I don't know about the rest of you, but there's always something around here that needs to be fixed. Most of the time it's something I've never tried to fix before and frequently something with no electronics content - what I consider my "home field advantage".
This week ended up being broken vacuum cleaner week. I've never had one broken vacuum cleaner to fix in my life; this week I had two. As it turned out, they were both electrical problems, which helped.
The first one was the carpet attachment for our house cleaner. It's not this model Panasonic, but the same basic concept: there's a canister with the dust bag, power on/off switch and a connector for the hose to plug into. The hose has wires embedded in it that brings the power to carpet attachment.
On Sunday, Mrs. Graybeard got the thing out to clean our couple of throw rugs and the carpet attachment wouldn't turn on. Before going too far into the whole assembly, she opened up the carpet attachment and verified that the belt was good. I eventually came over and volunteered to dive in. We verified that everything in the beater was wired up and motor seemed good, so now we're down to the main vacuum or the hose. We quickly isolated it to the wires that run down the hose, and eventually bring power into the carpet beater. There are two wires, one was open from end to end.
It took more time to take it apart because there are single piece molded plastic parts on both ends. On the vacuum cleaner end, there's a rotary joint, so the hose can spin around. On the handle end, it just ends in the handle, which has a switch. A wire had pulled out of its connector in the end of the hose nearest the handle. Aside from a piece of duct tape to hold together a rubbery plastic elbow that I cut open to inspect the wires (visible in the picture at the top of the hose, going into the connector on the body), it's just as it was before the wire pulled out.
Once that was fixed, on Wednesday I went to turn on my Shop-Vac to clean up some chips and residue on the lathe (where I'm working on the cylinder for my flame eater engine). The Shop-Vac didn't turn on - I had used it the day before. Putting an ohmmeter across the AC plug, I could see the motor never got connected. Now it's down to the motor, the power switch or the power cord. I started looking for a circuit breaker or fuse or something. Nothing found.
After some research online and YouTube, I found that the motors in Shop-Vacs have some sort of fuse attached to the motor with a molded plastic holder. With a couple of videos watched, I went and tore down the vacuum until I could hold the motor in my hand. Sure enough, the fuse was open. Only it's not a fuse. After unsuccessfully trying to find one for this specific model Shop-Vac , I found that the thing is built in an amazingly crude manner. See that little yellow square?
This is a pic from online, not from mine, but it looks exactly like mine. The orange wire goes to the power switch and the copper wire goes to a stator on the motor. Inside the yellow plastic piece, it has two sorta V-or U-shaped spring clips
that you shove the flat terminals under (these are crimped onto
the orange and copper leads) and these clips ride on what looks like a short
piece of wire. Only it's not wire, it's solder. That's right: when
the motor draws too much current, the solder melts and disconnects the
power. Looking at the terminals in mine, it's hard to see how it could
not work, since only about an eighth inch (or less) of solder wire looks
like something other than pristine wire.
I spent my entire career in high reliability electronics and I know that influences my thinking, but when I understood what they were doing, I was appalled. Think of the numbers of Shop Vacs that get thrown out because a little piece of solder (fusible link) opened and there's really nothing substantially wrong with the motor. For some reason, the motor drew too much current and blew the fuse. If it was a real circuit breaker, maybe add a buck or two to the cost, you could just press a button and reset the fuse. Maybe let it cool down, first. Heck, letting it cool down overnight makes more sense than using a piece of solder and throwing it out when it opens.
Better yet, a thermal fuse that opens if it overheats and then resets itself when it cools down enough.
Shop-Vac has a warranty, and I read that if you had proof of purchase and contacted them, they'd send you a new motor. Otherwise the motor cost what a whole new Shop-Vac costs.
I spent a lot of time agonizing over this, because I don't really have numbers on what the "fuse" needs to do. I could put a piece of solder in there and call it a fuse. I
could put a piece of copper wire in and call it the fuse. Maybe the solder
is 20 ga. wire while the copper would be 30 ga,. At some point either
one will melt. Whether that's before or after the vacuum catches fire is something I can't answer.
I eventually just dialed up a bit of "you're over complicating things", found the thickest solder I have, wound a double strand of it (to approximate the original's size) and put the vacuum back together. Works like a charm. I used it a half dozen times today, a few seconds to maybe a minute at a time.
Will it hold up? Time will tell.
Well,look at it like this- who ever leaves a vacuum cleaner running unattended? So smoking the vac is an isolated disaster-not like it will burn down the farm or something.ReplyDelete
I fully understand the 'shortcuts' taken in high-volume are appalling to you. I've been on both sides, and sometimes the things seen in "consumer electronics" make me cringe, too. As you surmise, there are better solutions that only cost a buck more, and that's what *I'd* use in a product like that.ReplyDelete
BUT.....if they sell 500,000 shopvacs, that's $500k added to their bottom line, and to some companies, that matters more.
Maybe a YouTube "how-to-upgrade-and-fix" video would be nice for the zillions of us out there who lack your knowledge base and talent. I know that I would personally benefit from something like that. Unlike DRJIM and you, I'm a solid dunce in such things and need tutorials to bridge the gap between desire and capacity in setting such things right.Delete
Jim - BTDT. I never worked in high volume commercial, where saving a fraction of a cent on a part you buy millions of adds up to real money, but I've sat through the "we're building a Chevy not Rolls Royce talk" many times. (There are some moderately funny stories down that road, too, but not today).Delete
I suppose their answer to the $1 part is that they'll sell you a "service plan" that replaces your appliance if it dies for another $25.
FWIW, and for posterity, I read that Ridgid's wet/dry vacuums use an actual thermal cutoff fuse, Thermodisc brand. Even found a part number (although I don't know what model it's for). It's actually designed to be replaced. If this one goes, I'll probably replace it with a Ridgid.
LL, considering the place I go first to figure out how to fix stuff is the web and YouTube, that's a good idea. This info is there, but it's hard to find the information you're looking for.
Yeah, I've had to give the "it's not going to the Moon, BUT..." talk a few times in my career.Delete
From observation, it's obvious that the higher volume of production, the more they look at the total cost, and not to the cost of the item itself. Auto producers are notorious for this type of thinking, arguing over a 25cent part.ReplyDelete
Save a penny per part on something you buy 10,000 of and you save $100. Save a penny per part on something you buy a million of and you save $10,000.Delete
If they're both over the same time period, nobody questions saving the $10,000.
Not sure if they still do so, but cars have traditionally had fusible links in the wires leading from the battery. And those are even worse than your ShopVac. Especially if one gets funky whilst you are in the wrong part of town...ReplyDelete
A fusible link on a battery that big is really a good idea. Those things will melt a wrench in half - if they don't explode first.Delete
When you consider that a shop vac is picking up dust, and sawdust, which is not just flammable but explosive, it's a good idea there, too.
A fusible link that's not replaceable is bad idea anywhere.
But those fusible links in the battery cables are also not replaceable without replacing the entire cable...Delete
Question from the ignorant reader section (waving hand in the air, teacher! teacher!) Why don't you put a proper fuse block in it's place? You probably know the safe draw? Just don't sell it when you're done wanting to own it.ReplyDelete
Short answer: I didn't think of it.Delete
Putting anything where Shop-Vac put the fuse sucks, because you have to take the vacuum completely apart to get to it. The answer is to drill holes in the motor cover and run wires to a fuse block, or a resettable breaker on the outside, where I could get to it, just by popping the cover off. Or maybe somewhere that's accessible from the outside.