Panasonic KX-FT21BX

-9-
(Model KX-FT21BX/KX-FT21BX-W)
KX-FT21BX/KX-FT21BX-W
24V output OK?
Replace the broken part.
Are D201, IC201, PC101
and R222 OK?
YES
NO
YES
NO
Replace the whole board.
A
24V output OK?
Are R108, D108, R125
and D107 OK?
NO
YES
Replace the broken part and IC101.
YES
NO
(Control circuit check)
A
Power ON
Power ON
Power OFF
Power OFF
Broken parts repair details
(D101, D102, D103, D104)
Check for a short-circuit in terminal 4. If D101, D102, D103 and D104 are short-circuited, F101 will melt (open).
In this case, replace all of the parts (D101, D102, D103, D104, F101).
(Q101)
The worst case of Q101 is a short-circuit between the Drain and Gate because damage expands to the peripheral
circuit of Q101.
This is due to a very high voltage through the Gate circuit which is composed of R107, R109, D106 and IC101.
You should change all of the parts listed as follows.
F101, Q101, R107, R109, D106, IC101
(D201)
If D201 is broken, the oscillation circuit in the power supply cannot operate. Check it with an electric tester.