Can bad soldering in a CD player cause fire?

[Stabby]

Just wondering. I'm not the best at soldering. I even accidentally cut a track on the PCB of my CD player, which I resolved with a small wire.

Could bad soldering someday cause a short-circuit with fire as a result?

[jackand08]

It depends what kind of current and voltage that is passing through the wire at the time of short circuit. For example, if a thin, high gauge wire is used on a mains connection, say, depending on the flammability of the parts around it and how fast the fuse acted it could easily cause a fire. That is what the fuse is there for on the mains side-to break the circuit if there are any nasty short circuits and prevent a fire from starting.

If the short circuit was on a low voltage, low current part of the circuit (such as in the digital and control parts of the CD player), things would probably just fizzle a little until one of the IC's or components went open circuit then you would simply have a CD player that stops working. Some CD players may also have a fuse on the lower voltage side of the transformer which will prevent any more damage being caused by a short (it probably will not stop the short from damaging anything as the IC's and components are so sensitive).

In short, if the repair was done with the right gauge wire (nothing special for low voltage circuits and mains rated cable for high voltage items), the solder stuck properly and the excess wire was trimmed so that it couldn't touch any other parts, then it is unlikely that a fire would be caused. If is was done incorrectly, depending on the voltage and current, you could have a few sparks or fizzles then a bad smell or a dangerous fire hazard. If the repair was initially fine, on a hi-fi CD player (which doesn't get moved much) it is unlikely to deteriorate whereas is the CD player is portable and suffers from vibrations and shocks, the solder could gradually be shaken off and the wire come free.

Sorry for the lecture, but it is worth explaining all the possibilities. If you feel it would help, upload a picture for other forum members to check.