Sharp R-8380 Service Manual page 30

1. Precautions for Handling Electronic Components
This unrt uses PMOS LSI In the Integral part of the crrcurts.
When handlrng these parts, the following precautions should
be strrctly followed.
PMOS LSI have extremely high Impedance at Its Input and
output termrnals. For this reason, it IS easily influenced by
the surrounding hrgh voltage power source, statrc electnc-
rty charged In clothes, etc, and sometrmes it IS not fully pro-
tected by the burlt-rn protection ctrcuit.
1) When stonng and transportrng, thoroughly wrap them
In alumrnum forl.
Also wrap PW boards contatnrng them in aluminum foil.
2) When solderrng, ground the technician as shown in the
figure and use grounded soldenng iron and work table.
approx 1 MR
2. Shapes of Electronic Components
Transistor Transistor
I
R-8380
SERVICING
DTD143EA
Transistor
DTAI 43ES
DTAI 14VS
DTCI 14Ei
DTB143ES
3. Servicing of Touch Control Panel
We descrrbe the procedures to permrt servrcrng the touch
control panel of the mrcrowave_oven and the cautrons you
must consider when doing so.
To carry the servrcrng, power supply to the touch control
panel is avarlable either from the power line of the oven
proper Itself of from an external power source.
(1) Servicing the touch control panel with power supply
from the oven proper:
CAUTION:
THE HIGH VOLTAGE TRANSFORMER OF THE
MICROWAVE OVEN IS STILL ALIVE TO GIVE YOU
DANGER DURING SERVICING.
[Therefore. when checking the performance of the touch
control Panel, put the outer cabinet on the oven proper
to keep
YOU
from touching the hrgh tension transform-
er, or unplug the primary terminal (connector) of the hrgh
power transformer to turn It off; and the end of such
connector shall be Insulated with an Insulating tape. Af-
ter servicing, be sure to replace the leads to their orrgr-
nal locations.
A. On some models, the power supply cord between the
touch control panel and the oven proper is so short that
they can't be separated from each other.
For those models, therefore, check and repair all the con
trols (with the sensor-related ones included) of the touch
control panel while keeping it in contact with the oven
proper.
5. On some models, on the other hand, the power supply
cord between the touch control panel and the oven
proper IS so long that they may be separated from each
other. For those models, therefore, It IS allowed to check
and repair the controls of the touch control panel while
keeping it apart from the oven proper; in this case you
must short both ends of the door sensing (on PWB) of
the touch control panel wrth a lumper, whrch brings
about an operational state that
IS
equrvalent to that wrth
the oven door being closed.
As to the sensor-related controls of the touch control
panel, their checkrng
IS
allowed If the dumrny resrstorisl
whose resistance
IS
equal to that of those controls IS
used.
(2) Servicing the touch control panel with power supply
from an external power source:
Drsconnect the touch control panel completely from the
,oven proper, and short both ends of the door sensing
switch (on PWB) of the touch control panel, which
brings about such an operational state that is
equivalent to that with the oven door being closed.
And connect an external power source to the power
input terminal of the touch control panel, and then it
is allowed to check and repair the controls of the
touch control panel; as in the case of (1)-B above, it
is here also possible to check the sensor-related
controls of the touch control panel by using the
dummy resistor(s).
4. Sevicing Tools
Tools requrred when servrctng the touch control panel as-
sembly.
1) Soldering: 30W
(To prevent leaking current, It IS recommended to use
a soldering Iron wrth grounding terminal.)
2) Oscilloscope: Srn.gle beam, frequency range: DC -
10MHz type or more advanced model
3) Others:
Hand tools
5. Other Precautions
11
2)
3)
4)
51
When turning on the power source of the control unrt,
remove the alumrnum forI applred for preventrng statrc
electncity.
Connect the connectors of the Indicator and key unrts
to the control unrt takrng care that the lead wares are
not twisted.
After alu,mrnum foil
IS
removed, take extra care that ab-
normal voltage due to statrc electrrcrty etc. IS not ap-
plied to the Input or output terminals.
Attach connectors, electrolytrc capacrtors, etc to PW
board, takrng care that all connectrons are tight.
Be sure to use specrfred components where nigh orecr~
sron
IS
required.
29