Kill-A-Watt P3 Meter - Disassembly and Repair 

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.

Classic knurlgnar "You might think that's not safe, but I disagree. That's perfectly not safe." Thanks for the laugh.

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.

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!

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.

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!

Glad to have you back!

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

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.

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 .

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!

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!

You probably won't forget, but if it was me I'd mark it with a "no fuse" warning.

Yay a new video!! What took so long?

Thanx for the tutorial. I wish I knew all the kewl stuff that you know.

Enjoyed the tour...

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.

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.

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.

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.

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.

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.

the strip on top of the LCD is called a zebra strip its used in a lot of LCD displays

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.

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?

Novice with electronic devices. like your vids and intend to learn about troubleshooting boards.

Or maybe it's a normal thermal fuse. I am not sure what made you think they were resettable

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.

The old nokia 5110 and 6110 phones had a simular setup pressing the lcd onto the pcb as this kill-a-watt has :)

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.

anyidea on the protocol for those j1 test points? im assuming ttl serial or i2c just havent pulled the scope out.

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?

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.

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

This is what a friend of mine used to refer to as "Southern Engineering." :-) Just a joke. Thanks for the video.

hey bud does the overload sound device still work

What brand of DC clamp on Amp meter do you like?

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??

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.

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.

Did anyone else notice the magic smoke at 13:59?

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?

Is there anyway to make this meter run off a 9v battery and make it isolated it from the ac volts goin thru it?

I left a question on how to install a heater to the alternator and the inverter hack where you added 2 inverters together #1

Was the price for that thermal fuse too high?

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?

What a HACK!........ I love it ;)

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.

Thank thermo was out on mine too

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.

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.

Voltage is reading low after lightning strike or some power line transients or something

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

Does anyone have any info on how to calibrate this unit? In particular the voltage.

no magic smoke hahahah, remember me Big Clive, regards

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.

Can you do another inverter review on your next video.

But the other kill-a-watt meter that failed didn't it have the same thermal fuse as you needed? :)

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. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-dD4_7QR1uXo.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

You should have compared the house electric meters power calculation compared to the other 2.

I have one of these that it reports 30vac to high , you ever seen that ?

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...

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.

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 .

Anyone know how to power the LCD with a 9v battery?

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.

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 RU-vid video.

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.

Have you stopped making videos?

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.

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.

That thermal fuse is not resettable it's a one-shot below

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 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. :-) ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-MeTVCbjFft4.html shows the insides of the older version at 9:45.

Hey do have a email address that i can reach you have some questions

That is NOT a resetable fuse. It is a thermal fuse that is one time use.

The original fuse number is SF96U-1

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.

Next time you should not run it through over 16.6 amps

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.

That style of fuse is not resettable. I know them from coffee makers and such.

Interesting, and a very bad idea.

The thermal fuses are just cheap!