G10 Flash Problem after Lens Replacement - Ideas?

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Need some advice on my G10. The story is that I have two G10s -  one had a "lens error" and the other just badly scratched. So I replaced both lenses - one sourced from Chicago and one sourced from China. After replacing both, neither flash will fire. Prior to my meddling both cameras worked perfectly.

I tore them down again and reseated every ribbon cable and internal connection. Same result. If I disable the flash with the menu the shutter fires. If it is set to flash (auto or forced) then the shutter will not fire - the focusing light just hunts around waiting for the flash that never comes.

Now if I put an external flash in the hotshoe - the external flash will fire just fine. Just not the internal. I checked the microswitch under the hotshoe and it is responding fine.  Weird.

So thinking both lens replacement units might be faulty I put the original scratched lens back in (which was working just fine ) and same result - no flash again and no shutter on flash setting.

I am sure it is something I must have done during the reassembly because there are two cameras involved - I just can't figure out what it was.

My other thought is that the capacitor discharged when I disassembled and now it will not re-acquire enough juice to fire.

Any ideas from the Forum? Thanks much.

[John_]

Hi Marc and your welcome. There may be one more stage before the flash fires that is preventing or like you said the bulb is shot.

The flash is triggered at the same time the shutter either opens, first curtain or closes, second curtain. Have you tried setting that to second curtain, first curtain is default. But the external flash works so most likely not that.

Image stabilization signal also has an input but again the ext flash works but try turning that off and see.

Maybe you can try and check the voltage right at the terminals to the flash but be careful you dont get bitten. See if the voltage releases at those 2 terminlas when the flash should fire.

Maybe you can check continuity throught the bulb too.  

Of course now that I think more about what you said, the hot shoe works with external flash I think that isolates it even further to where the trigger signal is sent to the internal flash to fire. Could it be the flash selection signal itself? Have you tried it on Auto as well as On since Off works.

As far as it being a calibration setting Im thinking, that if the shutter is releasing then the flash should go off too and the exteranal flash fires so maybe its not a cal problem. I would think for the shutter to release the system is happy, focus, Image stabilization, etc. The calibration fo the flash is fairly simple, besides needing a specific shade of gray pattern, 18%, is like one step. But I do not have the software.

Only the 1 fuse, F401 is for the flash the other is the one for the battery voltage, F402 and those are good.

I am nutty as you are when it comes to these challenges and sometimes Im successful and sometimes not lol.

I have the service manual for that G10 if you want I will send it if Canon does not block your email address I do not mind.

Let me see what else what you find

John