Panasonic Microwave NN-A554?

i try to set clock ',then when i set heating time i
cant it it won't press pad

rosh george
June 2016

Wow....how clever are you??!!

I have printed you answer to see if my partner can follow you well written instructions!

I just appreciate your time and knowledge....we'll let you know how we get on.....thank you again Nick
Kind regards
Jules

Jules
April 2011

It sounds as though a heat operated trip is kicking
in to protect the circuits.There are some checks that
you can do if you have a test meter and feel confident.
Set the control to low heat and listen for the on /off
switching of the magnetrons hum.If present with no heat it is likely that the magnetron has a burnt out emission electrode.
This is evident at the output tip by burnt and blackened metal.This indicates that a new magnetron will be required.The magnetron contacts should show low resistance between the two and infinitely high resistance to earth.Alternatively if the magnetron looks intact and has a healthy hum ,check that the transformer is not getting hot.It should be no more than warm.With the machine disconnected from the mains you can do some continuity checks on the transformer primary and secondary windings.Also check for shorts to earth.
If no magnetron hum present and transformer readings are good(ie both windings less than 200 ohms)you might try next to check the voltage output from the transformer secondary.You will need to set the meter on a 1000volt scale as the voltage at that point will be 400+ volts.You should disconnect the capacitor
before doing this.The capacitor and associated high voltage diode wind up the voltage before output to
the magnetron and would give you a nasty nip even when the mains is disconnected.If voltage at the secondary output is good chances are the diode has blown.The capacitors are usually fairly reliable,and I would suspect that last.Both these last two are not testable without specialist equipment and are best eliminated by substitution.
This is not an exhaustive diagnostic obviously but as with all such equipment there comes a point where
you have to ask if it is worth the hassle to continue.Replacement parts are often expensive and the machines are not that dear to buy.Diodes from another machine usually work but transformers and magnetrons are a bit more specific to each model so that you need to be sure of your diagnosis before splashing out.
Hope this helps.

nick
April 2011