Blown Fuses

Hi:

Just sent my Canon 10d, (I really like it), to Canon for what probably is a blown fuse, (camera did not power up). Canon sent me an estimate for $180.00, which includes labor and parts.

Here's my point: This kind of thing seems to happen very frequently to the best and worse of digital cameras. Just look on eBay and do a search on "digital camera as is". In more than half of the listings you'll find that the camera doesn't power up. Such being the case, why don't the manufacturers place the fuse in a compartment that's easily accessible, e.g. like on stereo equipment etc. ? Am I wrong in my thinking?

Regards,

jayemmar

No, they don't. I don't even know if there is a fuse to be honest. I think there is an expectation that the battery can only supply a limited amount of current to begin with.

Since there is a computer in them, there are many different failure point that can cause the internal computer not to start up (cpu, ram, firmware).

I'm with Don - I can't imagine why a camera manufacturer would bother with a fuse in a device which draws power from a battery. I've actually disassembled a Sony DSC-P1 camera (after it died) and there's nothing resembling a fuse inside it.

As far as I know fuses are used protect a system from power surges.

Don't forget- A fuse is a designed failure point. It's not there to annoy you, it is there to help you.

If something goes wrong, the fuse blows to prevent further damage to other components. If your problem truly was a simple blown fuse, you should be happy - your repair bill might have been much higher if your camera didn't have a fuse. You mentioned that fuses are easy to change in stereo equipment - that's because there are so many ways a user can hook up a speaker wrong (shorting wires, etc), that it is a common problem. Cameras are closed systems, so this sort of problem is not an expected case.

So if it truly was a blown fuse, what might have caused it to blow?

As another poster mentioned before, a power surge could have. Adding/removing a secondary battery could do this, and connecting or disconnecting an accessory battery pack or the AC adapter could as well.

A sudden fluctuation in the power load could have done it. (Flash firing, lens moving, etc)

A new battery pack could (today's rechargeables are MUCH more powerful than those of a few years ago, and substantially more powerful than Alkalines)

A new battery TYPE could. The new "hybrid" NIMH rechargables have different voltage/current characteristics under different loads than other battery types.

Lastly, there's the case where some component in your camera truly failed. In this case, the fuse does its designed job, burning out so that the rest of your camera suffers the minimal amount of damage.

When you got your repair quote, did they tell you anything more than how much it will cost to fix? Any more info about the problem?

• David

The battery will supply all the power it can!!! Why is there a warning about shorting the terminals??? A violent event will occur - take my word for it.

It would be more likely that any fuse-like protection - be it i the camera or the battery would be a resetting type. It will reset by itself (and trip again if the fault is still present).

Your probably right, but I am skeptical that every camera design is going to put money into this.

Chances are good that there isn't a fuse in the camera. Typically a small capacitor is used to ensure that the power is even going to the circuit on battery powered devices. Replacing one generally involves desoldering the old one and soldering in a new one. Combined with bench time to diagnose the circuit card $180 sounds reasonable.

--
My gallery is at http://www.thebursiks.info/gallery

Scott

If a fuse blows that means something else in the system is causing it to do so, you still have to find the culprit.

What did and what didn't happen is all speculation. These are high tech boards without fuses and instead uses sensitive capacitors and potentiometers to regulate and protect the equipment.

In this day and age all they have to do is connect a piece of diagnostic equipment and will tell them what's wrong in no time. $180 is reasonable.

tocar said:

As far as I know fuses are used protect a system from power surges.

Click to expand...

Fuses do not protect from power spikes. They react to current, not voltage. Fuses cannot react fast enough for that. The purpose of a fuse is to protect the power supply in the case of a sudden and sustained overload current demand caused by a a shorted component. There is little value to put a fuse into a low voltage battery powered device.

Many of the previous writers have correctly stated that fuses are current activated and are to protect the power supply from overload. They also protect the rest of the circuit from thermal damage when a component fails or a short circuit occurs downstream of the fuse to limit the time a fault current can flow.

Battery powered items need just as much protection as any other - don't let low voltages fool you into thinking they are harmless, take it from one who has had a stailess steel watch strap melted of my wrist when it accidentally shorted across a car battery of "only" 12 volts! Many devices using high capacity Nimh batteries can produce very high short circuit currents.

It is interesting to note, aluminium is made in a smelter pot line where it is kept molten with only about 4.5 volts across each pot (the same voltage as an average camera battery) but at a current of 100-350,000 amps.

It is highly possible a digital camera will have an internal fuse but it may not be easily recognisable as it will most probably be a surface mounted device that does not look like a conventional fuse. In that case, the dismantling of the camera, replacement of the fuse and reassembly, will acount for the service charge as previously mentioned.

Posco said:

Battery powered items need just as much protection as any other -
don't let low voltages fool you into thinking they are harmless,
take it from one who has had a stailess steel watch strap melted of
my wrist when it accidentally shorted across a car battery of
"only" 12 volts! Many devices using high capacity Nimh batteries
can produce very high short circuit currents.

Click to expand...

It's the current that causes the damage, not voltage, per se. You car battery is capable of much more current than your camera battery which as such doesn't pose the same danger. You example is not applicable to the discussion.

--mamallama

Exactly what is a "sensitive" capacitor and how is a pot in a tightly voltage regulated circuit going to protect from excessive current draw?

Rick

tocar said:

If a fuse blows that means something else in the system is causing
it to do so, you still have to find the culprit.

What did and what didn't happen is all speculation. These are high
tech boards without fuses and instead uses sensitive capacitors and
potentiometers to regulate and protect the equipment.

In this day and age all they have to do is connect a piece of
diagnostic equipment and will tell them what's wrong in no time.
$180 is reasonable.

Click to expand...

mamallama said:

It's the current that causes the damage, not voltage, per se. You
car battery is capable of much more current than your camera
battery which as such doesn't pose the same danger. You example is
not applicable to the discussion.

--mamallama

Click to expand...

While a car battery DOES produce more current, camera batteries can be just as dangerous.

Let's use a real-world example. Many cameras take 4 AA batteries. The datasheet for the Energizer 2500mAh AA's can be found at http://data.energizer.com/PDFs/nh15-2500.pdf . From the diagrams, we can see that each one of these guys can put out a whopping 5A at over a volt for almost a half hour. We can safely say from the graph that it can sustain 1 volt @ 5 amps for 20+ minutes.

Assuming our 4 batteries are in series, that gives us 4 volts @ 5 amps for 20 minutes. Since P=IV, we have 20 watts. If you truly believe that this is of no danger, I would love to see you hold onto the end of a 20W soldering iron for 20 minutes.



If that kind of heat is concentrated inside your camera, it's going to get quite hot, potentially to the point of catching fire. In addition, there are some components which just plain are NOT tolerant of certain conditions. Electrolytic capacitors are a good example- with a good blast of current against their normal polarity, many of them puff up and explode.

You can believe whatever you want, but to think that these batteries are harmless is just plain foolish.

• David

WD40 said:

WD40 said:

It's the current that causes the damage, not voltage, per se. You
car battery is capable of much more current than your camera
battery which as such doesn't pose the same danger. You example is
not applicable to the discussion.

--mamallama

Click to expand...

While a car battery DOES produce more current, camera batteries can
be just as dangerous.

Click to expand...

WD40 said:

You can believe whatever you want, but to think that these
batteries are harmless is just plain foolish.

Click to expand...

My statement never said that NiMH batteries are harmless; but to say that they don't pose the same danger as car batteries which can and have burned a finger off if one wearing a ring short a car battery terminal.

And it's not voltage alone that does the harm but current also is necessary, either to produce heat or to stop your heart. Like a common 1.5 volt cell can electrocute you if you stick probes under your dry skin (high resistance barrier) to the moist flesh (very low resistance) and the current path is through your heart. Less than about 100 ma, AC or DC, is needed, IIRC.

Sorry if my statement misled someone.

that supplies different voltages to the cameras systems. I've worked on a number of 10Ds and found them to be prone to this type of fault. The fuses are surface mounted devices on the circuit board and are not designed to be easily replaced. Canon will swap the entire board which costs around $40 but there is a lot of labour involved in replacing it.

All this assumes that this is the fault with your camera. There are several other possibilities including the switches which sense whether the battery or CF doors are open. Personally I'd get a second hand 20D and sell the 10D on eBay. You'll be surprised with how much you get for it.

Roger Salmon said:

that supplies different voltages to the cameras systems. I've
worked on a number of 10Ds and found them to be prone to this type
of fault. The fuses are surface mounted devices on the circuit
board and are not designed to be easily replaced. Canon will swap
the entire board which costs around $40 but there is a lot of
labour involved in replacing it.

Click to expand...

What would be the malfunction that would cause this surface-mounted fuse on the circuit board to blow? And what is the fuse really protecting if, when it blows, you need to swap out the whole board? Seems like the blown fuse itself is enough of a malfunction that you need an easily-replaced fuse to protect it. It's doesn't make sense since the protecting device itself, when it's doing its job, causes a major malfunction.

What am I missing? Or if the fuse were not there, the other malfunction would cause an explosion to do bodily harm to the photographer? That would make sense. You protect something more important than the whole circuit board.

--mamallama

It's a circuit board. It won't blow, it'll just shut down or you'll smell something burning, but it won't blow-up like a miniature bomb... unless you bought a pirated battery as Canon warns.

I suggest you ask Canon. The equivalent board in the 350D has 3 fuses on it.

Roger Salmon said:

I suggest you ask Canon. The equivalent board in the 350D has 3
fuses on it.

Click to expand...

Fusing resistors, I can believe, but pure fuses just for circuit protection make no sense.

--mamallama