OKIFAX 610, Service Handbook

Page: 146 / 147

(e) The part of the secondary side
D3,D4, D5, D6, D7, D8, C12, C14, C16, C22, C25, and C18, form rectifying circuit, it transforms
AC low voltage into DC low voltage L4, L5, L6, L7, L8, C15, C17, C23, C26, and C19 to form high
fequencly filtering circuit to cause the reduction of high frequency ripple and noise.
Note: The circuit description of power supply above mentioned is mainly concerned about SNP-2866-2.
8.6.3 Indication of Eliminating Defects for TTF-2866-2
(1) When no output voltage is found, please measure the AC input first to see if any power exists or
not.
(2) When the fuse is broken, please test if DB1 and Q1-MOSFET work properly.
After you make sure that the DB1 and Q1 can work properly, then you can consider to replace a
new fuse to aboid dangers.
(3) If the Fuse, Q1, and DB1… etc. are tested with the result of working properly but the power supply
unit is still no action, it could be no action of touching-off at IC2, please replace a new IC2.
(4) If the +5V has output boltage, but one of the other outputs is found with no output, then there
might be defects in the circuitry of that single output. Therefore, the defects can be found out by
inspecting the breakdown output circuitry and then can be repaired.
(5) When using the power supply unit improperly, the status such as shorting output, burning sown the
secondary output dilde will occur and also the protection mode to the power supply unit will be
also caused. In this case, to eliminate the short position and replace a new diode in order to have
the power supply unit work properly.
(6) For the request of adj5V output voltage up and down, to add an appropriate value of
resistor at R12A then the +5V voltage can be decreased, and to add an appropriate value of
resistor at R13A then the +5V voltage can be increased.