Kill-A-Watt P3 Meter - Disassembly and Repair
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- čas přidán 17. 07. 2024
- I attempt to repair a venerable watt meter that I abused and broke.
It has been pointed out to me in the comments that I should not use an automotive 32V fuse in a 120VAC application, and I agree. In practice automotive fuses can be used for 120VAC fusing since the arc potential of inductive DC loads is so much greater than with AC, however the brief arc flash of interrupting high current AC fault currents could be a fire hazard and I would not recommend it. It is best to use a protection device rated for your application. - Věda a technologie
The conductive strip is often called a "zebra strip" and has been used forever. I am surprised you have not seen it before. When I was a kid in the '80s I used to disassemble calculators and even then, the dawn of the LCD, contact between a PCB and LCD panel was made in this way. I see that there is a Wikipedia article on these, and there it is called an elastomeric connector.
The strip is composed of a kind of flexible rubber or silicone, with alternating conductive and non-conductive elements. On the strips I've seen, these are at a pitch much greater than the conductors that are being mated, as it were. This allows the strip to be just dropped in without alignment, while providing numerous redundant connections per LCD segment. It goes without saying (but I will say it anyway) that this only works because the LCD consumes almost no current, so the relatively high resistance of the conductors is not a problem.
pillsnotbills Thanks for the info!
I've seen plenty of similar designs where the alignment is hyper-critical. In some devices it's nearly impossible to manually align them correctly once separated. Some large LCD TV/computer display screens and some LCD micro-displays screens (like watches) are examples of this. However, in this particular case the contacts seem to be so large this probably is not a problem.
Wow I'm so glad to see you made another video and the repair is about the same problem I have with a p3 that I have. I did the same sort of thing with the same outcome. Mine also does not work anymore but now I'm pretty sure I can fix it or at least have a starting point on how I might get it going again. Really glad to see you made another video. Hope to see more of your repair videos. They are great and myself as many look forward to them. Please keep them coming.
Classic knurlgnar "You might think that's not safe, but I disagree. That's perfectly not safe." Thanks for the laugh.
@Colson Hezekiah How do you have time to watch movie's when all you do is spam YT??
I literally JUST bought one of these and have it open on my desk in front of me right now to see how it works. Serendipitous!
I used my old home electric meter exactly as you described in your video to determine the operating power of various loads.
Good simple & inexpensive fix for your Killawatt meter. I have one of those also & I find it to be a very good device.
You could have simply used a jumper wire with alligator clips on each end to bypass the open thermal fuse--you know, just to test to see if the meter would power up.
Either way, you fixed your problem. Good job & thanks for sharing!
Those thermal fuses are a one-shot deal, they use them as safety over-temp switches for coffee makers and the like, time for a new one!! ECG used to stock them, guess it would be NTE nowadays.
MrLinuxfreak2000 They are pretty standard components anyway. Any electronic supply house will have them. In the day I used them to repair quite a number of hair dryers for people (the Knurlgnar solution would have been unwise...lol). Now we are at the point that a thermal fuse costs almost as much as a new hair dryer. Crazy world.
pillsnotbills And both are probably either made and/or sourced from China!!!
+MrLinuxfreak2000 That change over killed me. I have a great (now out-of-date) cross reference from ECG. Yes I have the digital NTE cross, but it seemed better to physically look up a device & see if I had an equivalent lol.
I have SO MANY old ECG parts...
Thank you for this information--I overloaded 2 of these off of my solar system and now with you help + gadget review below ---saying the fuse is on Ebay(color coded). Keep up all the great work.
Glad to have you back!
Hello, Knurlgar's Hands! Please tell the rest of Knurlgar that I am glad to see a new video from him, and thanks! Maybe ask him to do a video on the inverter/generator that he mentioned in this video, too. :D Ok, cool. Later!
You probably won't forget, but if it was me I'd mark it with a "no fuse" warning.
John Strabismus Good idea!
***** for me that yellow fuse was ok actually. If i were you, i'd use it instead soldering wires unprotected.
Hi !
Thx for showing ... I have no meter but now I will consider buy one ... now I can repair it !
as you have shown why, it is interesting that people use this to not just reading power usage but also monitoring the plug in grid tie inverters that many off grid'ers use to see how much power they are putting back into grid,
best
Yay a new video!! What took so long?
Hi, nice to see you back with another great video. I was wondering why you didn't take the part out of the other p3 you had; or was that thermal fuse also blown. I really like your videos so please keep them coming.
I just fixed my P4460.01 this way, thanks for the troubleshooting and accuracy testing! To save time I just clipped the fuse out and twisted the wires together with pliers. EVEN SAFER than your method! :) I'll update this post if my house burns down.
I've killed 3 of the 4460's and never put bigger than a regular 15A appliance on them! I returned the other two, but fixed this last out of embarrassment to return it a 3rd time. I think they should use breakers in these things, since they're for dumb consumers like me. Sounds like your model can handle more current and wouldn't have blown on me.
I assumed it was startup burst voltage, as both 'killer loads' measured under 15A stable when I hooked them up. Yet they both killed their respective P4460EZ after an hour or so. Doesn't sounds like that'd kill a thermal fuse. Maybe it will blow from either excessive heat (average power) or a spike in current (instant power). First it was a 90's era fridge, then a 'new old tech' glowing wire type box heater. That 2nd one surprised me, since it measured a steady 14A even and seemed too simple a circuit to fluctuate much!
I really like the way you present yourself. I am re learning a lot of these thing's. I went to school for it many moons ago and I find it still interest me a great deal. So thank you. also if you could respond I forgot the color values on resistors and I used to have like a poem or little story to remember but I forgot it .
JOS.... Bad Boys Rip Our Young Girls But Violet Gives Willinge!!!!!
Enjoyed the tour...
Exactly what went out on mine yesterday, and with a few clips and solder its as good as new LOL They evidently blow them if too many watts flow though for a long time. I was flowing around 1000w for a number of minutes. Maybe 30.
Good to know
Thanx for the tutorial. I wish I knew all the kewl stuff that you know.
Or maybe it's a normal thermal fuse. I am not sure what made you think they were resettable
***** Doh! Yes, it's probably not a resettable type. They look exactly the same but cost more so they likely didn't use that type in this application.
the resettable type fuses are typically low power, and not suitable on the AC mains lines
@@FooBar89 This is monitoring the temperature of a physical power lead at the case power port. It's not part of the power circuit that opens when too much current passes through it. But it is non-resettable.
The thermal protect is a one time only device. Once thermally overloaded, it must be replaced. They do come in various trigger temps & amp/volt rating.
Surprised he didn't know that that fuse was a single- shot component.
Man, thanks a million, I just had thrown mine to the bin, then found the video, dissembled mine, measured the fuses, thermal had no continuity so same issue as yours because I also forced mine to the limits. I just cut the thermal fuse, soldered wires and mine's back.
I do not know if there wil be future concerns with it or if it's advisable to force it to I>15A?.
Thanks and God bless.
anyidea on the protocol for those j1 test points? im assuming ttl serial or i2c just havent pulled the scope out.
Edison electric later became a pretty big concern. You might have heard of it... General Electric?
Congrats on your antique find. When I travel I insist on buying you dinner some day.
A quick check of Ebay for "15a thermal fuse" finds 85C and 105C versions for about $1 each. The higher temp ones (140C and up) are about $0.25 each. This size thermal fuse is not resetable. Only the physically bigger ones are PTC material that recovers when cool.
For a few $ more, you could have a 15A manual reset breaker that would just fit in the space available.
I'd pull the thermal fuse from a trashed hair dryer or curling iron and call it good enough.
What brand of DC clamp on Amp meter do you like?
Is the kill-a-watt basically the same as connecting an amp-meter in-line with a circuit, or is the current sensing decoupled from the actual circuit you're measuring like a clamp meter?
I hade one of these connected to a eu2000i and it ran out of fuel. The next time I used it the current was incorrect. I inquired to the manufacturer and wa load present to recalibrates informed that it needed calibration. I forgot the sequence of buttons to enter recalibration but do remember it needs a 125 volt 10 amp precisely. Btw that thermal fuse is non resettable. They are common in automotive blower motor resistors and hairdryers exc.
How could this be changed to work at higher amps like 30A or 50A (still 115v)?
Given the "hack" what is the new highest operational amps?
The thermal fuse is a NON-resettable thermal fuse. It permanently opens up when its rated temperature is exceeded. By its location, it appears to be monitoring the temperature of the main power output port. You generally would not want it to keep cycling ON/OFF/ON/OFF... with an over-temperature condition. Continued cyclic overheating...as the case plastic might not cool sufficiently before the resettable fuse resets...might eventually cause the plastic case to deform and since it's a main power port, could result in some other more significant failure with loss of case integrity.
You are correct. This was an error on my part. Thanks for the comment.
the strip on top of the LCD is called a zebra strip its used in a lot of LCD displays
I have a similar device but my model has a flaw - that large resistor seems to get hot even after a few minutes of measuring of less than 200 watts. It gets so hot that I even can feel that nasty "hot electronics" smell when I look close at the LCD, and one corner of the LCD gets yellowish because of the heat. So, I don't feel safe using it. Do they all have this issue with that resistor getting so smelly hot?
hey bud does the overload sound device still work
how this meter is able to measre the power factor even its not having the CT in it. Does the IC can measure power factor??
Novice with electronic devices. like your vids and intend to learn about troubleshooting boards.
Great video!! Would that same thermal fuse give you wrong output voltage if it's going bad? I have a p3 and it is giving wrong voltage.
I had a P3 showing wrong voltage and it was a failed film capacitor. Given the relatively high cost of a replacement capacitor and reasonable cost of a replacement P3 meter I'd recommend chucking it in the trash and buying a new one unfortunately.
Does anyone have any info on how to calibrate this unit? In particular the voltage.
Is there anyway to make this meter run off a 9v battery and make it isolated it from the ac volts goin thru it?
The old nokia 5110 and 6110 phones had a simular setup pressing the lcd onto the pcb as this kill-a-watt has :)
Was the price for that thermal fuse too high?
What if you left a gap between the leads of the thermal fuse and bridged it with a short piece of that very small solder that you used. Wouldn't that act as a visible link that would melt and open If a large current passed through it. I really enjoy your videos.
Whether the fuse is needed or not, why not just solder a cheap glass fuse in place of the one you removed? I follow your videos and you're obviously very competent with electronics, I'm just curious why you made the decision to just completely bypass it.
Gadget Addict I didn't have an appropriate one on hand, and I didn't want to have to replace another fuse later. I intend to abuse this meter more in the future.
***** I've been missing your videos, I look forward to seeing your meter abuse! Always entertaining and educational :-)
It's not that kind of fuse. It's a THERMAL fuse. It activates (opens, in this case permanently) when something nearby gets too hot...not when too much power runs through it.
Voltage is reading low after lightning strike or some power line transients or something
I did the same thing you did. cut it out put the leads together with a dab of solder. Ordered a new fuse. got 2 for 8 bucks with crimp connections. Now I'm not sure I'll ever put em in. lol
yeah, I never put a fuse back in. Would be a good idea to though!
Thank thermo was out on mine too
Anyone know how to power the LCD with a 9v battery?
I think it was because the fuse is only rated for 15 amps, I believe they are a thermal trip fuse and not a amperage trip fuse.
no magic smoke hahahah, remember me Big Clive, regards
hi there i have watched many of your videos. they are all great. was wondering if you sell the equipment you repair in your videos and if so, where can i get access to them.
Guy in the big green truck I want the "big green truck"
Michael Metzger
yup im sure, even as rough as "greenie" looks theres a lot of people that do. Sorry we go way way back.
I left a question on how to install a heater to the alternator and the inverter hack where you added 2 inverters together #1
Timothy Moulton Questions answered. :)
Is that black mat you're working on an actual anti static mat (ESD Safe Mat) or is it exactly what it looks like, a door mat?
I am what I am and that's all that I am!
Yes, it is a doormat. Anti-static concerns are way overblown. Unless you are in a production setting it is of almost no utility.
Can you do another inverter review on your next video.
Hi there! I learned the hard way that the Watts Up Pro should NEVER be connected to a square wave inverter. BZZZT and a big cloud of white smoke. The company also went under. I would really really like to get in touch with anyone who worked at the firm's engineering. Would hate to see it go to waste.
Did anyone else notice the magic smoke at 13:59?
Lol bottom left!
Yes, but probably just a bit of flux left over.
It looked like dust blowing by, out of focus.
On my Kill-A-Watt the display is very dim. Any idea what I can do. Should I open it up and clean the screen connectors mentioned at 4:40? Anybody else have a very dim display screen? Thanks.
99.9% alcohol
This is what a friend of mine used to refer to as "Southern Engineering." :-) Just a joke. Thanks for the video.
My P3 is out of calibration, it reads about 10% high on volts, all other functions seem normal. This started after checking an old Onan generator that had a no load output of 132 volts. P3 international said to get a new one, not what I wanted to hear.
Craig Nehring I've seen that in these P3's. It's probably most practical to just buy another one but if you're into fixing this sort of thing check the large film capacitor inside it. When that goes bad it no longer reads the proper voltage.
Did you try replacing the cap? Did it help? My unit reads 143VAC on a 118VAC outlet.
hello knurlgnar24 great demonstration I also ruined a kilowatt meter when Istarted a generator with it pluged in the initial start of the generator caused its voltage to surge and it blew the kw meter.did you know the kilo watt meter will not work properly on square wave. the power supply in it could blow out . Keep the Faith John Millard
Good to know
You should have compared the house electric meters power calculation compared to the other 2.
Ok it fixed it, but I don’t recommend fixing it this way. It could be a fire hazard under the correct conditions now that it doesn’t have a thermal fuse. Jump on eBay and buy some thermal fuses for cheap. They are color coded.
The reason it had a thermal fuse was because of what he called the current resistor (shunt with a know resistance made from a specific material just like in most common multimeters) can heat up when over loaded, or even if not overloaded maybe if it was running in a hotter ambient temperature. The thermal fuse is to protect damaging the shunt from melting or acting like a fuse that could also start a fire.
So do yourself a favor, don’t repair this meter this way. Spend a few dollars and get a pack of thermal fuses. They are common on motors like when you put to much in a blender. So if you have a blender that doesn’t work, you could fix it also. They are color coded, and have text on the fuse as well, not every manufacture is nice enough to print the fuse rating on the PCB board.
But that did have enough room for a resettable fuse to me installed, so that would have been another option. Some problems with this would be if the resettable fuse trios it’s for a reason, then it will turn back on, then trip again. When you look at the kilowatt meter you reading won’t be accurate if you measure something for 24 hours because it could have reset a few times. So that’s probably why they didn’t use a resettable fuse to begin with.
FYI: A resettable temperature fuse is usually rectangular, bigger then that one, encased in some plastic and placed against the motor or thing making heat to prevent damage to the thing making heat. Also used not just on motors, but things like linear transformers in DC bench power supplies, some computer power supplies, transformers in bigger soldering irons, and so on.
I have 2 of the p3's that were used on a campers main cord 30 + amps and now when I plug them in the house they read 147 volts. I checked with my multi meter and its normal at 124.7 volts. Is their any hope of repairing the p3 .
try replacing the film cap
+DMAN22yeah OK thanks I'll try that
@@larryhaney6608 Did you replace the cap? Did it help? My unit reads 143V on a 118V outlet....
@@NeverTookTheTime No I never went back to that project I had another p3 put away and have been using it ever sense . ... I u do yours let me know how comes out please .
@@larryhaney6608 Check this out: www.pupman.com/listarchives/2003/May/msg00077.html
My Kill-a-Watt (model: P4400.01) was reading 143.5V in all my outlets. I was able to re-calibrate my meter by plugging it into a power strip, holding down the VOLT button on the meter and then turning on the power strip to get into the "OPEN" state. And then I followed the instructions from pupman.com (above). My meter now reads 110.1V. Good luck and let me know how you make out.
Didn't you or anyone else notice? This device is fused in the NEUTRAL (the wide blade)! WTF!! How the hell did this ever pass UL listing? (Well not exactly UL; it's rated cETLus, which means it's been tested by ETL to both Canadian CSA and UL standards.) When the fuse blows, it will leave any device plugged into it apparently off but actually energized. If that's a lamp with an Edison base socket the full line voltage will be present on the outer thread of the bulb. He did the right thing by bypassing the fuse; having it unfused is better than being fused in the neutral.
Incidentally, this teardown is of the latest version, model P4400.01; I believe the original model P4400 did not have this problem from another CZcams video.
I have one of these that it reports 30vac to high , you ever seen that ?
Mine reports 25VAC too high. Did you ever get an answer from anyone?
But the other kill-a-watt meter that failed didn't it have the same thermal fuse as you needed? :)
Hagis2k It did, but it still works. I just don't trust it until a tweak a solder connection inside. In retrospect I should have also fixed that one in this video...
You can get thermo-fuses out of things like hair dryers, coffee pots, etc. just about anything with a heating element.
Anyways, your the one using the thing so whats another burn in the carpet...
I think they just use a cheap fuse there. I had mine blow the same fuse (and i fixed it the exact same way, lol). It blew when I had around a 1300 watt load on it. Didnt seem hot either.
I just blew mine today, thought it was safe to test a device with 1500 watts. They shouldn't really rate it 15A. 7.5A maybe, because I've seen someone reported not being able to handle even 1000W.
Have you stopped making videos?
What a HACK!........ I love it ;)
Automotive anything would not be suitable for breaking heavy fault currents @ 120V AC, granted i'd probably bypass that fuse too :) but using a plastic ATO fuse rated for breaking 32V DC is just not right.
codemsan That's a good point. There would be a possibility of an arc over with a 32V rated fuse/breaker. I'm not sure that either one is more dangerous than no fuse at all but I should have mentioned that. It's also worth noting that those automotive grade devices are rated for DC which has a much higher arc potential than AC volt for volt, but they still aren't rated or designed for 120VAC.
Indeed, DC is much harder to break, which is why its considered much more dangerous volt for volts as well. try rectifying mains AC with a resistive ballast then short the DC supply (smoothing caps help) and boom, juicy arcs with not more than a couple hundred volts open circuit. The equivalent of this in AC would need around 10x that (MOT supply) :)
I have just found that I have a similar energy monitoring plug. I have found that it overheated when being run from an inverter but it runs cool from normal mains. I have had similar issues driving LED that use a similar capacitor dropper circuit. I thought the issue was due to the sharp rise times of the square wave edges from the inverter causing an over current. Now I’m not sure but would appreciate your comments. czcams.com/video/dD4_7QR1uXo/video.html. PS I think that fuse you replaced looked like a one time use thermal overload- oops just watched again you said that. Thanks Regards Chris
FWIW, the earlier models didn't have the thermal fuse so essentially you've just downgraded it. I concur with other comments that that is not a resetable fuse but does require replacement after overtemperature has occurred.
Hey do have a email address that i can reach you have some questions
Don't use 12/24v fuses in a 120vac application, they are not rated for that voltage and they can ark over catch fire etc.
This is correct. I made that error in this video.
That thermal fuse is not resettable it's a one-shot below
You could have used a small wire. 0.2mm2
Yours is definitely a newer model than mine that failed after all these years. Mine has a big board that holds the plug and socket parts and a smaller board for the display and buttons. It has a small, soldered in, glass fuse. And mine was made in Taiwan, not China. The older ones used a whole lot more parts and did not use the fuse you cut out. How old is mine? It has a 2001 date code on it. :-) czcams.com/video/MeTVCbjFft4/video.html shows the insides of the older version at 9:45.
Interesting! Thanks for the info.
That is NOT a resetable fuse. It is a thermal fuse that is one time use.
It is NOT a resettable fuse. If it blows, you have to replace it.
I am aware that this video is 5 years old, but comment for the 2020 and up viewers.
Just purchase a new set of thermal fuses on banggood or ali express, and you're good 👍
Edit: car fuses are NOT fit for this purpose. They cannot handle the power of a short.
You are correct on all accounts, except that I would not trust fuses from ali express.
@@knurlgnar24 Okay. Not my favourite source either, but considering that your powermeter was most likely built in China, there is less reason to distrust these sources I mentioned. If you can find a better source, like German , I agree that you would be better of.
Cheers and 🤝🇳🇱
Next time you should not run it through over 16.6 amps
Pretty sure a car fuse isn't rated up to 250V and sticking a 20A into a 15A required fuse location 'just because that's all you have is never a good idea.
You're correct. I made that mistake in this video.
The original fuse number is SF96U-1
@knurlgnar24 Pin this!
You can't use low voltage dc blade fuse for high voltage ac!!! You should not recommend this! Also You should twist this wires before soldering.
ac arcs less than even half the volts of dc so yes you can. its not up to code but it is safe
That style of fuse is not resettable. I know them from coffee makers and such.
powerpop23 I agree with you. My mistake.
The thermal fuses are just cheap!
Interesting, and a very bad idea.