Can I rule out the momentary switch being defective if I see a pulse?

9 posts / 0 new
Last post
trailhunter
Offline
Last seen: 2 days 17 hours ago
Joined: 12/23/2015 - 17:56
Posts: 792
Location: Mars
Can I rule out the momentary switch being defective if I see a pulse?

I’m trying to narrow down what is broken (momentary switch or driver)

I’m dealing with a light that is using a taskled b3flex driver, the owner said the light stopped working after he crashed his bike.

There is a momentary switch connected to it. When I push the momentary switch, I see 002 amps registered on my power supply and 000 when I switch it off. Is this enough to tell me that there may not be an issue with the switch but moreso the driver itself? I ruled out the LEDs by connecting the leads to the LEDs directly and they work. Any additional troubleshooting steps I may be able to do to rule out the driver being defective?

Here’s a video https://imgur.com/a/b4jV6L6

kennybobby
kennybobby's picture
Offline
Last seen: 8 hours 21 min ago
Joined: 05/10/2017 - 09:13
Posts: 1258
Location: huntspatch, alabama

Looks like a push button switch to me, does it click when pressed.

If it were momentary then it would only be ON while holding it down.

As mentioned in one of your other numerous threads on this same light,
Unsolder the wires to the switch. then measure for continuity across the switch terminals.
If it is momentary then the continuity beeper will sound while the switch is pressed and turn off when released.
If it is a push button switch, then the continuity will sound after it is pressed and continue to sound until pressed again.

This will rule in or out the switch.

Is your power supply scale set for A or mA? If 2 Amps then something is probably shorted and drawing 28 Watts. If 2 mA then it is barely turning ON

Now i used to think that i was cool,
drivin' around on fossil fuel,
until i saw what i was doin',
was drivin' down the road to ruin. --JT

trailhunter
Offline
Last seen: 2 days 17 hours ago
Joined: 12/23/2015 - 17:56
Posts: 792
Location: Mars

kennybobby wrote:
Looks like a push button switch to me, does it click when pressed.

If it were momentary then it would only be ON while holding it down.

As mentioned in one of your other numerous threads on this same light,
Unsolder the wires to the switch. then measure for continuity across the switch terminals.
If it is momentary then the continuity beeper will sound while the switch is pressed and turn off when released.
If it is a push button switch, then the continuity will sound after it is pressed and continue to sound until pressed again.

This will rule in or out the switch.

Is your power supply scale set for A or mA? If 2 Amps then something is probably shorted and drawing 28 Watts. If 2 mA then it is barely turning ON

Hi Kenny, thank you. I managed to find the owner of the company who helped me out. He hasn’t built this light over 7 years. He helped me find the parts he used and fortunately I was able to order one

This is it. It’s a push button momentary. The flashlight owner said all he has to do is click it once and the light stays on. I was under the impression that momentary switches must be held down to keep the leds on but I am sorely wrong in this case? I placed an order and I will continue to follow your troubleshooting steps, just waiting on finer soldering tips to unsolder the wires.

https://www.newark.com/itw-switches/48-1-rb-n-bk-b/switch-pushbutton-sps...

kennybobby
kennybobby's picture
Offline
Last seen: 8 hours 21 min ago
Joined: 05/10/2017 - 09:13
Posts: 1258
Location: huntspatch, alabama

You are correct that a momentary must be held down to keep the circuit closed;

But that flashlight has a driver with a microcontroller chip that merely has to sense that the switch was momentarily pressed and released, and then it will activate to drive the LEDs. And another momentary press/release will either switch modes or turn it Off.

So none of the current thru the LED has to pass thru the switch in this application.

Now i used to think that i was cool,
drivin' around on fossil fuel,
until i saw what i was doin',
was drivin' down the road to ruin. --JT

trailhunter
Offline
Last seen: 2 days 17 hours ago
Joined: 12/23/2015 - 17:56
Posts: 792
Location: Mars

Ah ha! So that would explain it. If this is the case, would it make sense that I’m just seeing 2mah (i think) go through the switch when it’s on and is there a way to try to and bypass the switch to confirm if it’s the switch that is bad or is the driver is bad? Or does your previous troubleshooting post still apply?

Niko
Offline
Last seen: 1 week 3 days ago
Joined: 02/08/2018 - 09:55
Posts: 177
Location: in der lampe

Simple touch two switch pins with screwdriver. If switch problem, light will work. If not working then is driver.

..probable 2mA not 2mAh.

trailhunter
Offline
Last seen: 2 days 17 hours ago
Joined: 12/23/2015 - 17:56
Posts: 792
Location: Mars

Niko wrote:
Simple touch two switch pins with screwdriver. If switch problem, light will work. If not working then is driver.

..probable 2mA not 2mAh.

So I think what you are saying is to short the button at the buttons terminals while light is powered on. If I short the button, it should act like a switch and signal the light to turn on, bypassing the switch. If it doesn’t turn on, then it’s the switch?

Niko
Offline
Last seen: 1 week 3 days ago
Joined: 02/08/2018 - 09:55
Posts: 177
Location: in der lampe

When you touching pins:
-If not turn on is driver, not switch.
-If turn on is switch.

Quadrupel
Quadrupel's picture
Offline
Last seen: 3 hours 3 min ago
Joined: 12/03/2017 - 10:40
Posts: 1023
Location: Lithuania
Switch looks OK, remove driver, look for bad soldering on ALL components and contacts, cracks, burn out and corrosion signs.