Microwave Switch Replacement? - Page 1
Forum section: electronics / repair

author: smorello
author_rank: Newbie
timestamp: November 13, 2023, 08:18:37 pm
content: Hi all,Newbie here. My microwave has been acting up and I've been trying to fix it by replacing the interlock switches. I was able to find replacements for 2 out of the 3 that need to be replaced, but the one that's got an actual wobbly contact seems to be hard to find (I found it on eBay but would take at least a week to get here) so I'm wondering if someone can help me figure out:The wobbly one (link here for referencehttps://www.certified-parts.com/microwave-door-latch-locks-interlock-switch/microwave-normally-open-no-door-interlock-switch/gsm-v0303a2-sharp-microwave-door-interlock-switch-normally-open-gsmv0303a2) is rated for 0.3A 24VDC . I have an extra one (link for referencehttps://www.amazon.com/LONYE-SZM-V16-FD-63-Microwave-Replacement-Normally/dp/B082HZ1H47/ref=sr_1_2_sspa?crid=2J42N3Z7V4O9S&keywords=SZM-V16-FD-63&qid=1699904361&s=appliances&sprefix=szm-v16-fd-63%2Cappliances%2C221&sr=1-2-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&psc=1) that's rated 0.6 125VDC /0.3A 250VDC.Can I use the latter to replace the former since they are both NO and the latter is rater for a higher voltage?If not, can I just replace the copper flap that's causing the wobbliness on the former with the flap from the latter?

author: amyk
author_rank: Super Contributor
timestamp: November 14, 2023, 12:17:47 am
content: Are you sure it's the switches which are the problem?These are a standard form factor and widely available from various manufacturers.In older microwaves they were all mains-rated switches in the magnetron power circuit, but perhaps yours is one of the newer models with additional low-voltage switches that only provide a signal to an MCU.Normally it should not be a problem to use a switch with a higher voltage rating.

author: ploxiln
author_rank: Contributor
timestamp: November 14, 2023, 04:44:35 am
content: My microwave had the same problem, failing door switch. At first I didn't know what it was - it would trip the circuit breaker whenever trying to actually start heating, and I assumed that meant something was shorted inside, maybe a couple capacitors went bad ... (very) long story short, it was the door switch interlock, arc-welded closed. (I actually had to have 2 replacements fail the same way, before I figured out exactly what was wrong with them, and thus how it happened ...)So on mine, it's the middle switch, NC (normally closed), the other two switches (top and bottom) are NO (normally open) and those have been fine. I've been able to find acceptable replacements on Amazon, "KW3A" switches rated for 125 VAC 10A (I'm in the US).The problem is caused by yanking open the door while the microwave is running. I assumed this was OK to do, and I've done this for decades with different microwaves. But my previous microwaves had a big button you would depress like half an inch, that would turn off the power _before_ kicking open the door, which would disengage the NC interlock switch, which I guess shunts the power to ground when the door opens. But the one that came in my latest apartment just has a handle on the door, and when you pull it open, all switches deactivate very close together, both the ones that tell the mcu to turn off the power, and safety interlock that shunts to ground. So perhaps after some years the door hinge has sagged a bit, the door hook guide in the frame has worn a bit, and the timing is a bit off, so when you yank the door the interlock closes a millisecond too soon, you get an arc of power though it, your breaker trips, and that switch welds itself closed. So after resetting the breaker, and trying to use the microwave again, it trips again just trying to start, before you've done anything "wrong".I hope my personal microwave saga (omitted for brevity) has finally helped someone