what is wrong with the servo?(50$robot)

[mohamed]

now i finally programmed the ATmega8 but i didnt until now modify the servo
but  just wanted to use what will go on when i plug the servos
here is what happened the led turns on once and never turned again
also the servo didnt rotate at first but after i put my finger on the wires of the batteries (i'm using 4.8v and 9v)
the servo begin to rotat but it didnt rotat a full cycle but it makes something like vibration but it dont rotat
but here is the wiered thing when i touch the ground of the servo with the multimeter and touch the signal bus of the servo it start to rotate so what could be the problem
could anyone help me with that....
thanks

[Trumpkin]

check the voltage that your servos are getting. Are you sure you modified you servos correctly? were you testing continuity when you touched the ground and signal bus? your sure it was the signal bus you touched, right? If you touched the - and + of you servos while testing the continuity you should expect it to rotate.....I think.

[bulkhead]

which LED is this that turned on only once?  If you can, use a multimeter to measure the voltage of the battery (unplugged), and THEN plug it in and see how much the voltage drops.  If it drops a lot then you probably have a direct short somewhere.  Next time this happens (LED goes on only once), it's important to try to collect as much information as possible; feel around for any components that have heated up, (maybe not such a good idea, but...) smell for signs of fried electronics, do a quick visual inspection for neighboring leads that may be touching, etc.  Of course the first thing you should do is disconnect power before the damage gets worse.

If it rotated, and then stopped rotating, this could be the signs of an improperly modified servo.  I'm not sure how the modification here is being done, but is it possible that the servo has reached the position that the PWM is indicating? (I've hacked a few servos by sawing off the potentiometer knob, leaving potential for the remaining stub to still be turned by the servo...)  Someone else answer this.

When you did this last test, touching the ground and signal bus with the multimeter, what setting was your multimeter on?  Was your battery connected (ie, was your servo being powered)?  I ask this, because without power, a servo shouldn't be able to move, even with the small current a multimeter can provide for continuity testing (it can light an LED, but not much more than that).

[pomprocker]

One of the first lines of modifiable code in the driver file is

Code: [Select]

LED_off;

[mohamed]

ok now the led dont light up but the servos after modifications they move well but one of them when i close it's box  it stops rotating could that be the lacke of lubrication on the gears coz i was working too much on the servo until the white lubricate is gone (first time to modify servo), or it just something else?

[airman00]

ok now the led dont light up but the servos after modifications they move well but one of them when i close it's box  it stops rotating could that be the lacke of lubrication on the gears coz i was working too much on the servo until the white lubricate is gone (first time to modify servo), or it just something else?

teh gears would still rotate even if there is a little lubrication

my guess is that one of the gears is stuck, you are not giving it the right pulse, or you modified it wrong.

[mohamed]

ok here is the situation when i've done the modfication when i try to rotate the gears by my hand the middle grear dont rotate with the biggest gear the one u attach the horn to it, but when i rotate it with the microcontroller it rotates well but when the box is closed i think the and i screw it it stop as if the pressure resulting from the screws dont let it rotate so what shall i do?

[airman00]

seems like the box somehow is touching one of the gears or maybe the output shaft.. i guess jsut figure it out , its logical i guess

if you really can't do it then post pics , because otherwise I'd be helping you out blindly

[mohamed]

ok thanks airman i'll post pic soon
thanks for ur help

[Admin]

mohamed, I can't understand any of your posts, not even a little . . .

English might not be your first language, so please use windows word first to grammar/spell check what you write.