I'd expect that larger diode with its cathode connected to the R/C dropper to be a zener, setting the input voltage to the 7805 and transistor/zener regulator. The extra 6V rail is probably there to give more output swing from the opamp which can't reach all the way to its positive supply on the output.
I actually have a different rev of that board, which has a QFP for the processor, but it's either soldered on 'dead-bug' style, or they ordered them with no markings as it doesn't look like they've been etched off. Also, the op-amp on mine is a DIP package, and only one transistor which is a SOT package. May try to post pics later... Incidentally, my KAW has developed the same 'high' voltage reading, and a flickering display... I may try reading the contents of the eeprom too...
I was very surprised when I dismantled a 'UK' equivalent. Similar price bracket, but CT rather than current shunt, proper Cirrus power measurement IC, some sort of masked 8051 core thing. Very nice looking board and layout.
I resolved the 130v+ issue. It turn out to be a capacitor in series with the main prong and the 100 ohm resistor. Capacitor value 0.47uF. Hope this help.
I have the same kill-a-watt meter you do, and it looks a bit different on the inside. My meter has a date code on both boards of 4813, where yours has 4909 and 4309. The insides are very similar but some things have been changed. The other thing is my unit looks to be wave soldered and not hand soldered. I can take some pictures of the boards if you would like to compare the two.
Leakage to ground can be measured while certifying. Leakage between hot and neutral - well it's supposed to have leakage because it consumes power. even though it sounds funny to say that it's certified. Maybe they just want to pass a simple test that they'll do on product import in order to allow it as "safe". Certification doesn't seam an option for this unit :)
They're probably much more concerned about creepage before the fuse, since that could result in a pretty violent current flowing. After the fuse the short circuit current is limited (somewhat, those glass fuses can interrupt at least 30A IIRC). Still almost aggressively irresponsible to put the mains potential on the conductors right next to each other on that presumably not mains-rated ribbon cable. If they put the PE between the two that would half the voltage and increase safety a bit.
I have an Irish version one of these and its also gone out of cal. It reads 213v and the accual voltage is 232. The current is wayyy off. It reads several thousand amps running a pc. I havent found why its doing this though.
That, and you have 240V there. This is designed for 120V from the ground up. I don't think there is any way to convert these to 240 without completely redesigning both PCBs,
the metal buttons is because of the analog reading. With carbon resistance is inconsistent. ......"the load crystals for the capacitor".... I wander, when you paid for it you would guessed what's inside from the price. Why did you bought it then? You understand well what's probably under the cover. And yet you didn't search for better one for 10 times the price of this one. I'm not accusing you, it's a honest question. I'm trying to understand how the electronics market works
It's not that they're cheap that I find remarkable, it's that this is sold retail in america. I bought these at a local Frys, for FSM's sake! If they were e-bay specials out of china, it would be expected. However, they have *supposedly* passed all US safety regulations.
My friend has one of these that actually got hot enough (I assume it was the shunt that got hot) and melted/deformed the case.Surprisingly it still works fine. I have heard a lot of similar stories to your "dead after 3 months" saga. Also,they don't seem to stay in cal long,if they were even cal'd from the factory.(Some of them are wayy out,right out of the box.)
I watched another video that was made in 2015 and there is a fuse right next to that brass bar thing by the plug now. IDK if they upgraded the design a bit?
@13:00 Sure enough, it is an eeprom, however there's nothing intelligible in it, just calibration data from what I gather by reading the one in my KAW (read as a 24Cxx series eeprom, only 56 bytes used).
4.194304 MHz = 1/(2^22), so 22 flip flops or a 22 bit counter give/gives you a pulse every second. That was the most used frequency before they used PLL and 32768 Hz crystals. Agreed on the very bad soldering job there, i think i have never seen worse.
Its nice of them to try and burn their customers' houses down. I wonder what an accurate estimate of how many houses burnt because of these would look like.
+Yosef MacGruber It was a joke. You asked for a solution to dental issues - soylent is a liquid "food" that you could probabably feed people through a feeding-tube, which would hopefully prevent food build up/plaque, since people wouldn't have food in their mouths anymore.
So did you ever figure out why the KAW was reading 18V more than your Fluke?
I'd expect that larger diode with its cathode connected to the R/C dropper to be a zener, setting the input voltage to the 7805 and transistor/zener regulator. The extra 6V rail is probably there to give more output swing from the opamp which can't reach all the way to its positive supply on the output.
It's not, this isn't the only one I've taken apart, and for it to be fake, the Frys's electronics supply chain would have to be compromised.
I actually have a different rev of that board, which has a QFP for the processor, but it's either soldered on 'dead-bug' style, or they ordered them with no markings as it doesn't look like they've been etched off. Also, the op-amp on mine is a DIP package, and only one transistor which is a SOT package. May try to post pics later...
Incidentally, my KAW has developed the same 'high' voltage reading, and a flickering display...
I may try reading the contents of the eeprom too...
Just about any ribbon cable I have seen that is labeled has been labeled for 300 Volts and 60 or 80 degrees C
I was very surprised when I dismantled a 'UK' equivalent. Similar price bracket, but CT rather than current shunt, proper Cirrus power measurement IC, some sort of masked 8051 core thing. Very nice looking board and layout.
I resolved the 130v+ issue. It turn out to be a capacitor in series with the main prong and the 100 ohm resistor. Capacitor value 0.47uF. Hope this help.
That 5th black band on the resistor just means that it's flameproof or something like that.
My country runs on 230VAC. Interested to assemble one myself. Can share schematics or links to where I can learn to build one?
I have the same kill-a-watt meter you do, and it looks a bit different on the inside.
My meter has a date code on both boards of 4813, where yours has 4909 and 4309. The insides are very similar but some things have been changed. The other thing is my unit looks to be wave soldered and not hand soldered. I can take some pictures of the boards if you would like to compare the two.
Cool teardown! Thanks!
I have one of the very early ones (made late 2006), and it is MUCH better made.
Will do a teardown shortly.
An Englishman, an Australian, an American and a Canadian :)
Leakage to ground can be measured while certifying. Leakage between hot and neutral - well it's supposed to have leakage because it consumes power. even though it sounds funny to say that it's certified. Maybe they just want to pass a simple test that they'll do on product import in order to allow it as "safe". Certification doesn't seam an option for this unit :)
They're probably much more concerned about creepage before the fuse, since that could result in a pretty violent current flowing. After the fuse the short circuit current is limited (somewhat, those glass fuses can interrupt at least 30A IIRC).
Still almost aggressively irresponsible to put the mains potential on the conductors right next to each other on that presumably not mains-rated ribbon cable. If they put the PE between the two that would half the voltage and increase safety a bit.
I have an Irish version one of these and its also gone out of cal. It reads 213v and the accual voltage is 232. The current is wayyy off. It reads several thousand amps running a pc. I havent found why its doing this though.
That, and you have 240V there.
This is designed for 120V from the ground up. I don't think there is any way to convert these to 240 without completely redesigning both PCBs,
the metal buttons is because of the analog reading. With carbon resistance is inconsistent. ......"the load crystals for the capacitor".... I wander, when you paid for it you would guessed what's inside from the price. Why did you bought it then? You understand well what's probably under the cover. And yet you didn't search for better one for 10 times the price of this one. I'm not accusing you, it's a honest question. I'm trying to understand how the electronics market works
It's not that they're cheap that I find remarkable, it's that this is sold retail in america. I bought these at a local Frys, for FSM's sake!
If they were e-bay specials out of china, it would be expected. However, they have *supposedly* passed all US safety regulations.
My friend has one of these that actually got hot enough (I assume it was the shunt that got hot) and melted/deformed the case.Surprisingly it still works fine.
I have heard a lot of similar stories to your "dead after 3 months" saga. Also,they don't seem to stay in cal long,if they were even cal'd from the factory.(Some of them are wayy out,right out of the box.)
At least they did not cost out the fuse and replace it with a wire link....... That cap is not an X1 cap, it is a fake......
my kill-a-watt was purchased on ebay and the boards dont look anything like the one in the video
What is the resistance value of the brass current shunt?
gathering you admire the work of these fine units. The one I got doesn't look nearly as bad inside lol.
also, i like the part where you incessantly dave from eev blog the thing to death.
Also I think I'll send them a letter to register my displeasure, even though they won't care in the slightest as they laugh all the way to the bank.
I watched another video that was made in 2015 and there is a fuse right next to that brass bar thing by the plug now. IDK if they upgraded the design a bit?
Hi , its some other revision board. It doesn't have that thermal resettable fuse in this revision.
its fake one. definitely fake
@13:00 Sure enough, it is an eeprom, however there's nothing intelligible in it, just calibration data from what I gather by reading the one in my KAW (read as a 24Cxx series eeprom, only 56 bytes used).
Those cases look good, where did you get them from again? too lazy to rewind...
They're twenty-something buck a pop, IIRC.
I don't know about fire, but mine gets pretty hot alongside the side near where the ribbon cable comes in lol
4.194304 MHz = 1/(2^22), so 22 flip flops or a 22 bit counter give/gives you a pulse every second. That was the most used frequency before they used PLL and 32768 Hz crystals. Agreed on the very bad soldering job there, i think i have never seen worse.
Not the end of the world.. But i wouldn't even want to pay money for that hunk of junk..
Holy shit! Thats pretty dang crusty!
How much do you have to pay for these meters?
Its nice of them to try and burn their customers' houses down. I wonder what an accurate estimate of how many houses burnt because of these would look like.
just cracked mine open, looks like crap hahah but it works :/
Love watching your stuff but would like it much more w/o FF at certain parts.
Bribery.
100 ohm brown black brown..right???
Sweet!
How did that pass any regulations ?
How can I power the LCD with a 9v battery, so that I can use it for lower voltages and see what's going on?
solar
Did you say "Poly Pack"?
Polycase
Anyone want to bet this is a fake/counterfeit kill-a-watt?
Yeah it's just insanely bad all together..
This might be why i have never seen these in the stores here in Sweden.
This guy has a phd
That horrible sound of that pick on the board reminds me of the dentist! EEEECH, EEEECH. Stop!
ScrEEEEECH, ScrEEEEEEEEEEEECH!
Now, please turn your head to the other side..... Thanks.
ScrEEEEEEEEEEEEEEEEEEEEEEEEECH!
+Connor Wolf
It is a new millennium. Why do we not have better alternatives to the pain of the dentist?
+Yosef MacGruber Isn't that what soylent is?
Connor Wolf
Uh, what?
+Yosef MacGruber It was a joke. You asked for a solution to dental issues - soylent is a liquid "food" that you could probabably feed people through a feeding-tube, which would hopefully prevent food build up/plaque, since people wouldn't have food in their mouths anymore.
You may know what you are talking about but you sure do NOT know how to convey the information