View Sharp R-85STMA (serv.man8) Service Manual online
reading of less than 1 ohm.
test should be indicated an infinite resistance. If a low or zero resistance reading is obtained then the magnetron should be replaced.
Sharp Technical Training notes which is available from Sharp Parts Centre (part number SERV-LITMW01).
cal Training notes (part number SERV-LITMW01). The maximum leakage permitted in BS EN 60335-2-25 is 50W/m
should be obtained:
(thermal cut-out) indicates overheating of the high voltage transformer. Check for restricted air flow to the high voltage transformer, especially the
cuits, including the magnetron filament.
Connect the ohmmeter across the terminal B+C of the high voltage rectifier and note the reading obtained. Reverse the meter leads and note this
second reading. The normal resistance is infinite in one direction and more than 100 k
tested using an ohmmeter set to its highest range across the terminals A+B of the asymmetric
rectifier and note the reading obtained. Reverse the meter leads and note this second reading.
If an open circuit is indicated in both directions then the asymmetric rectifier is good. If the
asymmetric rectifier is shorted in either direction, then the asymmetric rectifier is faulty and must be replaced with high voltage rectifier. When the
asymmetric rectifier is defective, check whether magnetron, high voltage rectifier, high voltage wire or filament winding of the high voltage transformer
and C3 of the thermistor harness.
in the below.
inside the oven.
between the terminals as described in the following table.
parts or repair the wire harness.
nals of the heating element as described in the following table.
temperature is approx. 20
500V - 100M
tenance can not be performed with only a voltmeter and ohmmeter.
units, CPU unit and Power unit, and troubleshooting by replacement is described according to the symptoms indicated.
trol unit is faulty.
depressed, first verify the ribbon cable is making good
contact, verify that the stop switch operates properly; that
is the contacts are closed when the door is closed and
open when the door is open. If the stop switch is good,
disconnect the flat ribbon cable that connects the key unit
to the control unit and make sure the stop switch is closed
(either close the door or short the stop switch connector).
Use the Key unit matrix indicated on the control panel
schematic and place a jumper wire between the pins that correspond to the STOP/CLEAR pad making momentary contact. If the control unit
responds by clearing with a beep the key unit is faulty and must be replaced. If the control unit does not respond, it is a faulty and must be replaced.
If a specific pad does not respond, the above method may be used (after clearing the control unit) to determine if the control unit or key pad is at fault.