Welcome guest. Before posting on our computer help forum, you must register. Click here it's easy and free.

Author Topic: Any electronics/circuitry gurus out there?  (Read 2251 times)

0 Members and 1 Guest are viewing this topic.

giardmi09

    Topic Starter


    Beginner

    Thanked: 6
    • Yes
  • Experience: Experienced
  • OS: Windows 7
Any electronics/circuitry gurus out there?
« on: October 03, 2012, 12:04:29 PM »
I have a small 9 inch touch screen monitor I use in the car, I sometimes remove it and use it in the house when I'm trying new things. I accidentally plugged my laptop's 19 volt charging cord into it rather than the monitor's 12 volt cord. It turned on for a few seconds then quickly shut off (also put off a weak burning smell). Now the standby light comes on but it won't turn on when I press the power button. I'm guessing i blew a diode or a capacitor. I would like to fix it myself. Does anyone have any recommendations as to where I should start in order to get this fixed?

Thanks  :)

Salmon Trout



    Genius

    Thanked: 960
    • Yes
  • Computer: Specs
  • Experience: Experienced
  • OS: Other
Re: Any electronics/circuitry gurus out there?
« Reply #1 on: October 03, 2012, 01:24:05 PM »
Digital electronic devices are very very complicated, and it is unlikely to be something as simple as one "diode or capacitor". A monitor is likely to have just one or two inegrated circuits ("chips") and it is quite possible that you have blown them, in which case the thing is effectively dead. The burning smell is a big clue to what probably happened.



Salmon Trout



    Genius

    Thanked: 960
    • Yes
  • Computer: Specs
  • Experience: Experienced
  • OS: Other
Re: Any electronics/circuitry gurus out there?
« Reply #2 on: October 03, 2012, 03:43:11 PM »
inegrated circuits ("chips")

That's "integrated circuits".

giardmi09

    Topic Starter


    Beginner

    Thanked: 6
    • Yes
  • Experience: Experienced
  • OS: Windows 7
Re: Any electronics/circuitry gurus out there?
« Reply #3 on: October 03, 2012, 04:46:46 PM »
I think it is an integrated circuit...I've attached a photo of the damaged part of the PCB. Does that look like an IC to you? Sorry I'm an electronics noob. And is there any reason I can't buy a new one and solder it on there?

Thanks for your response

[year+ old attachment deleted by admin]

DaveLembke



    Sage
  • Inventor of the Magna-Broom 3000 =)
  • Thanked: 619
  • Certifications: List
  • Computer: Specs
  • Experience: Expert
  • OS: Windows 7
Re: Any electronics/circuitry gurus out there?
« Reply #4 on: October 03, 2012, 04:55:36 PM »
Most of these devices are powered thru a voltage regulator. The regulator likely worked until it got too hot and thats why you didnt have instant smoke show. You will probably be looking for a 7805 regulator blown. More info here. http://en.wikipedia.org/wiki/78xx

If your lucky the 7805 blew and opened circuited on you. If you are not lucky it shorted and passed the secondary leg 19VDC cooking all your 7400 series chips etc that can only handle 5 volts +/- 10-20% without failure. The other issue you could be facing is smoked traces. Sometimes these stand out such as ones that are located on top of bottom of board, but traces that are internal that are very thin in width could open when overloaded. Sometimes you can find these when the PCB blisters from the heat and gas of the smoked trace causing internal pressure and gas trying to escape.

Most products are designed to take a quick surge of up to 50% higher than intended, but a constant 19VDC input would have caused the voltage regulator to heat up quickly.

If you can take snap shots of the damage if you are determined to try to get this working I can try to assist you with what to replace and look for etc. My current career is ET for USPS automation controls and prior to that I worked between ET and IT positions for Allen Bradley, Rockwell Automation, Allied Electronics, and GeoKon.

DaveLembke



    Sage
  • Inventor of the Magna-Broom 3000 =)
  • Thanked: 619
  • Certifications: List
  • Computer: Specs
  • Experience: Expert
  • OS: Windows 7
Re: Any electronics/circuitry gurus out there?
« Reply #5 on: October 03, 2012, 05:00:37 PM »
Posted my response then saw you added pic. Trying to see if I can identify that chip...
 Might be a LM317 like shown here ... http://www.mouser.com/ProductDetail/ON-Semiconductor/LM317LBDG/?qs=sGAEpiMZZMtqO%252bWUGLBzeGbm6CAXcw%252b0 BUT LM317 can take up to 40VDC input ... really need schematic on this to properly identify that chip and neighboring surface mount parts. Might be a needle in hay stack to get one. I'd contact the manufacturer of the device and see if they will share one with you.

Chances of bringing it back from the dead are low, but if you like a challenge and want to spend money go for it. I have brought similar stuff back from the dead, but schematics or knowing the exact part numbers are key to success vs guessing!

giardmi09

    Topic Starter


    Beginner

    Thanked: 6
    • Yes
  • Experience: Experienced
  • OS: Windows 7
Re: Any electronics/circuitry gurus out there?
« Reply #6 on: October 03, 2012, 09:33:26 PM »
Thanks for the info DaveLembke,

I wouldn't mind the challenge of attempting to fix it. I have decent soldering skills, and as long as it doesn't cost me too much money it's worth a shot. I'm going to try to contact the manufacturer and find documentation. This may be difficult as it doesn't seem to have any type of make information on it, but I will try to contact someone from the website that i bought it off of. I will report back here with any information I may find.

Thank you again

Ryuk



    Adviser

    Thanked: 3
    • Experience: Beginner
    • OS: Unknown
    Re: Any electronics/circuitry gurus out there?
    « Reply #7 on: October 04, 2012, 10:16:43 AM »
    its cheaper an easier to get a replacement then burning or shocking your self.  Not all boards will let you replace parts.  I broke a capictor on my one server board changeing drives an luckly I was able to put one in with a higher value an still work.  Saying all that I had someone help me that has a degree in doing that. 

    DaveLembke



      Sage
    • Inventor of the Magna-Broom 3000 =)
    • Thanked: 619
    • Certifications: List
    • Computer: Specs
    • Experience: Expert
    • OS: Windows 7
    Re: Any electronics/circuitry gurus out there?
    « Reply #8 on: October 04, 2012, 04:23:28 PM »
    Quote
    its cheaper an easier to get a replacement then burning or shocking your self

    Low Voltage Circuit! If it were a power supply with 120VAC input, then yes, but 12VDC = NO unless you plan on using your tongue...LOL The only high voltage circuit may be the backlight with a ballast circuit, but just dont have it powered and touch circuitry. Within about 5 seconds after its unplugged of 12VDC power the ballast should be drained. If it were a Flash Circuit for a Camera you'd have to worry about a 400VDC CAP storing power, but not with displays which quickly drain.

    Cheaper and Easier to replace... yes if the funds are there to do so and you don't want a project.

    Depending on application of Capacitor, you can use different values and get by. If you know what you are doing (do the math ) and cant find the correct replacement ( odd microfarad value for example and has to be exact almost an impossibility these days with parts so easy to get ) you can connect 2 capacitors together to make the desired value similar to resistors to take 2 and make a different value that is desired for the application. Biggest importance with capacitors are their rated voltages and polarity if electrolytic or tantalum etc. If it calls for a 50VDC Capacitor, dont use a lesser voltage unless you are positive the voltage will never exceed its maximum operating value or POP, Smoke, and Stench! Tantalum capacitors like to burn like magnesium when they fail.

    Lisa_maree



      Apprentice

    • Just because it fits doesn't mean it works.
    • Thanked: 71
      • Yes
    • Experience: Expert
    • OS: Windows XP
    Re: Any electronics/circuitry gurus out there?
    « Reply #9 on: October 06, 2012, 12:08:03 AM »
    Hi

    Thanks for the clear picture. That IC is a switch mode power supply control IC. If you  can get to the other side of that circuit board check the output capacitor for shorts with an ohm meter, if there is a short remove that IC and check again . Those chips are easily tested with a multimeter as all pins are shorted to each other when they fail.
    It is possibly there is an output zener diode that protects against over voltage on the output of that chip that has gone short as well you will need to remove that diode. When the capacitor shows a reading other than a short you could test the monitor by applying the correct voltage to run the electronics either 5v or 3.3v (get the value from the data on one of the chips connected to that supply) to the terminals of the capacitor use a current limited power supply for this and set the current at 500 ma.

    If you can get a model and make I will see if I can locate a circuit for you

    Lisa