Pretty blue fire

[Blood-man]

When I was modifying my servo Hitec HS-310, and don't cut the tab completely. So when I turn the power on, gears are stuck and then my 5v regulator make a pretty blue fire. I immediately turn the power off. I seems like all components doesn't hurt, but the 5v resistor become black. Some solder melt and connect + and ground. What the possibilities of total destruction? If possible, how can I fix it?

[SmAsH]

sounds like the motor drew the stall current
the servo should be fine, as long as it wasn't on for too long, the regulator is most likely dead...

[wil.hamilton]

generally if a component becomes black it's fried
have never heard of a case where a component turns black and ISNT fried

[SmAsH]

what about if you paint it! there are quite a few very sturdy ic's out there that can keep going after very rough treatment...
@blood-man, did the regulator get so hot it melted the solder? or was it a bridge you made?

[Joker94]

even if it works get another one just incase some thing is not quite right, it may eventualy blow all  you electronics.

[SmAsH]

well, test it with a multimeter...
but before you replace stuff, fix whats wrong with your circuit... theres no point replacing electronics if they're just gonna fry again!

[Joker94]

sorry, inturperated it the wrong way . just re read it and do what smash said, check it and check it again, And the first point of call, you soldering. If your soldering has created a short fix them. What type of board are you using. Strip board or the type of board featured in the $50 robot tutorial.

Either way get an extremly sharp knife and run it between each row to seperate the solder before you start to resolder when it may not be needed.

And try not to cut corners when you are debugging, it will only cause problems further down the track.

[Blood-man]

my board works good several times, before that. The fire was like 1 or 2 seconds and then after I turn the power off it's gone. There wasn't solder that connect + and ground, so I guess my 5v regulator completely fried.

[SmAsH]

damn, ah well... they're only like 30c anyway...

[Blood-man]

What did you mean?

[wil.hamilton]

he means its not a terrible loss, voltage regulators are very inexpensive

[Blood-man]

Actually it wasn't fire. Probably it was spark, because top of the 5v regulator is OK. I was lazy so I connect main power supply by the pins not the wire. What could happen if + and ground connected for a second or two? How can I check the 5v regulator if it get fried?

[SmAsH]

regulators have always been sturdy to me... ive never fried one
you can check it by desoldering it, connecting battery to vin and gnd and measuring the resulting voltage.
if you get 5V its good, otherwise its stuffed.

[Joker94]

Usind aligator clips would be the easiest way to test the regulator

[SmAsH]

Using alligator clips would be the easiest way to test the regulator

thats how i set up regulation circuits to test small sensors
get some jumper clips from the battery to regulator to multimeter

[Joker94]

quick 'n' easy

[guru]

Also,  before turning a circuit on do a high-impedance test on the power lines. If the impedance of any of the power and ground traces are less than 500 ohm you may have a problem. If near 0 ohm ...then definately. I typically get 1.5Kohm. Of course, if you have a motor *directly* tied to power it will be about 2 ohms or so, and that would be normal...but usually the motor is behind some transistors and so would not be measured in a high impedance test.

Because of decoupling caps in the circuit it is normal for a continuity tester to beep for a sub-second. The decoupling caps initially show as shorts but quickly go high-impedance.

If you have ever opened up devices and seen a "Hi-Pot Test Passed" sticker, this is a sticker from the assembly line tester that tested the power lines for high impedance. A simple but effective test.