Why won’t a Canon Speedlite 155A fire from the hot shoe on a Canon AE-1?
Asked 9/2/2021
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2 answers
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My Canon AE-1 recognizes that a Speedlite 155A is attached: the meter locks to the flash aperture, the flash powers on, and the test button fires it. The camera is set to 1/60s and the aperture is on A/auto. The flash will also fire if I manually short the hot-shoe contacts, but pressing the shutter does not trigger the flash. I’ve cleaned the hot-shoe contacts, and a different flash works through the camera’s sync port. What is the likely cause, and is there anything to check on the 155A itself?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
4y ago
2 Answers
1
I had this exact same problem with a Canon AE-1 + Speedlite 155A—it would power up and flash via the test button but was never triggered by the camera—and solved it yesterday:
By removing the four tiny screws around the hot shoe connector, you can split the case on the Speedlite flash unit. Very quickly, I noticed that, of the several tiny wires that snake into the hot shoe connector, the yellow wire was split/broken. I was able to strip about 1/16" of wire on either end of the break, solder it, and then wrap it with a tiny piece of electrical tape. Once I managed to get the sides of the case back together and everything buttoned up, the flash unit began working correctly again and was automatically triggered by the AE-1.
NOTE: it is quite difficult to get the flash unit back together, once the various components have been bumped around. Can be done, obviously, but takes quite a bit of time and lots of patience to reassemble, especially without damaging any wires or connections in the process.
Originally by user105392. Source · Licensed CC BY-SA 4.0
user105392
4y ago
0
Generated from our catalog & community — verify before relying on it.
If the AE-1 detects the flash and the 155A fires from its test button, but the shutter still won’t trigger it, the likely fault is inside the flash’s hot-shoe connection rather than the camera settings.
From the reported fix, a broken internal wire in the 155A’s hot-shoe assembly can cause exactly this symptom: the camera senses the flash, but the trigger circuit is not completed when the shutter fires. In that case, opening the flash by removing the small screws around the hot-shoe connector revealed a split wire, which was repaired by resoldering it.
So the most likely cause is a damaged wire or connection inside the Speedlite 155A hot-shoe foot. If you’re comfortable with delicate repair work, inspect the wiring in the shoe/foot assembly for breaks. Otherwise, have the flash serviced. Since the AE-1 appears to recognize the flash and another flash setup works, the problem is probably not your shutter speed, aperture setting, or dirty shoe contacts.
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