Help Required To Identify Electronic Component

Discussion in 'The Projects Forum' started by Clive Long, Aug 29, 2014.

  1. Clive Long

    Thread Starter New Member

    Aug 29, 2014
    12
    0
    Hi,

    I do not have electronics knowledge. I am trying to get a small PCB repaired in a food processor. Some bits of what I would call "resin" have fallen out of the device when I removed the base. There are a few numbers and letters on the resin that might help identify the device.

    RA2JP, 250V and X2

    I have had a poke around the internet for those codes and they might be the numbers from a capacitor but that's really only a guess. I can take out the PCB and see if there is any further information left on the component that shed this resin.

    Am I likely to have any chance of identifying this component, getting a replacement part, and having a stab at a repair?

    Thanks,

    Clive
     
  2. paulktreg

    Distinguished Member

    Jun 2, 2008
    611
    120
    A photograph of the top and bottom side of the board may help?
     
  3. Clive Long

    Thread Starter New Member

    Aug 29, 2014
    12
    0
    Thanks,

    I will have a go at taking out the board tomorrow and photographing. I am assuming placing the picture on a public file share then posting the link will be enough to make the image visible as some forums don't allow posting of pictures inside posts.

    Clive
     
  4. paulktreg

    Distinguished Member

    Jun 2, 2008
    611
    120
    The site has very recently changed to Xenforo so there have been a few minor problems and I'm not sure on what policy is on posting images. I'm sure links will be OK.
     
  5. Nykolas

    Member

    Aug 27, 2013
    87
    31
    The little description the OP offered make me believe it could be a TVS (transient voltage suppressor) or a MOV (metal oxide varistor). Check the GE, Raychem, Citel, Semtech and other websites for product ID. E
     
  6. #12

    Expert

    Nov 30, 2010
    16,278
    6,789
    I'm guessing it's a power line rated dual capacitor, but I can't tell the size from the first post. The RA2JP eludes me.
     
  7. Clive Long

    Thread Starter New Member

    Aug 29, 2014
    12
    0
    Hello,

    Thanks for all your replies.

    I just can't get access to the circuit board. It is in a slot which is blocked by the motor and the motor is somehow fixed to the case but not by a screw. I have attached a couple of pictures but you can't see much. In the closeup picture what you see is the component with a "tear" down the centre. More of the resin cover came out and two pieces when put together spell out 0.1uF (as much as I can work out). I will spend another half an hour fiddling around with the case to see if there is an obvious way to get the board out but I am not hopeful given the hour I spent today. Then it is the landfill for the food processor - which is a shame because I feel probably a £10 soldering iron and a £2 component could fix this.

    https://dl.dropboxusercontent.com/u/32576758/FP base off.jpg

    https://dl.dropboxusercontent.com/u/32576758/Capacitor close up.jpg

    Regards,

    Clive
     
  8. ISB123

    Well-Known Member

    May 21, 2014
    1,239
    527
    White block behind in the shadows looks like a capacitor,brownish thing next to it looks like small PCB mounted transformer similar to ones found in chargers and it looks like its blown.
     
  9. b1u3sf4n09

    Member

    May 23, 2014
    115
    14
    Can you post a picture of the other side of the food processor? There is probably a screw or plastic clip that is holding the motor housing in place that you will have to unfasten. Once removed, you should be able to have an easier time at diagnosing the damage. From your picture, I'm going to agree with ISB123: It looks like a transformer failed. Also, the other 2 components I can see (brown and blue) look like MOVs.
     
  10. Clive Long

    Thread Starter New Member

    Aug 29, 2014
    12
    0
    Ok, I have finally taken it apart. There were two plastic lugs holding the cover to the body that I managed to prize open using an old hacksaw blade (without breaking the lugs !!). When the top cover was off, a final large screw was revealed that was holding the motor to the body. Removed that and some more screws and the motor dropped out and the PCB was slid out.

    The images are:

    https://dl.dropboxusercontent.com/u/32576758/DSCF2135.JPG
    https://dl.dropboxusercontent.com/u/32576758/DSCF2136.JPG
    https://dl.dropboxusercontent.com/u/32576758/DSCF2138.JPG
    https://dl.dropboxusercontent.com/u/32576758/DSCF2139.JPG
    https://dl.dropboxusercontent.com/u/32576758/DSCF2140.JPG
    https://dl.dropboxusercontent.com/u/32576758/DSCF2141.JPG
     
  11. #12

    Expert

    Nov 30, 2010
    16,278
    6,789
    I'm sticking with the power line rated capacitor, except it's not a dual capacitor. It's the same as the one next to it: 0.1 uf rated at 250 volts AC

    Problem is, if a power surge blew this one to pieces, you probably have worse problems. The machine should run without the protective capacitors. Take the remains out and see if the machine will run. If not, you've only just begun to find out what's wrong.
     
  12. Clive Long

    Thread Starter New Member

    Aug 29, 2014
    12
    0
    Yesterday the motor did run smoothly for about 30 seconds. I then released the "pushdown" switch. I then tried running the motor again and the motor turned for less than 1/4 second and stopped. I tried again twice and the motor no longer turned. I was concerned about doing more damage to the circuit by leaving power on as I didnt know the purpose of the blown component. As you have written, whatever caused the component failure might have damaged other components on the board. However, if the failed component can be identified and replaced then I will be able to see if I can get the motor running again. If other components have failed, but not visibly, I don't have the knowledge to test them one by one to determine if any of them should be replaced. So if a replacement capacitor / transformer can be suggested at least I can try that. At this stage just identifying what the component is a source of debate. Are the numbers and letters from the resin fragments any use in identifying what it was?

    Regards
     
  13. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,526
    2,369
    That is a Universal motor and the controller is most likely a simple Triac control, it should be very simple to reverse engineer it based on the very few components there.
    Max.
     
  14. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,526
    2,369
    Looks as though you need a 0.1µf 250v AC RATED capacitor.
    250v minimum, higher even better.
    Max.
     
  15. bertus

    Administrator

    Apr 5, 2008
    15,647
    2,346
    Hello,

    As the capacitor was a X2 rated capacitor, you should replace it with the same type.

    This quote comes from this page of the capsite:
    http://my.execpc.com/~endlr/line-filter

    Bertus
     
    Theagentxero and #12 like this.
  16. Clive Long

    Thread Starter New Member

    Aug 29, 2014
    12
    0
    Hello Bertus,

    Does this look like a suitable replacement capacitor?

    http://www.maplin.co.uk/p/01uf-275v-x2-rfi-metallised-paper-capacitor-n69cn

    Should I replace the other capacitor at the same time?

    Maplin sell a kit with a 40W soldering iron, I can't find my old one. That should be fine for this job?

    Regards,

    Clive Long
     
  17. bertus

    Administrator

    Apr 5, 2008
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  18. Clive Long

    Thread Starter New Member

    Aug 29, 2014
    12
    0
    Hello,

    I bought a replacement capacitor from Maplins and it looked completely different to the original on the board. I checked the part and they are convinced this is the right one. Nowhere on the object is there 0.1 uF !!

    https://dl.dropboxusercontent.com/u/32576758/Replacement capacitor from Maplins.jpg

    So, I took out the old capacitor and tried to fit the new one. They are completely different sizes. However, amazingly, there is a secondary hole on the PCB on the same trace (is that the right word?) that the replacement can be fitted to, so I decided to give it a go. You can see the original hole on the PCB to the right of the new component.

    https://dl.dropboxusercontent.com/u/32576758/Capacitor swapped and broken resistor.jpg

    When I reconnected everything and switched the device on the motor ran beautifully for a few seconds then stopped. Now when I switch on the motor might turn once every 10 attempts and then it turn for less than a quarter of a second and then stops. I thought, " that's it, it's buggered."

    Tonight I had another look at the board and noticed the resistor next to the replaced capacitor was cracked, I hadn't noticed this before. If one looks back at the original photo the crack is there in the resistor, so it didn't happen as a result of the new "capacitor"

    https://dl.dropboxusercontent.com/u/32576758/Original resistor upclose 2134.jpg

    And here is the resistor off the board

    https://dl.dropboxusercontent.com/u/32576758/Broken resistor.jpg

    So, maybe a replacement resistor will fix it.? As far as I can tell the colours are: Green, blue, black, Silver,

    which an online ready-reckoner comes up with 56 Ohms 10%

    Does this look an ok resistor? http://www.maplin.co.uk/p/metal-film-06w-56-ohm-resistor-m56r

    There isn't any other 56Ohm resistor on the Maplins site.

    So I will try that next. Everything else looks ok, but might not be. Some items are so small and with no markings its impossible to see what they are. So if replacing the resistor doesn't fix it, I'm stuck.

    Thanks

    Clive
     
    Last edited: Sep 9, 2014
  19. ISB123

    Well-Known Member

    May 21, 2014
    1,239
    527
    I'm pretty sure you are going to need 1-2W resistor.
     
  20. bertus

    Administrator

    Apr 5, 2008
    15,647
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