UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Microwave oven repair

Pilot Mariner · 28th Jul 2020, 9:42 pm

This sounds similar to the Panasonic MW oven as mine which failed last week after 15 years of service.

I also attempted to repair it. I found getting into the oven was fairly straight forward after realising that the cover slides back after undoing the rear screws.

I couldn't find any faults on the inverter unit so I turned my attention to the control pcb which was a real pain to remove from the front control panel.

As can be seen on the picture, the tiny diode D29 (best seen on the print side) serving as a half wave rectifier taking full mains voltage from CN1 to the electrolytic capacitor, had shorted out. This had blown a track, the TOP2?? switcher IC and consequently the micro-controller IC. Sadly I could not find a replacement control pcb and in any case similar pcbs were in excess of £60.

I ended up splashing out on the new equivalent Panasonic MW oven (NN-CT55). However I am surprised that Panasonic being one of the upmarket brands would use such a crude power supply circuit.

28th Jul 2020, 9:42 pm	#2
Pilot Mariner Hexode Join Date: Jun 2003 Location: Burntwood, Staffordshire, UK or Kabaty in Warsaw Poland. Posts: 439	Re: Microwave oven repair - aggravations, warnings and questions This sounds similar to the Panasonic MW oven as mine which failed last week after 15 years of service. I also attempted to repair it. I found getting into the oven was fairly straight forward after realising that the cover slides back after undoing the rear screws. I couldn't find any faults on the inverter unit so I turned my attention to the control pcb which was a real pain to remove from the front control panel. As can be seen on the picture, the tiny diode D29 (best seen on the print side) serving as a half wave rectifier taking full mains voltage from CN1 to the electrolytic capacitor, had shorted out. This had blown a track, the TOP2?? switcher IC and consequently the micro-controller IC. Sadly I could not find a replacement control pcb and in any case similar pcbs were in excess of £60. I ended up splashing out on the new equivalent Panasonic MW oven (NN-CT55). However I am surprised that Panasonic being one of the upmarket brands would use such a crude power supply circuit. Attached Thumbnails