Author Topic: $50 robot no power?  (Read 6004 times)

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Offline dfoley23Topic starter

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$50 robot no power?
« on: May 22, 2009, 05:58:33 PM »
Ive finished my $50 dollar bot but have some problems i am using the 9v & 4AA battery diagram that another user posted as a schemadic in a multilayerd pdf When i connect my fully charged batteries the sensor bus should read 5v is reads about 0.02 and my Servo bus reads about 0.01. I realized the first time i powered up the circuit board that my voltage regulator got very hot so i unplugged the power. I may have seen a bit of smoke so i checked everything twice then retried the power the voltage regulator didnt get hot but i have no power. I am considering going with the rechargble RC battery that is used in the tutorial. Or exchanging my voltage regulator. I dont really know the problem. i am not getting power not only from the 5v output of the regulator but also from my AA battery pack. I am using a regular 9v, but for the AA's i am using Kodak rechargeble batteries they are rated at 2000 maH is that ok. check out my board and see if it looks ok thankyou.

Offline SmAsH

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Re: $50 robot no power?
« Reply #1 on: May 22, 2009, 07:13:29 PM »
the batteries you have are fine...
im thinking if the regulator is getting very hot there would either be incorrect polarity
or a short somewhere in the power bus/line.
get out your multimeter and measure the resistance of the + and - pins of the power
bus (without the battery plugged in).
and check the polarity of the regulator.
when the shiny side is facing you it goes:
output---gnd---input.
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Offline dfoley23Topic starter

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Re: $50 robot no power?
« Reply #2 on: May 22, 2009, 07:41:43 PM »
Ok so i checked the voltage regulator by testing the input and the ground as + and -, i looked how to measure resistance on a multimeter and it said to use the used Ω. The only setting i could get a steady read on was 2000k Ω, that reading was 1404. Im not sure where else to check you say the power bus? is that the same as the servo bus? Thanks for the help!

Offline SmAsH

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Re: $50 robot no power?
« Reply #3 on: May 22, 2009, 07:46:00 PM »
the "power bus" is the bus that provides power to your electronics...
the two rows of headers furthest from the mcu.
the ones that are bridged with solder.
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Offline dfoley23Topic starter

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Re: $50 robot no power?
« Reply #4 on: May 22, 2009, 07:57:39 PM »
Ok  i checked at the same setting as i did the regulator 2000k Ω is that the right setting? and it started at about 100 but then slowly climbs pass 900 and up , this is the only setting i could get to work the others went up but then when back to just 1 and stopped.

Offline SmAsH

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Re: $50 robot no power?
« Reply #5 on: May 22, 2009, 08:17:59 PM »
can you take a picture of the top of the board for me?
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Offline dfoley23Topic starter

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Re: $50 robot no power?
« Reply #6 on: May 22, 2009, 08:25:53 PM »
Sure here it is 9v connection fell off after multiple examinations



Offline SmAsH

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Re: $50 robot no power?
« Reply #7 on: May 22, 2009, 09:09:48 PM »
the only thing that i cant see connected is the vcc...
do you have a jumper between +5v and vcc?
but it is kinda hard to check a board by just pictures :-\
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Offline HDL_CinC_Dragon

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Re: $50 robot no power?
« Reply #8 on: May 22, 2009, 09:24:04 PM »
If the regulator got extremely hot and now doesnt supply anything from the regulated pin then it is most definitely fried and youre going to need to put in a new one. To double check that the regulator is fried, desolder it from the board and hook up the AA batteries directly to the positive and negative or ground pins and then use your DMM to measure the voltage between the 5v regulated pin and the ground pin. The only explanation for that is there is a short somewhere that is allowing the 5V regulated to go directly to ground. I cant really tell much from the pictures. I run a very high resolution so those pictures are pretty small on my screen. I would get a magnifying glass and check all the solder joints closely. Also make sure no wires melted through eachothers' plastic coatings and are shorting out on each other.

Also, in the top view you have there, it looks like the battery terminals attached to the wires are touching each other. If so that would cause significant irreversible damage to the batteries or worse. Might want to put some sort of insulating shield between the battery hookup terminals
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Offline dfoley23Topic starter

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Re: $50 robot no power?
« Reply #9 on: May 22, 2009, 09:35:30 PM »
what do you mean by vcc, i dont know if i have a jumper to it.
well i bought another voltage regulator to be ready to replace if i need to it seems though that the regulator still supplies power idk. sorry about the pictures i set my camera down resolution to not make pictures so big and now they are too small
If there is a pool of solder that crosser the brass rings on the board will that cause a short because there is a pool on one of the regulator connections.
also here are the pictures links a bit bigger
http://s93.photobucket.com/albums/l72/skank13/05222009074.jpg
http://s93.photobucket.com/albums/l72/skank13/05222009079.jpg
« Last Edit: May 22, 2009, 09:38:57 PM by dfoley23 »

Offline SmAsH

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Re: $50 robot no power?
« Reply #10 on: May 22, 2009, 09:47:04 PM »
well, seeing as we cant find any other cause...
try desoldering the regulator and testing it standalone.
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Offline dfoley23Topic starter

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Re: $50 robot no power?
« Reply #11 on: May 22, 2009, 09:50:17 PM »
Ok will do thanks

Offline dfoley23Topic starter

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Re: $50 robot no power?
« Reply #12 on: May 22, 2009, 10:37:27 PM »
I removed the old regulator and i took out my new regulator and compared the readings of resistance and they were the same about 013 for output ground and 1400 for ground input. If the batteries ever touched negative to positve would that ruin the AA battery pack too or just the batteries because i know the batteries werent touching then i even put some tape around them but they could have touched some other time and something seems wrong with them im going to go with the 6v battery pack. thanks for the help. also is it ok for the IC to stick out a little i pushed it very carefully in and tries to get it as far as possible but it still has a little gap is that ok?

Offline SmAsH

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Re: $50 robot no power?
« Reply #13 on: May 22, 2009, 10:46:32 PM »
the ic can stick out..
just make sure its in far enough in that its touching the socket tabs.
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Offline Webbot

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Re: $50 robot no power?
« Reply #14 on: May 24, 2009, 07:55:03 PM »
Hi  (you used my multi-layered PDF).

I'd remove the processor (take care not to bend the pins).

Check the contacts on the IC socket for short circuits - normally (but not exclusively) adjacent pins by using an Ohm Meter.

Re-attach the battery(s) and power up still without the IC. Check nothing gets hot including the regulator.

If you have a meter then check the correct voltages are present at the correct pins on the IC socket.

Once you are happy- turn off and (after a few minutes) plug in the IC again.

May be too late by now - but check out my tutorial at http://www.societyofrobots.com/member_tutorials/node/190 (Particularly Section 3) for your next build. The circuit may be different but the principals apply.

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Offline hoosier122

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Re: $50 robot no power?
« Reply #15 on: May 24, 2009, 08:37:32 PM »
Sure here it is 9v connection fell off after multiple examinations





Looks like the posts you have the red and black leads connected to could be touching.  Use romex pins if you have extra.

Offline SmAsH

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Re: $50 robot no power?
« Reply #16 on: May 25, 2009, 01:02:14 AM »
someone already stated that...
Quote from: HDL_CinC_Dragon
Also, in the top view you have there, it looks like the battery terminals attached to the wires are touching each other. If so that would cause significant irreversible damage to the batteries or worse. Might want to put some sort of insulating shield between the battery hookup terminals
but yeah, if this problem persists you may want to try using one pack..
i only used one... noise wouldn't really make much of an effect on the $50 robot.
the readings don't have to be precise.
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Offline HDL_CinC_Dragon

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Re: $50 robot no power?
« Reply #17 on: May 25, 2009, 01:23:23 AM »
Grab some wires with alligator clips on both ends (Radioshack has bags of 10 that come in handy. I use em all the time) and hook up your AA battery pack that your using to the unsoldered VReg. Hook positive to positive, ground to ground. Then, using your Digital Multi-Meter(DMM), measure how much voltage your getting from the regulated pin. If youre not getting any voltage your VReg is fried. Make sure youre identifying the pins properly so youre not hooking it up backwards. Only then can you be sure whether or not your VReg is alive.

Also: Test each batteries voltage using your DMM. You should get a reading of at least 1.5 volts from each battery individually. If youre getting less than that then that battery should be replaced with a new one.

Using your DMM to measure resistance in an IC can be very misleading at times.
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Offline dfoley23Topic starter

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Re: $50 robot no power?
« Reply #18 on: May 27, 2009, 01:00:54 PM »
While doing the power tests it really seemed like the batteries were just messed up. But i would test the battery by itself, its a 9v, and it gave me almost 8v, then tested through a 9v connector, the little toy accesory, and it gave me the same but when i test where the headers are soddered i only get about 2v's, so i think the batteries were touching and have been ruined, or maybe just where the header is, is a faulty connection i couldnt sodder the wires on becasue they were strand wire, i like the alligator clip idea, i already ordered some molex connectors so i will try that too. I was using these http://yhst-13185147461285.stores.yahoo.net/elcon175pcwi.html just plain wire connectors i had previously tried the soddering method and it didnt turn out to good. But should i buy a new AA battery pack incase its fried? thanks

Offline HDL_CinC_Dragon

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Re: $50 robot no power?
« Reply #19 on: May 27, 2009, 02:07:24 PM »
If your reading 8v from a 9v battery without a load other than your multimeter and then 2v when you hook it up to the circuit then that is indicative of a dead battery. Before you hook up some new batteries I would just double check again to make sure theres no short circuits. Also, when you do put the new batteries in, try doing it without the Microcontroller first. That way if theres a problem then you dont run the risk of killing your MCU and when you do plug the MCU in and theres suddenly problems that werent there, you know whats causing them.
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Offline dfoley23Topic starter

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Re: $50 robot no power?
« Reply #20 on: June 01, 2009, 08:56:13 PM »
I just got my molex pins in the mail. i bought new batteries and a new AA battery pack made the connections, the power seemed to work now because, the voltage regulator (also new) started to get real hot again. what could cause this  ??? i immediately removed so hopefullly nothing was harmed

Offline Webbot

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Re: $50 robot no power?
« Reply #21 on: June 01, 2009, 09:22:56 PM »
Its getting hot coz its trying to supply too much current.  So you must have a short somewhere on the +5v output from the regulator
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Offline dfoley23Topic starter

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Re: $50 robot no power?
« Reply #22 on: June 01, 2009, 09:27:45 PM »
Im really not seeing anything that is obvious although on my ground line the wires are very close. could it be a short anywhere that could be causing the regulator to heat up. the sodder around the regulator looks good and everything.

Offline HDL_CinC_Dragon

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Re: $50 robot no power?
« Reply #23 on: June 01, 2009, 10:12:25 PM »
If your getting that short circuit even without the MCU in the socket then there has to be a short somewhere at either a solder joint or two wires that are overlapping each other melted during the solder process and exposed two wires to each other. My recommendation is to desolder the entire thing and resolder it. I had to to that like 3 times for different reasons before I finally figured out all the things I had done wrong...
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Offline dfoley23Topic starter

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Re: $50 robot no power?
« Reply #24 on: June 01, 2009, 10:20:57 PM »
I think i found it is where the ground and the wires get to close which then touches the 5v bus from the output. I think that wire has melted and is shorting on 5v bus if you can see in the picture its the little white wire touching the other side of the sensor bus thats ground.

Offline SmAsH

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Re: $50 robot no power?
« Reply #25 on: June 02, 2009, 12:31:33 AM »
maybe, get out ye multimeter ;D
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Offline dfoley23Topic starter

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Re: $50 robot no power?
« Reply #26 on: June 02, 2009, 11:29:01 AM »
Awesome so i corrected the short, and it is getting correct voltages

Offline dfoley23Topic starter

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Re: $50 robot no power?
« Reply #27 on: June 02, 2009, 11:41:23 AM »
well now im getting the device not found error on pony prog i am trying to write the hold_servo hex file to it so i can mod my servos. What would i check with my multimeter to check the voltages of my progamming headers, do you think it could also be a short since the wires are so close together one wire is touching but only to the insulation hmm thanks

Offline dfoley23Topic starter

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Re: $50 robot no power?
« Reply #28 on: June 02, 2009, 12:04:54 PM »
nevermind it works lose ground wire haha yeah 5% done a couple of hours lol

Offline dfoley23Topic starter

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Re: $50 robot no power?
« Reply #29 on: June 03, 2009, 09:35:54 AM »
hmm one of my wheels is moving backwards they are moving in different directions i cant even tell if it reacts to light yet how do i get the servos to move in one direction?

 


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