IC5, C51, R62, 
R63, C50, Q25, 
R134, R141, 
C160
(F)* BBIC Clock Adjustment
CLK
1. Check X’tal Frequency. (10.368 MHz ± 100 Hz).
Input Command “rdeeprom 00 01 01”, then you can confirm the current value.
2. If the frequency is not 10.368 MHz ± 100Hz, Adjust the frequency of CLK exe-
cuting the command “setfreq xx (where xx is the value)” so that the reading of
the frequency counter is 10.368000 MHz ± 20 Hz.
IC10, C111, 
C112, X1, R73, 
C62, C63
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