Author Topic: Relay shield damaged? (Read 6082 times)

vicary · « **on:** January 16, 2013, 05:35:07 am »

I have just assembled a relay shield, and try to test it with an 5V adapter before going into codes.

I found the only leads that are connected but with resistance (about 1K), and tried to connect the 5V power between those two leads. But all I got is a short circuit and the adapter's fuse popped.

Don't know if it is normal to this specific relay model, I got some clicking sound when I gently shake it, which I had never experienced with other 5V relays.

I don't want a single one of my DigiSparks to take the risk for this short circuit test...

Could anybody gives me some suggestion to this?

digistump · « **Reply #1 on:** January 16, 2013, 11:07:26 am »

On the bottom of the shield there are two pins sticking through from the relay next to the 3 pin header connector - can you measure the resistance between these two points? It should be around 100 ohm (and fluctuate).

vicary · « **Reply #2 on:** January 16, 2013, 07:41:49 pm »

I measure a range between 54-59 ohms.

I switched to a salvaged computer PSU, but it just think the coil is a short circuit and shuts off.

Sergio · « **Reply #3 on:** January 16, 2013, 08:10:45 pm »

Any chance you soldered the diode backwards?

digistump · « **Reply #4 on:** January 16, 2013, 09:26:33 pm »

Sergio - good point - vicary - is the diode in the right direction? (the photo is showing the correct direction)

also is the transistor in the correct orientation?

vicary · « **Reply #5 on:** January 16, 2013, 09:35:06 pm »

I oriented the strip as the PCB said so, and the flat side of transistor too.

BTW how can I post a photo here?

digistump · « **Reply #6 on:** January 16, 2013, 10:17:35 pm »

click attach a file

vicary · « **Reply #7 on:** January 16, 2013, 10:44:31 pm »

Can't find the attach button, but it seems HTML works here.

just checked the wiki again, nothing wrong with the orientation I guess.

EDIT: Use attachment instead in the new forum.

digistump · « **Reply #8 on:** January 16, 2013, 11:53:22 pm »

looks right - how much of a rattle do you get with the relay? I can hear a very faint click when I shake mine

I see three possibilities
1) Bad relay
2) Bad diode
3) The relay leads got to hot when soldering and melted the coil

vicary · « **Reply #9 on:** January 17, 2013, 12:14:20 am »

The clicking is not too loud, surely not the coil fell off. I was actually suspecting a loosen switch.

1. It is suspectable.
2. With the diode soldered, I measured a forward voltage of 097 in both ways.
3. Quite confident at this, I did two SMD motor shields before this. Sturdy hands and quick work guaranteed.

digistump · « **Reply #10 on:** January 17, 2013, 01:41:47 am »

send me an email at support at digistump dot com and we\'ll get things worked out for you