Phillips screw security bit?

The Kill-A-Watt appears to be a heavily integrated product. You probably won't be able to fix it.

Various dealers often have it on sale. It might be less trouble to wait a week or two.

No fusible link?

Thanks for your reply,

--
David Farber
Los Osos, CA

Hmmm. Just checked the back of the 4460 here and all three screw heads are Philips. It's a few years old, though, so maybe their lawyers got involved or something.

Regardless, I wonder if a "spanner security bit" would work here? It's shaped rather like a regular flat-bladed screwdriver but with a notch in the center. You could probably make one by sizing a small flatblade with one of the other screws and grinding a notch in the center.

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Rich Webb     Norfolk, VA

Yeah, the whole thing is the fusible link.

tm

Nice. (-;

Thanks for you reply (I think)

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David Farber
Los Osos, CA

Well, there is a shunt about 1 mm in diameter in the L1 leg. N goes straight through. There is a small fuse, a 0.47 uF cap, and a 100 ohm 1 watt flame proof resistor supplying power to the active electronics. My unit is several years old and has three phillips screws.

Is yours open from source to load?

tm

I took a very small regular flat-bladed screwdriver and didn't expect much. However it was able to catch hold and remove the screw. The screw is just a regular Phillips head that looks like it suffered some irregularities from trying to be removed with the wrong tool. I guess it doesn't really matter now. Inside, everything looks clean. There is a small 10mm pigtail 200ma fuse which is in tact.

So I reassembled everything, plugged it back in and it worked. Now for the big d'oh moment. I think when I tested the Kill-A-Watt after the blowout, it was before I noticed the circuit breaker had been tripped. Ok, move along, nothing to see here. (-:

Thanks for your reply.

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David Farber
Los Osos, CA

Nothing open. The unit now works. Thanks for taking the trouble to research this. See my post after Rich Webb's to see what happened.

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David Farber
Los Osos, CA

To the best of my knowledge, there's no such thing. All my Kill-a-watt boxes use standard Philips screw heads.

Photo of the guts which may help once you gain entry:

The upper photo is the older 4 button version. The lower photo is the

5 button version. Except for the price tag, the differences are subtle.

The fuse is labeled F1 in the lower left. I had the brass power plug connections develop a broken solder connection, probably from excessive movement of the power plug (i.e. tripping over the cord).

The patent might help if you have to troubleshoot down to the component level:

Some litigatory entertainment value:

--
Jeff Liebermann     jeffl@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann     AE6KS    831-336-2558

Hi Jeff,

I posted a few minutes before your post that there was nothing wrong with the meter. I had tested the meter before I had realized the circuit breaker had tripped. The fact that the burn-marked ground terminal that plugs into the wall did not connect to any of the circuitry in the Kill-A-Watt should have been my first clue. It just passes the ground connection to the device under test.

Thanks for your reply.

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David Farber
Los Osos, CA

"William Sommerwerck" wrote in news:i9i6vm$4dl$ snipped-for-privacy@news.eternal-september.org:

it's still nice to be able to open one up and see what's inside.

--
Jim Yanik
jyanik
at
localnet
dot com

That calls for 30 wacks with a rubber chicken! ;-)

--
Politicians should only get paid if the budget is balanced, and there is
enough left over to pay them.

David-

I had a generator with a bad governor, putting out over 300 Volts. It blew the 200 Ma fuse in my Kill-A-Watt.

I haven't been able to find a 200 Ma fuse. It turns out that a standard

1/4 inch 1/4 Amp fuse with wire leads soldered on, fits in the space available. Its better than no fuse at all!

Your philips screw may have just had a mutilated standard head. But if someone went into it before you, they could have replaced the screw with one with a "Pozi-Drive" head that looks like philips from a distance. The pozi-drive system can apply more torque to the screw than philips.

If you work on Hewlett Packard test equipment, it might be worthwhile finding some pozi-drive bits.

Fred

You didn't mnetion what a Kill-A-Watt P4460 is in your original post. For the benefit of others, I did a search online. It's an electricity power meter to display how much energy you are using.

The maximum power of an appliance plugged should not exceed 1875 VA.

What did you have plugged in and how much power does it require?

The Torx bit with a hole in the centre is commonly found in modern security bit sets. You should be able to find one in your local hardware store/supermarket. Otherwise, you'll find one on Ebay.

M. Joshi

David Farber;2517895 Wrote:

--
M.Joshi

My intuition is that the Kill-A-Watt doesn't have a fusible link. Its sensing circuit is probably designed to handle 20A or so. The circuitry is probably fed from a high-impedance resistive divider, which would not lend itself to "fuse" protection.

Of course! That's always fun. I've been tempted to open mine.

This raises a possibly related problem -- something I call "CMOS lockup". A device starts working oddly, or not at all, and then after it's for a while, it works again. I've seen this on at least four items.

A picture is worth well maybe a dozen words:

The upper is the older 4 button variety. The lower version is 5 button. Also note the fuse in the lower left.

Max current is 15A (1875VA):

--
Jeff Liebermann     jeffl@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann     AE6KS    831-336-2558

Got it. So, in addition to the rule "When all else fails, use a bigger hammer," we should append "or a smaller screwdriver!"

Well, at least you had a good excuse to crack one open and take a look at the works. No day is wasted when one has learned something new (or at least took something new apart).

--
Rich Webb     Norfolk, VA