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I have a reflex canon 77d, in one beautiful day the "ok" button stopped to work suddenly. I bought an electric contacts cleaner, i applied the spray and it returned to work normally but after 2-3 days the problem comes back. What should i do ? why it comes back?

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i applied the spray and it returned to work normally but after 2-3 days the problem comes back.

In order for that stuff to work, you have to get it on the actual contacts. If you didn't open the camera to get to the button, you probably didn't really clean the contacts effectively. I don't know what the button itself looks like, but many small switches like that are enclosed, so even if you did open the camera it might be hard to really clean the contacts.

Some other possibilities are:

  • The cleaning action moved some dirt, allowing the switch to work better, but it's since moved back.
  • There's a deeper problem like corrosion or arcing that has caused the problem to recur.
  • The problem isn't actually the switch, but perhaps a loose connection between the switch and board, or something like that.
  • The cleaning was effective, but caused a new problem such as causing the switch covering to deteriorate.

Your options to fix the problem, ranked from least expensive to most effective:

  • Keep trying to fix it yourself. (This may actually be the most expensive in the long run.)
  • Take it to a local camera shop.
  • Send it to Canon for repair.

There are a bunch of videos online where people take DSLRs apart... if you're thinking of attempting the repair yourself you should watch some of those to get a feel for how the parts are likely to go together, where the screws are, etc. If you can get hold of a repair manual, that will of course help a lot.

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TL;DR: Blindly spraying nondescript contact cleaner into anything you wouldn't disassemble, BAD IDEA.

Electrical contact cleaners are usually designed for contacts that rub against each other in use - eg potentiometer wipers, sliding switches, rotary switches, plugs - you are supposed to exercise the contacts after wetting them with contact cleaner.

A push button makes contact just by pressure, and cannot be exercised well.

Any contact cleaner that would be effective in removing oxide layers just by spraying on and soaking is very likely to a) be supposed to thoroughly have its residue REMOVED from the contacts after use, b) be orders of magnitude too aggressive and corrosive to be suitable for blindly spraying into a fully assembled device where it can creep in uncontrolled, also because it is likely to c) be electrically conductive - in the worst case even the dry residue is or will become conductive at the slightest hint of moisture, not to mention flammable, d) make stuff it is used on smell to high heaven :)


The pushbuttons in modern electronics are SOMETIMES based on replaceable, standardized parts (google "tactile button". Would still require camera disassembly and good soldering skills to replace.), sometimes they are custom membrane switches integrated into circuit boards (might be cleanable with contact cleaner or solvent or even abrasives, but in any case disassembly is required).

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