Re: For those who believe in electricity

On 4/8/2025 6:44 PM, Frank Krygowski wrote:

On 4/8/2025 6:29 PM, Frank Krygowski wrote:

On 4/8/2025 5:15 PM, Frank Krygowski wrote:

On 4/8/2025 4:00 PM, Zen Cycle wrote:

On 4/8/2025 3:04 PM, Frank Krygowski wrote:

On 4/8/2025 1:40 PM, Zen Cycle wrote:

On 4/8/2025 12:44 PM, Frank Krygowski wrote:

On 4/7/2025 2:58 PM, Zen Cycle wrote:

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Just as a matter of personal interest, can you read the numbers off the 16 pin IC?

It has no numbers or other codes at all! It's solid black with a sort of fine stippled finish.
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Take another look. I can see 4 rows of text but the resolution on the picture isn't good enough to make it out. FWIW, it's the square device in your second picture with 4 solder joints on each side, next to the octagonal device with "220" written on it (that's a 220uH inductor, likely part of a PWM or PS switcher circuit).

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Sorry, Zen, it absolutely has no writing on it. I don't know if I can manage a micro photograph to convince you, but I'm using a high powered loupe in sunlight. It's just a stippled black finish.
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Try again, using this as a reference:
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https://1drv.ms/i/c/5c034a6b86a172e9/ EX6snfFdTeJMl1tfB4xqOUwBXw_4YXVPsbTNjw04Bpgcdw?e=lFRSWg
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4 lines of text. I think I can make out 4x35x on the first line, but that's it.

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Those are reflections. There is no text, no letters, no numbers. I'll try to get a super-closeup photo later, but this is silly.

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Here are two more shots, through a loupe:
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https://live.staticflickr.com/65535/54440036155_e9437c6d58_m.jpg
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https://live.staticflickr.com/65535/54438807352_4bb9fb0d30_m.jpg
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Honest, no text, no letters, no numbers.

Here's a larger version of the better one. I think I clicked wrong before generating that link.
 https://www.flickr.com/photos/16972296@N08/54438807352/in/dateposted- public/
 It does seem odd to have an unlabeled 16 pin device. I can check to see if that's some sort of coating applied over some text.
 ... Nope. Some fine black stuff scraped away, and the surface now looks smoother, but still no visible characters.

Progress, but no definite solution. As I suspected, the problem seems to be the on/off switch, or the circuit it controls.
The switch is the tiny white box toward the bottom of this photo:
https://www.flickr.com/photos/16972296@N08/54435279894/in/dateposted-public/ just below "3R 46 16V" which is probably a capacitor. The black pushbutton sticks out downward in the photo (or backwards, in the mounted headlight) and looks odd in the photo, again because of reflections. That switch is about 4.5mm x 2.5mm x 1.8mm tall. I removed the switch from the circuit board.
I had assumed it was a toggle, but it seems instead to be a momentary switch. It connects to five tiny solder pads. The two big ones, at the "bottom" of the switch in the photo, are just for fastening it to the board. At the "top" face in the photo are three very tiny pads, call them A, B and C.
Playing with a jumper wire ending in two sharp pins, I found that momentary contact from A to C changed the state of the light, on to off to back on, etc. A to B did the same. I had to be careful to touch fairly quickly and not bounce.
At last check, the light is in "on" state. I think if I don't disturb things, it should stay in that state, and I can try reassembling and testing it on the bike. I've got other stuff to work on tonight, so I'll get back to it tomorrow.
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- Frank Krygowski