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[on:]

Hey guys,so my problem is that since testing out a new 4-relay module for one of those OEM Arduino clones - namely the Duemilanove 2009 AVR ATmega328p Module Board USB 2.0 Cable Arduino Compatible. I can't get the device to either register on a couple of Windows 7 PC's (where it worked prior to this episode) nor work with an external power adapter(it just flashes out on plugin and the power LED on both the Arduino and a LCD+Keypad shield I've plugged in it are lighting up for a bit then start to dim and flicker).
So my questions are A) whether my Arduino dead or it's recoverable and B)If it is recoverable - how can I resurrect the little bugger?

Current setup:
-the aforementioned Arduino clone
-a DFRobot Arduino LCD KeyPad Shield (SKU: DFR0009) (plugged in ontop of the Arduino)
-a generic 4-relay module
(and not sure if it's relevant)- 4 Thermistor-based thermometers

I suspect that the flickering power LED might be caused by a blown voltage regulator,but I'm stumped why the thing isn't recognized via USB

Edit: I forgot to mention that the thing 'died' when the current program (a simple relay 1 through 4 'ON') ran for its first and only time so far and the screen dimmed quite a bit and after unplugging and replugging the USB cable the thing flat out refused to start

[Reply #1 on:]

Edit: I forgot to mention that the thing 'died' when the current program (a simple relay 1 through 4 'ON') ran for its first and only time so far and the screen dimmed quite a bit and after unplugging and replugging the USB cable the thing flat out refused to start

Sounds like maybe a lot of current went across somewhere.

Did you try unplugging all the stuff and just trying to get the bare board to work?

[Reply #2 on:]

Yes,I stripped everything from the Arduino - luckily,everything's connected to the LCD/Keypad shield. Still,the device flat our refuses to be identified by Windows nor it works with the external adapter. I did stumble upon an entry on instructibles (i think) where someone had similar issues with a Mega board and he traced his to the voltage regulator and confirmed it by measuring whether pins 1 and 2 on it aren't shorted (and in my case they do register as such)

[Reply #3 on:]

Sounds like you have a short circuit somewhere on the board that is causing the Vcc (+5vdc) to be connecting to ground. Both the USB thermofuse (when trying USB) power is probably opening after a short delay and the on board +5vdc voltage regulator (if trying to use external power) is going into overload protection after a short delay. The power led is a very fundamental indicator of a basic 5vdc voltage problem.

 The only think I can tell you to try is to unplug the AVR 328p chip form it's socket and then see if the power LED will stay lite and if the PC can then see a USB connection when plugged into the PC. If that works then you just need to get a replacement 328p (with bootloader), a $5 fix or so.

Good luck;
Lefty

[Reply #4 on:]

Sounds like you have a short circuit somewhere on the board that is causing the Vcc (+5vdc) to be connecting to ground. Both the USB thermofuse (when trying USB) power is probably opening after a short delay and the on board +5vdc voltage regulator (if trying to use external power) is going into overload protection after a short delay. The power led is a very fundamental indicator of a basic 5vdc voltage problem.

 The only think I can tell you to try is to unplug the AVR 328p chip form it's socket and then see if the power LED will stay lite and if the PC can then see a USB connection when plugged into the PC. If that works then you just need to get a replacement 328p (with bootloader), a $5 fix or so.

Good luck;
Lefty

Thought as much,but I wanted to confirm whether that was the issue - so in a nutshell I should replace the regulator first because I'm 99% certain it's gone and if that doesn't clear things to try your recommendation. Either way - even if the bugger is truly gone or salvageable - I'm certain I'll be getting a couple of more of its brethren (or perhaps its Mega cousins),because I really got hooked - my initial project (which is mostly complete) is to use the Arduino to control my home fireplace/home heating system and aside from the hiccup today - it's been perfect for the task at hand.

Edit: As I can't seem to find the standard forum Kudos/Thanks button,I want to say thank you to you and RPCoyle  for the prompt responses and helpful hints

[Reply #5 on:]

Sounds like you have a short circuit somewhere on the board that is causing the Vcc (+5vdc) to be connecting to ground. Both the USB thermofuse (when trying USB) power is probably opening after a short delay and the on board +5vdc voltage regulator (if trying to use external power) is going into overload protection after a short delay. The power led is a very fundamental indicator of a basic 5vdc voltage problem.

 The only think I can tell you to try is to unplug the AVR 328p chip form it's socket and then see if the power LED will stay lite and if the PC can then see a USB connection when plugged into the PC. If that works then you just need to get a replacement 328p (with bootloader), a $5 fix or so.

Good luck;
Lefty

Thought as much,but I wanted to confirm whether that was the issue - so in a nutshell I should replace the regulator first because I'm 99% certain it's gone and if that doesn't clear things to try your recommendation. Either way - even if the bugger is truly gone or salvageable - I'm certain I'll be getting a couple of more of its brethren (or perhaps its Mega cousins),because I really got hooked - my initial project (which is mostly complete) is to use the Arduino to control my home fireplace/home heating system and aside from the hiccup today - it's been perfect for the task at hand.

Edit: As I can't seem to find the standard forum Kudos/Thanks button,I want to say thank you to you and RPCoyle  for the prompt responses and helpful hints

Well I wouldn't replace the voltage regulator as a first effort, regardless of your '99% certainty'. As I said a perfectly good voltage regulator will go into shutdown self protection mode if 'sees' it's output is shorted to ground. Simply unplugging the 328p chip and plugging the board into the USB to see if the PC sees the new USB connection being established (plus see if the power LED stays on) takes just a few seconds and doesn't require heating up the old soldering iron.

Lefty

[Reply #6 on:]

Well I wouldn't replace the voltage regulator as a first effort, regardless of your '99% certainty'. As I said a perfectly good voltage regulator will go into shutdown self protection mode if 'sees' it's output is shorted to ground. Simply unplugging the 328p chip and plugging the board into the USB to see if the PC sees the new USB connection being established (plus see if the power LED stays on) takes just a few seconds and doesn't require heating up the old soldering iron.

Lefty

Well,I removed the chip(I'm surprised how effective your emphasis on 'it takes only a few seconds' was as an argument for checking out the chip first ) and the device is still showing up as 'Unrecognized device' when connected to Windows and it's acting up rather akin to the description given here down to the rapid heating up of the overcurrent protection. As I burned my fingers enough already today,I'll delay checking out the voltage regulator out till tomorrow after work.

[Reply #7 on:]

Ok,so I've removed the voltage regulator,but the device is still not being recognized,so .. I wonder if what burned the regulator didn't bleed through to the USB to Serial converter chip. Any ideas/suggestions? Also - any chance to hookup the Arduino directly to a PC's com port?
Edit: It's almost certainly the interface chip,because with the voltage regulator removed (as per the link I provided),the Arduino successfully started and executed the last program flashed to it

[Reply #8 on:]

Well you most likely have a short circuit somewhere between Vcc and ground. It could be the USB serial converter chip, some cap, or maybe (the horror) more then one component short circuited. There comes a time when you have to decide if the time spent is worth the effort. If it is, then maybe use an ohm meter to read between Vcc and ground and if it shows a very low resistance, just start removing components one by one until the short circuit is removed. Me, I would write the board off as a learning experience and get a new one. 

Lefty

[Reply #9 on:]

Well you most likely have a short circuit somewhere between Vcc and ground. It could be the USB serial converter chip, some cap, or maybe (the horror) more then one component short circuited. There comes a time when you have to decide if the time spent is worth the effort. If it is, then maybe use an ohm meter to read between Vcc and ground and if it shows a very low resistance, just start removing components one by one until the short circuit is removed. Me, I would write the board off as a learning experience and get a new one.  

Lefty

Oh,I assumed it's a lost cause as soon as it went on the fritz and I did order a couple of replacement boards (at 11 bucks apiece with free shipping, no sense in wasting time wondering if I should or shouldn't replace it. The question was how many replacement boards should I grab (I settled for 4) .. With that about to be sorted in 2-3 weeks,I just want to experiment with the thing just for the challenge. In fact,aside from the tip about potential multi-component failure on the board(which I'll check out later this week),I found this useful little serial to ttl converter
and will see if that could be of some use reprogramming the 'unsalvageable' board. Worst case scenario - I'll waste a couple of hours honing my soldering skills and the best case scenario - I manage to reprogram the ATMega328 and use the device as intended.