File: SM1280_r7eng - April 2017 - Technical note: SM1280
page 25 of 27
SM 1280
SM 1280
ALARM TROUBLESHOOTING
Code
Description
Cause/Solution
01
Magnetron Over
Temperature
a) Check water flow and incoming water temperature
b) Check magnetron thermoswitch (contact grounded=OK,
open=alarm)
c) Check setting of magnetron thermocouple: if latter isn’t
present the alarm threshold must be set = 0
d) Check air flow.
e) Excess of reverse power. Reduce power,
02
Rack Over
Temperature
a) Check for restrictions to the air flow
b) Eliminate air recirculating between outlet on the sides and the
rear inlet
03
Arc Detected
Electric arc in waveguide.
If arc detector isn’t used, the related input must be grounded.
If used, contact grounded=OK, open=alarm
On alarm, check waveguide and magnetron antenna status.
Check Arc detector wiring.
04
Over Current
An excessive current has been detected, or a dangerous
temperature is present into the unit.
a) Check air flow blocks.
b) Eliminate air reflow between side entry and rear output.
c) A short circuit is present on H.V. cable: check wiring.
05
Over Voltage
a) The high voltage connection is open
b) Magnetron may be moding
c) The high voltage connectors are not fully inserted: if true
check for h.v. spot discharge inside socket/plug: in case replace
them.
d) The filament is cold: check filament current with high voltage
OFF (=enable signal OFF, h.v. connector #3 disconnected)
Check filament transformer wiring and compliance.
e) Verify preheating timer checking how many seconds require
the “READY” led to become ON stable: if you feel too short try
to enable the unit (= enable MW ON) only 10 seconds after
enabling the filament (if the command is available) or after
general power ON (when the filament command is always ON)
f) check the filament timer (with the FrontPanel program from the
PC): set >10 seconds.
As soon as an alarm is generated, the microwave output is
immediately stopped, the alarm relay contact opened, the
alarm code relay contacts set to the appropriate values, and the
red LED on the unit panel is lighted (or if the LCD is present
on the front-panel of the unit, a proper warning is displayed)
Also the interlock relay is opened, and no voltage is routed to
the head.
When the cause of the alarm is removed, the red LED is
switched off, but the alarm condition is latched, and can be
reset only removing the hardware ENABLE input for at least
2 seconds.
As the filament has been shut down, the preheating time has
to be waited after any alarm, before being ready to output
microwaves again.
The following table can help to locate and remove the alarm
condition:
Summary of Contents for SM 1280
Page 2: ...Cover Rear...
