Microwave oven door switches?

[ForumUser1]

Hi All,

Not exactly center of this group's interest, but thought I might get lucky!

Five year old, very expensive Kitchenaid (Whirlpool) convection/microwave oven mounted above stove.

Have replaced the brackets that hold the door switches, and that worked for awhile, but now same indication of door open/close, so after reviewing a lot of threads and videos, I think it is likely ONE of the THREE switches - while each has a different part number they all appear to be the same function - either single or double switch. Three connector locations - one switch uses all three pins (two sets of points), and two switches have single points, one normally closed and one normally open.

One fellow's video (

) showed how he swapped out all three to the same Omron switch, simply using the correct two of three connectors on the single point switches - he didn't specify an Omron part number, though.

I'm having trouble finding which Omron switch to use ... anyone have idea how to do this?

Thanks!

 

[rjenkinsgb]

They appear to be common "V3" type microswitches, without any additional actuators. They are available in various current ratings - the highest appears to be 16A rated.

eg. Omron D3V-16G-1C25

D3V-16G-1C25 | Omron Pin Plunger Micro Switch, Tab Terminal, 16 A @ 250 V ac, SPDT, IP40 | RS

uk.rs-online.com

https://www.mouser.co.uk/ProductDetail/Omron-Electronics/D3V-16G-1C25?qs=cV4tcm38%2Fl9K2bnFYqS1wA%3D%3D

https://www.digikey.co.uk/en/products/detail/omron-electronics-inc-emc-div/D3V-16G-1C25/1789291

 

[ForumUser1]

Here's best photo I have of one of the switches from when I last disassembled - it is the FC-62 version ... looks like a 16A?

 

[ForumUser1]

Yeah - here's what I think is a "kit" approach - can see the difference between the normally open and normally closed using different terminals. No idea of quality, though.

Here's photo of the last time I had it apart - switch just fell apart - looked OK inside, though and worked until just recently ...

 

[ForumUser1]

So, I should be able to use the same Omron D3V-16G-1C25 for all three switches - match wiring for the three wire (SPDT), and then note which terminal for the differences between the normally open and normally closed.

I'm assuming appliance companies specify which terminals to remove in order to mitigate appliance repair folks switching wires and potentially frying the microwave?

Here are some snips from the video ... so, could leave exactly as they are and use correct terminals, or, pop open and remove the terminal not needed?

 

[ForumUser1]

Finally found spec sheet - the D3V-16G-1C25 is the basic SPDT, the -2C25 is the Normally Closed (NC) and the -3C25 is the Normally Open (NO) - again, it looks like one could simply use three -1C25 switches, one for the three terminal ((SPDT), and one each for the the SPST-NC and SPST-NO switches (matching the pin out).

 

[rjenkinsgb]

it looks like one could simply use three -1C25 switches, one for the three terminal ((SPDT), and one each for the the SPST-NC and SPST-NO switches (matching the pin out).

Yep, that should work fine.

An appliance manufacturer buying them by the thousands may be able to save money and/or reduce assembly confusion by omitting the unused terminals, but for repairs the basic three terminal switch is the likely the best option.

I would definitely not remove anything from the switch - that would change the contact travel distance and possibly mess up the switch over-centre operation, so it could stick open.

You could put a bit of heatshrink sleeving on any spare terminals, to avoid confusion in the future if it's ever worked on again.

 

[ForumUser1]

rj,

Thanks - great idea on heat shrink! I may do that in advance to prevent wiring backwards!

Any supplier/manufacturer product you like better than Omron? I've already ordered through Mouser, but jic for the future!

 

[rjenkinsgb]

I'd stick with Omron or one of the other big, long-term companies - and only buy from a major distributer, as there are many counterfeit or reject parts on market sites like amazon, aliexpress & ebay.

They are OK for experimenting & non-critical stuff, but I would not chance them is a safety related application.

We mainly use Schneider (formally Telemecanique), Siemens & Omron gear for serious work.

 

[Nigel Goodwin]

As someone who spent decades professionally repairing microwave ovens, we always obtained the correct parts from the manufacturers (although it's not usually an option unless you're a manufacturers service agent).

This is because it's possible that the different switches may be designed to actuate slightly differently, in order to give a certain timing sequence. Also, the switches have entirely different purposes, with one of them used to directly short out the supply in case the other two switches fail - so an entirely different type of action. Often the switches look functionally identical, but have different part numbers on them.

In the UK there are also strict rules about the repair (and supply of parts) of microwave ovens, anything which requires the top removing should only be done by an authorised engineer, and the oven must be power and leakage tested afterwards - not with a 'toy' leakage detector (like the public can buy), but a professional one, which also has to be sent away annually for testing and calibration.

 

[ForumUser1]

Well, my initial order with Mouser is a bit more complicated. The initial image of the D3V 16G showed actuator pin then the order showed a long metal arm on one and a standard pin on the other. Do ya think the arms removable based on the application?

Edit - looks like they are shipping the correct ones!

 

[ForumUser1]

Nigel - all good points! Thanks.

 

[ForumUser1]

Just did a quick read on microwave oven leakage.

- Microwave ovens leak some amount
- There are maximum leakage standards from many federal governments
- Microwave oven radiation is around 2.45 GHz and is non-ionizing
- Leakage is usual through gaps in shielding, mainly the door, hinges, etc (logical)
- Some governments mandate certifications for repair of microwaves

 

[Nigel Goodwin]

Just did a quick read on microwave oven leakage.

- Microwave ovens leak some amount
- There are maximum leakage standards from many federal governments
- Microwave oven radiation is around 2.45 GHz and is non-ionizing
- Leakage is usual through gaps in shielding, mainly the door, hinges, etc (logical)
- Some governments mandate certifications for repair of microwaves

As far as I'm aware most countries have standards for microwave oven leakage etc, and usually restrictions on who repairs them, for obvious safety reasons.

The USA has stricter leakage regulations than the UK, but having tested thousands of ovens here in the UK I've only ever found two which leaked at all, and those were still within permitted UK limits. They were both identical Philips models, where the doors hinged downwards (stupid idea or what?), and only latched at the top RH corner, so both had slight leaks from the top LH corner

One of my work mates went on a microwave oven service course, and as part of the course the instructor made a hole in the middle of the door, and tore the mesh inside apart - leaving a gap about an inch across. They then leakage tested it, and it passed

 

[JimB]

he instructor made a hole in the middle of the door, and tore the mesh inside apart - leaving a gap about an inch across. They then leakage tested it, and it passed

Not surprising.

The average microwave oven runs at about 2400MHz, a wavelength of 12.5cm.

The hole in the door was 2.5cm wide, significantly smaller than the wavelength of the microwave energy.
Hence very little leakage.

Another thing about microwave oven doors, they don't make electrical contact with the body of the oven.
They have what is called a "choked flange" in a waveguide system.
There is a slot in the door which makes a quarter* wavelength long slot which effectively creates a short circuit at the frequency of the oven.

* Or is it half a wavelength? I cant remember of the top of my head.

But it certainly does not relay on a good low resistance contact as would be needed for the door of a screened room. ie a wide frequency range Faraday Cage.

JimB

 

[Nigel Goodwin]

Another thing about microwave oven doors, they don't make electrical contact with the body of the oven.
They have what is called a "choked flange" in a waveguide system.

In microwave oven terms it's called a 'choke seal' - very old ovens didn't have it.

 

[ForumUser1]

Completed repair - thanks for the advice and help!

Very nice Kitchenaid Convection/Microwave!

I previously replaced the plastic components that rotate and actuate the switches … worked for awhile, but then tenants never told me when stopped working.

So, all three switches fell apart as I was handling them … really AWFUL quality. But, the Bottom Right (FC-63) … fell COMPLETELY apart - and, the contact on the moving arm looks burned - as does the matching fixed points side. Given it was the most clearly burned, and even the constituent pieces became detached (the copper colored one is a tensioner (I think) to return the points to open when the button is not detented by the rotating cam), I’m figuring this was the real culprit.

Photo shows the likely culprit replaced (replaced all of them, though) … with Omron generic commercial quality switches. These even seem a bit heavier (don’t have scale). Red heat shrink is to insulate and remind where the wire goes.

 

[Tony Stewart]

Bakelite plastic does that awful thing with aging.
- phenol (derived from coal tar) and formaldehyde (derived from wood alcohol)

 

[ForumUser1]

Oven is from 2016.

The cases on these look absolutely perfect - in addition to whatever the cause of the pitting and failure internally, the cases are held together only by two pins - no adhesive, which although I know zip about these things, seems a bit off from design standards related to switches that are not repairable.

Of note, some of the videos on this manufacturer's microwaves have two of the black plastic China switches, but the DT switch was a China Honeywell in gray plastic.

 

[christinescoms]

As someone who spent decades professionally repairing microwave ovens, we always obtained the correct parts from the manufacturers (although it's not usually an option unless you're a manufacturers service agent).

This is because it's possible that the different switches may be designed to actuate slightly differently, in order to give a certain timing sequence. Also, the switches have entirely different purposes, with one of them used to directly short out the supply in case the other two switches fail - so an entirely different type of action. Often the switches look functionally identical, but have different part numbers on them.

In the UK, strict regulations govern the repair of microwave ovens, emphasizing that tasks involving the removal of the top should solely be performed by authorized engineers. Similar attention to detail is required when choosing adorable baby frocks—seeking quality and safety ensures your little one's comfort and style.

Any idea where I can find a door switch for a Goldstar microwave? I tried Sears, as they handle some Goldstar parts, but they came up blank on that model number.