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3. Check component by circuit tester.
1. How to check power transistors (Q701, Q702). To measure, suck
a solder from its legs completely unless faulse reading may
observe and mislead a troubleshooting. Measure across pins
between E-C, E-G, C-G, E-black lead, C-red lead of tester should
be infinite and may have some reading in reverse, it is normal.
Refer to attached table for normal reading.
2. DB701 Diode Bridge.
3. C704, C705 High voltage Capacitors. D702 and C705, D701 and
C704 are parallel connected therefore, remove component to
measure when diode is shorted.
4. D701, D702 High voltage Diodes.
4. How to replace power transistors Q701, Q702 and
Bridge Diode DB701.
1. To remove Q701, Q702 and DB701 unsolder their legs first, next
remove a screw that holding the heatsink onto the PCB then
dtach the heatsink as shown below.
Sevice Hints: For easy solder removal, use one soldering iron to
heat a solder and use solder sucker iron to suck solder.
2. Make sure to replace both Q701 and Q702 at a time with the
same maker.
3. Make sure to apply heat conduction grease between transistor
and heat sink.
4. NO DUST SHOULD CAUGHT between heat sink and power
transistor unless if causes looseness of heat conduction and
insufficient cooling to blow components.
5. Screw must be tighten securely.
6. Install the heatsink onto the PCB by a screw and
make sure to apply extra solder between legs and
PCB pattern so that it’s able to flow 15A or more
main current.
Apply silicone grease
Make sure remove inverter PCB when continuity check
Do not test component when inverter PCB is installed
FORWARD
Some
Ω
∞
∞
E-C
E-G
C-G
REVERSE
∞
∞
∞
FORWARD
Some
Ω
Some
Ω
∞
Some
Ω
REVERSE
∞
∞
∞
∞
~ - +
~ - -
~ - ~
+ - -
BETWEEN
TERMINALS
FORWARD
REVERSE
∞
infinite
Circuit tester employed
lower voltage battery
Several k ohm to several
hundred k ohm will be
observed
Circuit tester should
employed more than 9V
battery
∞
infinite
it does not matter by
internal battery voltage
A-K
HEAT SINK
Heat sink
Tighten screw securely
Clean Surface and
Apply silicone grease
Содержание NN-C781JF
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