More Microwave Madness

Work begets work.

For example; if you send an email, you’ll likely get a reply which needs actioning. Or, if you finish your work early then you’ll be given more work.

The true is same if you fix a microwave. Once word gets out about the successful repair then more broken microwaves will appear.

This Panasonic model was dead on arrival. The mains plug fuse was checked and tested good (<1 ohm resistance). Therefore it’s time to open the case.

Past experience of microwaves have shown that the majority of issues are due to blown internal fuses. These are the fast-blow fuse, more sensitive than the type in the wall plug.

The customer/client/microwave-owner had reported that their main breaker had gone a few days prior, which gave further credence to a blown fuse.

Upon testing, it was clear that the internal fuse had gone pop. Interestingly, the fuse was difficult to remove from the holder because of the “spot welds” on the terminal – must have been a hell of a surge!

Thankfully, a simple fuse change worked wonders and fixed the issue. Better still, we were able to offer the previous microwave as a courtesy microwave in the meantime.

The incoming power control board. Note small fuse.
Resistance check reading >2Mohm. ie., open circuit.

Side Quest: Petrol Pressure Washer Repair

This pressure washer came to me from storage – I’m unsure on how long it had been in storage, nor if the storage was water-tight. There was fuel in the tank, but despite my best attempts, it would not start. So began the diagnosis.

It was quickly established that there was a fuelling problem caused by a large build up of rust clogging the filter and carburettor. The rust had also turned the petrol to a funky colour.

Upon draining the petrol tank and cleaning it with rust remover, it was evident that the corrosion was endemic to the whole fuelling system, so a new carb, petrol tank and fuel lines were ordered.

Existing petrol tank before and after cleaning

These were installed along with the other general service items such as a new air filter and spark plug.

Old Vs New carb – highlighting the blocked fuel inlets

The initial test proved fruitless and a subsequent compression test yielded zero-PSI. Unsure of how far the rust had spread, a boroscope camera was used through the spark plug opening to examine the inside the cylinder chamber.

Image from inside of cylinder chamber

It turns out that when putting petrol in a new tank and carb, a bit more is needed to prime the system – so after adding more fuel the beast roared in to life.

Overall the quest was successful! The low-compression was likely due to the compression release mechanism to make starting easier.