Repair guides and support for the Canon Speedlite 430EX II external flash assembly.

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My flash 430 exii don't switch on!


I m french, (so sorry for my poor english) and I have a problem with my flash ex 430 exII.

it don't switch on !

All was good a week end,(I have used the flash normaly), but 2 week later , the flash don't switch on.

Never fall. I don't understand.

I have check and change battery but it's always no good.

Do you think that may be the fuse ? If yes, could you please help me to change it ?

Do you have another idea about this problem ? In advance thank you so much for helps and reply .

Answer this question I have this problem too

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5 Answers

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Hi mani,

are the batteries put in the right way (right orientation)? See here on p. 31 of the manual/trouble shooting section.


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Thank you for your reply Steffen.

Yes, battery are in the right way.

(That was the second things that I have checked )

I have also chacked advice from the manual.

Do you have another idea ?

Thank you so much


Hi main, I am sorry that the flash does not work. I did some further research on that issue. It seems that some flash units are just faulty, even when they passed quality control. How old is your flash? Did you buy it used? Is there any chance that you can send it back to your retailer or to Canon?


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You will need a DVM (digital volt meter) to check each batteries.

1. 1.5VDC(regular) should be 1.65V fresh

2. 1.2VDC (NiCd or NiMh) should be 1.29 -1.34V fresh

Minimum using 4AA is 4.47VDC

Maximum voltage is 8VDC

Using external battery like the ATG Elite Gold Battery Pack or Quantum Turbo is 330V. Can't use on 430EX's.

Anyone one of the batteries fail, you can't turn on the flash.

If you can open the flash, check the On/Off Switch using the DVM in Ohm's Scale.

The above information was provided to me by ATG.



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sorry for my english i'm italian .

my flash doesn't switch on because the battery doesn't touch properly the contacs if you try to move the cover of the battery you may see the flash switch on even for a wile but then you realize that's the problem ,

the contacs ! i'm very sad for that because the problem is still there . i try to pull the contacts inside and i fix it but just for a week.

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Check by open the battery door.

Clean the Battery Door's Metal Contact Leads with a Pen Ink Eraser or a Emery Sandpaper.

Then look inside of the Battery Chamber Assy, you will see Four Metal Contacts. Use a flashlight to shine and you will be able to see. Clean those Contacts.

If the Metal Contacts, from the door, are deformed, just pry them out a little.

Unless, you are talking about the On/Off Switch. Meaning you are able to remove the flash.

If that is the case, then you have to use the DVM to check in Ohm Scales.

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the power switch and all other buttons can very easy be exposed to water damage, just one drop or a little sweat can go under and cause corrosion and power or other functions to fail, open and cleaning will fix it and keep it dry after.

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mani will be eternally grateful.
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