Help with a circuit board

Discussion in 'General Electronics Chat' started by scott148, Jan 31, 2011.

Thread Status:
Not open for further replies.
  1. scott148

    Thread Starter New Member

    Jan 31, 2011
    9
    0
    I have a circuit board from a 30 amp aga cooker.The repair man told me the circuit board has gone and will cost £500 to replace?Just wanted to know if I could fix it myself with a little help from somebody on here.
    I think maybe some oven cleaner has got on the board,also think the capacitor has gone?just not sure?need some advice?
    I could upload some pictures if that helps.Any help would be great.Thanks
    Also about 6 months ago the relay switches burned out so I replaced them myself and everything was fine until now.
    The capacitor is a nover 470uf 40v(re) -40c+85c the only one i could buy is a panasonic 470uf 50v(re) -40c+85c would that be okay(higher volts)
     
  2. scott148

    Thread Starter New Member

    Jan 31, 2011
    9
    0
    Image removed since it was too big to view.

    hgmjr (moderator)
     
    Last edited by a moderator: Jan 31, 2011
  3. roadey_carl

    Active Member

    Jun 5, 2009
    116
    5
    Pictures pictures pictures!! :D
     
  4. tracecom

    AAC Fanatic!

    Apr 16, 2010
    3,871
    1,394
    Yes, as long as it will physically fit the space.
     
  5. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    Please post well lit and clear (in focus) photos of both sides of the board. Lighting may be best if you go outside to do it, unless you are buried in snow/rain right now.
     
  6. bertus

    Administrator

    Apr 5, 2008
    15,648
    2,348
    Hello,

    I made the picture visible to you.
    It was "blanked-out" for some reason.

    Please use a smaller format next time.

    Bertus
     
  7. scott148

    Thread Starter New Member

    Jan 31, 2011
    9
    0
    Thanks bertus,can I delete the picture and replace it with a smaller one?
     
  8. tracecom

    AAC Fanatic!

    Apr 16, 2010
    3,871
    1,394
    So, it looks like there aren't many electronic parts - maybe a full wave bridge, a ceramic cap, the electrolytic cap, an optoisolator, and a couple of resistors, and a diode. Can you read the markings on any of them?

    I don't see any real sign of oven cleaner damage. What are the symptoms?

    What is that big white thing in the upper left?

    Is the input 240vac? And is that a transformer on the left center?

    Tell us as much as you can about what's written on the components. The picture is quite blurry.
     
  9. scott148

    Thread Starter New Member

    Jan 31, 2011
    9
    0
  10. scott148

    Thread Starter New Member

    Jan 31, 2011
    9
    0
    [​IMG]
    Uploaded with ImageShack.us
    [​IMG]
    Uploaded with ImageShack.us
    When i switch the cooker on the circuit board makes a clicking sound and switches it off almost instantly?The cooker doesn`t work at all.I really don`t wan`t to spend £500 on a new board.The top left hand side (lower picture) is where the oven cleaner has melted away some of the circuit?Does this matter?I think the capacitor has gone.Is there a way to check this?Can somebody please remove the larger picture.Thanks
     
    Last edited: Jan 31, 2011
  11. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    Do you have a DMM (Multimeter)?

    Are you 100% positive the problem is on this board, and not some other one (are there other boards in the unit that control this board?)
     
  12. scott148

    Thread Starter New Member

    Jan 31, 2011
    9
    0
    Yes I do have a multimeter,not sure about dmm?
    There is only one board so i`m quite sure it`s the problem.
     
  13. GetDeviceInfo

    Senior Member

    Jun 7, 2009
    1,571
    230
    If the device has a schematic, scan and post that as well.
     
  14. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    It seems to be a quite simple board. I would guess that the thermostat controls those T-92 relays by means of the little SSR.

    The arcing(?) damage in the upper left corner may indicate that one of the heating elements has gone short. The elements almost certainly have one end to a hot phase, and the relays control current by connecting to the other.

    If you can identify the connections, use the meter on the ohms scale to see if the heating elements are all the same resistance. Then place a lead to earth ground, and see if any of the elements show any conduction to earth. That is a certain indication of a failure in the wiring/element.

    If one has gone short, you will have to replace it, and probably the associated relay. The relay's contacts may be badly burned. If you can solder, you can get a replacement using the manufacturer's data on the case.
     
  15. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    DMM is Digital MultiMeter. On that cap in the center, the light is bouncing off of it, is the top of it perfectly flat, or are the four score marks slightly tilted up to make a small pyramid/bulge?

    Go around the board where the oven cleaner hit and ensure you have continuity along the copper traces and solder joints. e.g. photo of bottom board, make sure there is continuity between all the "solder blobs" on the track that runs around that discolored edge.
     
  16. scott148

    Thread Starter New Member

    Jan 31, 2011
    9
    0
    The cooker is an electric aga that cost £5000.The circuit board sits on top,the elements are in the bottom.An element normally blows once every 3 months although its easy to replace.I have checked all the elements so I know it`s not that.I am quite sure it`s the circuit board,there`s not much else that it can be.
     
  17. scott148

    Thread Starter New Member

    Jan 31, 2011
    9
    0
    DMM of course.,silly me.Yes I have one I have also checked the continuity and it beeps.Looking at the cap yes it`s raised by about a milimeter.Does that mean it`s gone?Is there a way to check this with the dmm?If so could I just solder a new one on myself?Do you need a special solder?Obviously I dont want to further damage the board.
     
    Last edited: Feb 1, 2011
  18. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    If it is bulged on the top, replacing it might fix the issue, or at least reduce the issues. Replace with the same value/voltage, new stock from Panasonic or Nichinon (well, no Chinese/no-name brands).

    No special solder needed, just solder wick or a solder sucker to take the old one out, then add the new one. Should be similar enough in size not to be an issue.
     
  19. scott148

    Thread Starter New Member

    Jan 31, 2011
    9
    0
    Well I soldered on the new capacitor and all seems okay.I cant believe they were going to charge me £500?I am still a little bit worried as the capacitor is not quite the same (50v)?Hope it doesn`t blow up.Thanks for the advice.
    I think i`ve got myself a new hobby.
     
  20. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    Glad to hear the cap fixed it!

    I couldn't quite tell if it was bulging from the photo or not, glad I asked.

    Welcome to your new hobby! Hang around here and you'll learn quite a bit for a lot less than 500 pounds.
     
Loading...
Thread Status:
Not open for further replies.