For a while I have been having problems with my microwave not acknowledging that the door is closed and starting up. I have used various cludges including keeping a hand pressed on the door and using a bungee cord looped through the handle but it is becoming more difficult to find the “sweet spot” where it knows the door is latched. I decided to open it up to see if there was anything I could adjust to get better contact between the switch and latch. I failed at the stage of removing the first screw holding the cover.
I tried two different Phillips screwdrivers but they wouldn’t turn the screw, rising from the slots even when I used pressure. The screw isn’t stripped, it has never been removed before. Does this look like some specialty screw that needs a specialty screwdriver?
(Also any tips on the microwave other than “buy a new one” would be welcome. It seems far too small an issue to mean a whole new microwave.)
Looks like a standard Phillips to me. A true JIS screwdriver may give you more luck, but I doubt it. Go with a bigger screwdriver than the bigger of the two you tried. The most common mistake when using a Phillips (besides not pushing hard enough and stripping) is going too small. The right size is always a little bigger looking than you think it would be.
Hard to tell from the picture. I can’t tell if the inner part of the slot is raised or not. If so, then it’s some variant of Phillips security screw. Can you take a picture from a bit of an angle so we can tell what the inside of the slot looks like? If the inside is raised and circular then it’s a Phillips pin screw, or at least that’s what I’ve always called it. Not sure of its official name.
If the inside isn’t raised then it really just looks like a regular old ordinary Phillips screw. Phillips head screws were designed for automated equipment back in the day when automated machinery didn’t have good torque control, so the screws are designed for the driver to cam out at higher torque levels. It can be annoying as heck if you are trying to get a tight one out because your screwdriver will naturally want to cam up out of the slot.
DO NOT BYPASS THE DOOR SWITCH.
Most of the microwaves that I have seen have cheap switches that aren’t adjustable. You might need to replace the switch. A new switch should only cost you maybe $10 or so, which is a lot cheaper than a new microwave. Also, make sure that the plastic part that pushes on the switch isn’t damaged. Those are often cheap plastic and are easy to bend/break.
DANGER WILL ROBINSON!!!
Microwaves use very high voltages. There should be bleeder resistors on any capacitors which should bleed off any high voltages left inside the microwave fairly quickly after you turn it off, but sometimes those bleeder resistors fail. Be careful what you touch inside. And I hope that it’s obvious that the microwave should be unplugged while you take it apart.
Bypassing the door switch can be very dangerous. Some microwaves have security screws to stop people from bypassing the switches and potentially injuring themselves, so it’s not unreasonable that you would have security screws in yours.
Hard to tell from the pic.
Note - most microwaves have two door switches.
Nothing raised in the center, I was wondering if maybe the corners could be rounded more than usual to make getting a grip more difficult (sort of “pre-stripped”). Something inside almost but not quite makes proper contact on a normal door close. We are talking something like a mm of play. I was hoping for a plastic lever or something that I could put a couple of thicknesses of tape on.
I had to replace a switch on my microwave a while ago that started acting up. Easy enough, although getting the damn microwave out of the wall cabinet and disassembly and reassembly took a while. And I had to do it twice because of course the switches weren’t all the same part and I had to take it apart to figure out which one was bad, then do it again a week later when I got the replacement.
I did in fact break a piece of the fragile plastic framework that holds the switch in place, but was able to fix it with some epoxy and zip ties.
The best part about the whole thing was the way they were wired. My microwave had 3 door switches, and of course normally all three are open and closed at the same time. If any one of them is open, then the magnetron won’t run for safety reasons. But if two are closed and the one that started failing is open, the light and turntable will run, even if the microwave isn’t turned on. So, when that specific switch starts to fail, you get a haunted microwave that appears to turn on and start running on its own!
It took about a week of my wife thinking I was absolutely nuts before it finally did it when she was in the kitchen.
With mine, if it loses contact while running sometimes it will act as if the door has been opened normally, but other times it will stop running but the clock will continue to count down.
You might try a Posidrive screwdriver. A Posidrive looks a lot like a Phillips but there are subtle differences that make it less likely to “cam out”.
Not a good idea.
Perhaps “set” the screwdriver/screw. Insert the screwdriver and give a few whacks with a small hammer. The slight movement or shock may break a seal between the threads and whatever they are fastened into. Maybe a loctite bond or just some food or corrosion. I do this with the disc brake rotor screws and most times don’t have to drill them out.
Use an impact driver.
If this was my microwave and the door still mechanically latches, I would 100% bypass the door switch(es). At this point they’re a nuisance and proven unreliable. It’s difficult to imagine a situation (sleepwalking and glass rotation plate pillow?) where this would create a hazard. It would be different if I had a toddler in the house or something.
I do agree about the high voltage stuff. That could really hurt you in a flash.
Adding to this a bit: lots of people pick a screwdriver with a diameter roughly that of the cross shape. Intuitively, that kinda seems like it would be the right choice. But in practice, the right screwdriver may have a much larger diameter than the cross, or even the screw head itself, with only the very tip of the screwdriver going into the cross. That’s ok, and basically a design feature.
Always use the largest screwdriver that will fit at all. Anything too large won’t insert; it’ll just ride around without grabbing. Go with a screwdriver just one size below that point.
Switches vary, but most of the ones that I have seen have a little plastic button on top that gets pushed down. Tape probably isn’t going to work.
Here is a typical switch if you want to see why. The little red button on top is the part that pushes down and activates the switch. The “fingers” on the door need to be able to move over this button smoothly.
https://www.amazon.com/ERP-28QBP0495-Microwave-Door-Switch/dp/B002CRSOR0
Internally, the switch is usually a lever action, and if the plastic “finger” that activates the switch on the door (and latches the door closed) isn’t damaged, it’s often the lever that wears out due to simple metal fatigue. If you can take the switch apart you might be able to bend the lever part so that it raises the button on top a bit, but if you are fighting metal fatigue this probably isn’t going to last long. You can also try pulling up on the little red button, but often it’s just a floating piece of plastic and isn’t attached to the metal lever inside the switch. If it is attached to the lever inside then you might be able to bend the lever up a bit, which might accomplish what you want.
IIRC a Japanese Incompatible Screw will have a “dot” stamped into the screw head. This might be just a cheap screw with an improperly formed cross. Absent any other identifying markings there’s a slim chance it’s a Reed & Prince screw.
You shouldn’t try pozidriv drivers because using a phillips head driver could damage your screw heads?
Generally, it’s best to use the correct driver for the correct screw, but in a slightly rounded-out phillips head, a pozidriv sometimes works better. Because it’s not as pointed, it doesn’t bottom out as fast, and can actually engage the screwhead better than the correct sized phillips driver. If you push it in far enough to engage the ribs, engaging the ribs may damage the head, but actually helps turn the screw.
A solution to damaged phillips head screws is to cut a slot with a hacksaw.
Cross=head screws that aren’t phillips head are mostly supposed to be marked: pozidriv, supadriv, JIS etc, and cheap screws that aren’t marked are mostly, more or less, phillips.
Most of the time, but not always. I brought up JIS because in threads like these, someone will come along and mention trying a JIS screwdriver in a Phillips, and there usually isn’t any more luck. Most screwdrivers sold as JIS screwdrivers aren’t true JIS and closer to Phillips anyway. Reed and Prince is different than JIS. I’ve never seen it used in appliances or electronics.
How did you wind up with that interpretation? What I quoted clearly says using a Pozidriv screwdriver could damage a Phillips head screw. I’ve tried putting them on Phillips screws in desperate times and they never fit right, hence me finding a cite that agrees. There are many more. Pozidriv screwdrivers do not fit Phillips heads snugly and Phillips heads strip too easily to even try, IMHO.
You could always use one of these:
Screw extractor
I’ve not used this particular product, but have used one sold under the Craftsmen name for a few years.
The fastener could have loctite on it, if backing out was an issue and it’s not intended to be serviceable. Generally if it’s camming out you just need to push in harder as you turn, or use an impact driver, but you may damage the microwave with that.
I should probably also mention that you need to make sure that this is a screw that actually needs to come out. There have been a few idiots (like me, ahem…) who removed a screw thinking that it held the case on when it actually held the magnetron in place. Oops.
Some microwaves can be a bit tricky to take apart. For example, sometimes there’s a single screw on the bottom that holds the control panel in place. Remove that screw, and the control panel lifts up and out (aside from the screw it’s only held in by metal tabs). Once the control panel is out, THEN you can finally see the screws you need to remove to get to the switches.
YMMV (your microwave may vary)
You might want to google disassembly instructions for your specific microwave. Some are straightforward, but some of them are like little puzzle boxes.
I’ll come at this problem a different way - if the door is indeed detected as closed if you press it shut while operating the microwave, doesn’t that indicate that the problem may not be with the switch sensor sensitivity but the door itself? Like, it’s legitimately slightly ajar if you don’t press it shut. And the easier fix than disassembling what may be a component that is not designed to be serviceable, is to tighten the hinges on the door, or even to replace the door if you can get it as a replacement part (new or salvage).