Test Procedure - Panasonic NE-7910 Service Manual

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COMPONENT TEST PROCEDURE
Normal readings should be as follows:
HIGH VOLTAGE TRANSFORMER
FILAMENT
TERMINALS
Secondary winding ............. Approx. 502 ~ 700,
Fil twinding ..........800% A .02
PROGRAMMER ==TERMINALS
TERMINALS.
Oven chassis
(Fig. 38)
High voltage capacitor
Check continuity of capacitor with meter on highest OHM scale.
A normal capacitor will show continuity for a short time, and then indicate open once the capacitor is charged.
A shorted capacitor wil! show continuous continuity.
An open capacitor will show open or infinite resistance.
Resistance between each terminal and chassis should be infinite.
Diode
The-diode is iocated on the base near the transformer.
Isolate the diode assembly (diode and varistor) from the circuit by disconnecting the leads.
With the ohmmeter set on the highest resistance scale, measure the resistance across the diode assembly terminals.
Reverse the meter leads and again observe the resistance reading. Meter with 6V, 9V or higher voltage batteries should
be used to check the front-to-back resistance of the diode, otherwise an infinite resistance may be read in both dire-
ctions. A normal diodes' resistance will be infinite in one direction and several hundred KQ, in the other direction.
Magnetron
For complete magnetron diagnosis, refer to "Measurement of the Magnetron's output' (page 23).
Continuity checks can only. indicate an open filament or a shorted magnetron. To diagnose for an open filament or
shorted magnetron.
Isolate magnetron from the circuit by disconnecting the
leads.