Question for the electrical engineers...

[Purple Fencer]

Here's what's going on...

SwordPlay in Burbank has 2 of the Blue Sky Labs boxes. For a whilw now we've been having a problem where the boxes will spontaneously reset.

The other 3 boxes (an old Prieur, a Favero, and a St, George) have not ever had this problem.

The power supplies are tight in the socket.

There are no outside forces I can see (like someone colliding with the pillars the boxes are mounted on)

No other salle who has these boxes has had the same problem

The chips have been replaced.

The boxes are plugged directly into a wall socket

I'm wondering if it's possible that perhaps there's a slight power fluctuation in the building wiring itself that these boxes are sensitive to...while no other electronic system in the salle is affected.

If it IS a power problem, would plugging the boxes into a power strip with a surge protector help?

Thanks

[penguin_2000]

I'm wondering if it's possible that perhaps there's a slight power fluctuation in the building wiring itself that these boxes are sensitive to...while no other electronic system in the salle is affected.

If it IS a power problem, would plugging the boxes into a power strip with a surge protector help?

I'm an electrical engineer, but I don't know that much about household wiring. Chances are that the building's power is NOT causing it to reset. A power strip may help slightly, but if you want to make a really cheap "surge protector", tie the end of the cord into a knot. The wire wrapped around itself acts like a surge protector (read: inductor), actually. This a good idea for your TV and stuff like that as an added safety measure. However, like I said, I doubt the building's power has anything to do with it. Try changing the power supply if there is one. Also, you can what I do when things aren't working: hit it. May be that a wire is loose somewhere... there are 3 possible outcomes to this... a) nothing b) thing fixes itself (usually temporarily) c) thing breaks completely, but at least you can figure out what is broken. Good luck.

[ThatReallyHurt]

Are the boxes sitting on the floor? Is it very dry in the room where they are? It could be something as simple as the odd jolt of static... two fencers shuffling around can generate a fair amount of static...

[ReverseLunge]

Are the boxes sitting on the floor? Is it very dry in the room where they are? It could be something as simple as the odd jolt of static... two fencers shuffling around can generate a fair amount of static...

I don't think that is the case but I'm kind of amazed that you thought of it.

[RITFencing]

Apologies in advance for the technical and math junk.

I'm an electrical engineer, but I don't know that much about household wiring. Chances are that the building's power is NOT causing it to reset. A power strip may help slightly, but if you want to make a really cheap "surge protector", tie the end of the cord into a knot. The wire wrapped around itself acts like a surge protector (read: inductor), actually. This a good idea for your TV and stuff like that as an added safety measure. However, like I said, I doubt the building's power has anything to do with it. Try changing the power supply if there is one. Also, you can what I do when things aren't working: hit it. May be that a wire is loose somewhere... there are 3 possible outcomes to this... a) nothing b) thing fixes itself (usually temporarily) c) thing breaks completely, but at least you can figure out what is broken. Good luck.

I'm a computer engineer, does that count?

Penguin is probably right; I doubt the power in the building is to blame. Here's why:

Power = V * I (voltage times current)

The electricity coming from your wall socket is most likely 120 V. The current coming out depends on what is plugged into it. For the sake of argument, we'll call it 10 amp max. Minute for the wall socket, large for a digital design like a fencing box and actually a reasonably deadly amount.

When that electircity is converted down to a voltage the box wants (most likely 5V,) the current increases by a similar factor so that the overall power is conserved.

V1 * I1 = V2 * I2

V1/V2 = I2/I1

Plugging in what we know, we get

120V/5V = I2/I1

I2 = I1 * 24

I1 = I2 / 24

So the current coming out of the wall socket is 1/24th of what goes into the box. Assuming, again a maximum draw of 10 amps (once again, huge for this kind of design) that gives a draw of 50W. That's nothing.

Sorry about all the techie stuff.

Anyway, it is possible that there is a problem with the power supplies in the boxes themselves. While they get easily enough power in, the output may not be any good. Check to see if they heat up, which may cause malfunctioning. I don't know the blue sky box, but if the supply is external (if there's a big box on the power cable) then try replacing it. Your local radio shack may stock a suitable replacement; just bring the old one in and try to find a new one with the same ratings and connector. The output voltage and current will be listed on the supply.

[yeoldearmourer]

One you lived in Caiforina which has power draw downs The surge protectors should help. I don't know what type of wiring in the building but at one point alum. wiring was used which didn;t carryed the load as well as copper. Then when all else failure hit it

[Larrison]

Here's what's going on...

SwordPlay in Burbank has 2 of the Blue Sky Labs boxes. For a whilw now we've been having a problem where the boxes will spontaneously reset.
[ ... ]
Thanks

Purple -- here's some random things which might help (and no, I'm not an engineer, I just play one at times....)

If it's a spontaneous reset, you've got something going on to either change an input, or trigger something in the chip.

You've done the wiggle test with the power supply? Does that cause any resets? Are any connectors in the box loose or old?

Have you dusted the box out really well? (I mean blow it out really well with one of the air dusters? You might be getting a minor piece of floor debris or dust shorting something). You might also open the box up, turn it over and shake the heck out of it..

Another similar problem is a break in a solder joint that trips when something expands or moves (such as thermal expansion when it heats up in use). Does it reset only after a while? or periodicly? or just at random? Only way to find that is to put your finger (or suitably insulated rod) on parts of the inside of the box and apply pressure or a wiggle. If it resets, then something's fishy there. Then you need to do a very close visual inspection (magnifying glass).

Have you checked for EMI? This is a nasty thing to diagnose. Try moving the boxes to another location in the building and see if the resets continue. Try plugging them into another power line (with a surge protector or UPS between the box and the wall).

[RITFencing]

Purple -- here's some random things which might help (and no, I'm not an engineer, I just play one at times....)

If it's a spontaneous reset, you've got something going on to either change an input, or trigger something in the chip.

You've done the wiggle test with the power supply? Does that cause any resets? Are any connectors in the box loose or old?

Have you dusted the box out really well? (I mean blow it out really well with one of the air dusters? You might be getting a minor piece of floor debris or dust shorting something). You might also open the box up, turn it over and shake the heck out of it..

Another similar problem is a break in a solder joint that trips when something expands or moves (such as thermal expansion when it heats up in use). Does it reset only after a while? or periodicly? or just at random? Only way to find that is to put your finger (or suitably insulated rod) on parts of the inside of the box and apply pressure or a wiggle. If it resets, then something's fishy there. Then you need to do a very close visual inspection (magnifying glass).

Have you checked for EMI? This is a nasty thing to diagnose. Try moving the boxes to another location in the building and see if the resets continue. Try plugging them into another power line (with a surge protector or UPS between the box and the wall).

There are some really good ideas here, but in my proffesional opinion, it's not likely to be interference. This is not a high frequency design, and I doubt the chips are fabbed with a tight process. Also, I doubt that most boxes (or any made primarily to operate off of a wall socket) run off low voltage parts.

It is possible, however, that a sudden current in the part is causing this. If the board inside is poorly made, it may have a high inductance. To get back to math (and calc this time!):

V = L * dI/dt

Volatge across an inductor = the inductance times the change in current with respect to time. If the board has a high inducatnce (L) and there is a sudden draw on the circuit, there could end up being some odd voltages, which could really mess up the thing. If that happens, it's possible that the digital stuff inside will go to an undefined state, and if that happens, the design may have been made to automatically reset.

The voltage drop across an inductor has been a problem for many design engineers in situations like this, but it's just a theory, and probably not the most likely problem.

[penguin_2000]

Guys, it's not a design problem... Purple fencer has already stated that no other club with this box had had this problem. There is something wrong inside the box.

...did you try my hit it into submission technique yet?

[RITFencing]

Guys, it's not a design problem... Purple fencer has already stated that no other club with this box had had this problem. There is something wrong inside the box.

...did you try my hit it into submission technique yet?

Why couldn't it be a design problem with that box or supply?

[mollusk]

I'm not an EE, but I am an engineer.

Anything else ever plugged into the same circuit (wiring shared by the same breaker or fuse)? Things like vacuum cleaners, air conditioners, or a frig can cause pretty large inductive loads when they turn on and temporarily drop the voltage quite a bit. That may be enough to trigger a reboot. A surge protector won't help much, but a UPS would be a solution if that is the problem.

[RITFencing]

I'm not an EE, but I am an engineer.

Anything else ever plugged into the same circuit (wiring shared by the same breaker or fuse)? Things like vacuum cleaners, air conditioners, or a frig can cause pretty large inductive loads when they turn on and temporarily drop the voltage quite a bit. That may be enough to trigger a reboot. A surge protector won't help much, but a UPS would be a solution if that is the problem.

True, but I really doubt a fencing scoring box is a high inductive load, and even if it was, there would be other problems with devices in that circuit. Actually, the problem you discuss is the same as the one in my earlier post, only centered around a different source.

[Purple Fencer]

The boxes are mounted about 7-8 feet off the floor, hanging off a wooden-clad I-beam (ceiling support)....rubber flooring, so I don't know how much static would build up, or if could even reach the box other than through the floor cords.

Weather conditions vary, but I've never found it overly dry or humid.

The box resets are random....there doesn;t seem to be any pattern.

I'm stumped....I'll try the surgr protector, but if that doesn;t work, I'm out of ideas...

[RITFencing]

The boxes are mounted about 7-8 feet off the floor, hanging off a wooden-clad I-beam (ceiling support)....rubber flooring, so I don't know how much static would build up, or if could even reach the box other than through the floor cords.

Weather conditions vary, but I've never found it overly dry or humid.

The box resets are random....there doesn;t seem to be any pattern.

I'm stumped....I'll try the surgr protector, but if that doesn;t work, I'm out of ideas...

Once again, if it's an external power supply, try replacing that. You could also contact the manufacturer.

[Larrison]

The boxes are mounted about 7-8 feet off the floor, hanging off a wooden-clad I-beam (ceiling support)....rubber flooring, so I don't know how much static would build up, or if could even reach the box other than through the floor cords.

Weather conditions vary, but I've never found it overly dry or humid.

The box resets are random....there doesn;t seem to be any pattern.

I'm stumped....I'll try the surgr protector, but if that doesn;t work, I'm out of ideas...

Seriously dude -- if you can, open them up, dust them out and turn them upside down and shake them. Even though they're off the floor, they're gathering dust. Cleaning them won't hurt and might help...

And I'll echo, if you can try to put a UPS on the line instead of a surge protector if you can. That'll help isolate any power problems, whereas a surge protector won't isolate much.

[RITFencing]

Seriously dude -- if you can, open them up, dust them out and turn them upside down and shake them. Even though they're off the floor, they're gathering dust. Cleaning them won't hurt and might help...

And I'll echo, if you can try to put a UPS on the line instead of a surge protector if you can. That'll help isolate any power problems, whereas a surge protector won't isolate much.

I seriously doubt dust is a problem. The main issue is causes is restricted airflow in a system that relies on fans for cooling. Unless these boxes run much hotter than I'd expect, it would be a non issue.

[Purple Fencer]

Maintenance has been done on the boxes before (by the builder), but the problem persists...I have never known them to run hot...if they did, there would be problems at other locations.

[KD5MDK]

I'm not sure where people are saying a surge protector would help. An uninterruptible power supply (UPS) is what you would need to fix problems with the electric supply to the box.

[RITFencing]

I'm not sure where people are saying a surge protector would help. An uninterruptible power supply (UPS) is what you would need to fix problems with the electric supply to the box.

Well, surge protectors have inductors to even out the flow of current, which can take care of the occasional spike or trough. a UPS would work better if it's on the building end. I still think the mostly likely cause is a faulty power supply.

[SJCFU#2]

It is not unheard of for 120vAC coming out of an outlet was so "dirty" that it caused machines to reset, but rare in this country. Do both machines reset at the same time?

Try isolating one machine from the local 120vAC (maybe leave the second machine on its power supply to serve as a control). It's hard to tell from the pictures on Blue Sky's website but it looks like they use an inexpensive 120vAC/12vDC adaptor with a coaxial plug. You could probably rig up a temporaty power supply using a 12-volt lantern battery. If the problem goes away then you know that either the 120vAC/12vDC adaptor is bad or the power going into it is "dirtier" than it can handle, at which point you may consider buying a regulated power supply or a UPS.

If the problem continues even when running on a battery then it's probably internal, at which point you may want to talk to the manufacturer. Possibilites include poor connections at the power socket, a poorly fitted (or missing) heat sink on an internal voltage regulator, or the power switch may be simply be a bit fluky.