Panasonic KX-FT21BX Service Manual page 101

(2) Troubleshooting flow chart
Our recommendation for troubleshooting is as follows.
This procedure comes from our experience of troubleshooting in our lab.
* Before turning on the power supply, you should check F101.
ls F101 open?
Replace F101.
D101-D104 is short.
Replace D101-D104.
D-G, D-S,
S-G (Q101) short?
Replace Q101.
24V output OK?
NO
Does D105, D106, D107,
PC101 or Q102 short?
Replace the broken part.
24V output OK?
NO
YES
NO
YES
NO
YES
YES
NO
(Control circuit check)
YES
YES
A
NO
A
5V output OK?
Replace IC202.
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KX-FT21LA
NO