Panasonic
Number: E10-2010-06
Technical Bulletin
Date: July, 2010
Panasonic Home and Health Company
Home Appliance Group / Food service
Product: Commercial Mircowave Oven
Model:
NE1257R, NE1258R, NE1757R,
NE2157R, NE2180, NE3280
Subject: Magnetron Test for Opens, shorts or Insufficient Power
A. The following tests will indicate if a magnetron is open or shorted
.
•
Unplug the unit
•
Discharge all the H.V Capacitors (refer to service manual on how to discharge)
•
Disconnect all the leads (connectors) from the magnetron terminals.
B. The following temperature test will indicate if a magnetron is weak. Make
sure unit is plugged in.
1. Fill a beaker or cup with
EXACTLY
8 oz (1 Cup) tap water.
2. Record the temperature of the water (Should be approx. 70
o
F)
3. Place it in the center of the microwave and heat it for the time specified*.
4. Water should be boiling. Record the temperature again.
5. Temperature should rise approximately 142
o
F (Go to Step 6 only if temperature rise is
considerably lower than 142
o
F otherwise all magnetrons are functioning properly)
6. To test for the weak magnetron, connect one magnetron at a time and repeat Steps 1-4.
a. For ovens that contain 2 magnetrons (NE1257R, NE1258R, NE1757R, NE2157R), the
temperature rise should be approximately 70
o
F per magnetron.
b.For ovens that contain 4 magnetrons (NE2180, NE3280), the temperature rise should be
approximately 35
o
F per magnetron.
* See field expedient test on the back of the page
Step 1
•
Using an Ohm meter on its lowest resistance scale, measure the
resistance from one magnetron terminal to the other in either direction as
shown on the illustration on the left.
•
Meter should read less than 1
Ω
indicating that the filament is good.
•
If Filament checks good, proceed to Step 2
Step 2
•
Using an Ohm meter on its highest resistance scale, measure the
resistance from one of the magnetron terminals to the metal casing of the
magnetron as shown on the illustration on the left.
•
Meter should read infinity (open circuit)
regardless of meter polarity.
If the meter indicates a short (Less than 1
Ω
), the magnetron is defective.
