Canon Flash Repair - Page 1
Forum section: electronics / repair

author: M.Zohaib Usman
author_rank: Unknown
timestamp: May 22, 2021, 06:20:35 pm
content: Hey Everyone hope you all are having a fantastic day. So, My brother was using this flash with a wireless trigger and accidentally dropped this canon flash. Now when you turn it on it keeps on making those high voltage charging sounds but never gets ready to flash a shot. I teared it apart, no physical damage inside, all the connectors are good, no broken wires or anything. The supply side is good too, IGBT works fine, transformer is good etc etc...is the light itself broken now? i didnt open it since it was too much of an effort thought id ask u guys before opening it. What could be the possible reason??Thanks in Advance!

author: penfold
author_rank: Frequent Contributor
timestamp: May 22, 2021, 07:15:39 pm
content: I don't know a huge amount specifically about Canon-branded flashes, but from experience of others, the most frequent cause of the HV whine persisting has been bad battery contacts (or bad batteries etc etc). Which could almost be plausible that they could get a little bent during the impact.Now to test my theory... does it use AA batteries or does it have some swanky built-in lithium?EDIT: On second thoughts, you can give the flash tube a visual check for cracks, I'm pretty sure if it were cracked that it would continue to charge the capacitor and say it's read but fail to flash... but I'm not too sure.

author: M.Zohaib Usman
author_rank: Unknown
timestamp: May 22, 2021, 07:23:52 pm
content: Quote from: penfold on May 22, 2021, 07:15:39 pmYes, it uses rechargeable AA batteries. The cell holders are fine i did a continuity test, also it never shows the Ready to Flash LED.

author: penfold
author_rank: Frequent Contributor
timestamp: May 22, 2021, 07:42:38 pm
content: Would it be possible to measure what happens to the battery voltage, preferably at the input to the HV generator, but elsewhere on the PCB would be ok, when switched on? (Obvious safety disclaimer, there's a lot of energy in that capacitor when charged, and don't do anything you're not comfortable with). So one the safety note, it's worth absolutely disproving the battery theory before even thinking of checking in the capacitor is charging at all.

author: M.Zohaib Usman
author_rank: Unknown
timestamp: May 22, 2021, 07:52:50 pm
content: Quote from: penfold on May 22, 2021, 07:42:38 pmNope, cant try it since u have to remove the connectors to open that up. The inside of it is just so complicated, its just annoying. The connecting wires are also soo short i had a hard time connecting them back up. any other ideas? :/

author: DrG
author_rank: Super Contributor
timestamp: May 22, 2021, 08:05:54 pm
content: Quote from: M.Zohaib Usman on May 22, 2021, 07:52:50 pmCould you post the model of the camera and a clear picture of the flash component?It is quite possible that the tube has been damaged. Are we talking about something like this?

author: nightfire
author_rank: Frequent Contributor
timestamp: May 22, 2021, 10:07:59 pm
content: From my photographic experience, this charging sound means that the flash is trying to charge, but when it does not get ready it probably means it cannot detect the capacitors to be charged to a sufficient level to trigger the flash procedure.Which model is the flash in question?Measuring the capacitor voltage whilst charging would be an idea. Caution: can get dangerous when something goes south...(I remember a colleague with whom i photographed some public festivities some years ago, where we did visitors that were partying in the rain- I protected my flash with a plastic bag, he went some time without... Later that evening, he was photographing in a big disco, and being near the dancefloor, his flash finally went "BOOM" - no parts flying around, but EVERYONE in that room (fittting around nearly 1000 people...) turned heads...Another idea might be the holder/contacs of the flash bulb itself, or some circuitry that checks it- Flashbulbs can be damaged also.(In one of my older flashes (Metz 54MZ-4i) the flashbulb was soldered to make safe contact, so that might not apply.)

author: Miti
author_rank: Super Contributor
timestamp: May 23, 2021, 02:42:07 am
content: Few possible suspects here:1. The board or a contact is cracked somewhere, check carefully after the capacitor discharges.2. The transformer itself may be cracked, the core is brittle and could crack from the shock. Try to wiggle it a bit and see if it seems a bit wobbly, even if visually it is ok.3. The transformer again, from the shock, it may slip a bit on the pins and break the secondary wires. The secondary wire is very thin. Let the cap discharge a bit and then measure the voltage. There should be a residual voltage. If it is zero, most likely the secondary circuit is open.