Blown Transistor Identification .. partial ID only

Discussion in 'General Electronics Chat' started by scot29, May 30, 2014.

  1. scot29

    Thread Starter New Member

    May 30, 2014
    9
    2
    Hi,

    I am trying to repair a control board for my brother's dishwasher, the transistor driving the detergent release solenoid has been blown by failure of the solenoid.
    The solenoid has been replaced with a new unit, tested and confirmed good.

    The transistor has a hole blown in its casing which has obliterated some of the ID numbers & letters. It is a TO-92 package from ST MicroElectronics .. I can still see their logo and the characters 'e3' in a circle.
    Comparing it to similar units on the board I can tell that before the blow out there were 2 rows of 4 characters ..Only the right hand characters remain ..

    _ _ ? 1 ? = partial character may be 8 or S
    _ _ ? S ? = partial character may be 6 or G

    The batch number (?) is also visible lower right and is 849

    A bit of a puzzle for sure .. I hope some one here can help identify the component and save my brother the £100 a new programmed control board would cost..
     
  2. alfacliff

    Well-Known Member

    Dec 13, 2013
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    are there other solenoid driver circuits on the board? they might have the same transistor.
     
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  3. scot29

    Thread Starter New Member

    May 30, 2014
    9
    2
    There are other drivers on the board for the water valves etc ..
    Unfortunately these all use a different model of transistor ..
    The blown one is unique ..
     
  4. wayneh

    Expert

    Sep 9, 2010
    12,103
    3,036
    You may be stuck specifying the part yourself based on the specs of the solenoid. Stick with the same package so that it fits easily, and then shop for the current voltage specs.

    If you can tell whether it's a BJT or a MOSFET, that would help a lot.

    BTW, sometimes you can find pictures of printed circuit boards online (or better yet, a schematic, but those are rare). Maybe you can read the part number in one of those.
     
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  5. Lestraveled

    Well-Known Member

    May 19, 2014
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    Is the solenoid AC or DC? If it is DC then the part is a bjt or Mosfet. If it is AC then the part is probably a SCR or Triac.

    Perhaps a good clear photo might help. A photo with a light shining through the board, to show the traces would be great. You are in detective mode and any clue will help.
     
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  6. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    They never use a TO-92 part when there are critical voltages or currents.

    It's a low power low-ish voltage app, and you can pick a replacement part based on the solenoid coil voltage and current.

    It's likely to be a 12v 250mA coil or something like that (cheap and common) but you should confirm that. Also you can check the DC PSU rail going to the TO-92 part, and the evidence of a diode across the coil terminals neat the TO-92 proves it is a DC solenoid (the majority are).

    A little bit of PCB decoding will do the trick, so please post clear photos of both sides of the PCB so we can check components and tracks.
    :)
     
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  7. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Per post #5, is the coil AC or DC and can you detect the rated voltage of the coil.
    Max.
     
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  8. LETITROLL

    Member

    Oct 9, 2013
    218
    2
    Usually these types of home machines use general purpose PNPs or NPNs , i would try bc849 according to post 1
     
  9. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    BC849 is a very low power (10mA max Ic) transistor, in SMD package.

    A BC337 or BC338 should drive most appliance solenoids (like I said 12v 250mA solenoids are very typical).

    If the OP comes back and does a couple of simple tests we can suggest better. :)
     
  10. scot29

    Thread Starter New Member

    May 30, 2014
    9
    2
    Lots of good advice and info, thanks for that.

    My detective work so far is suggesting AC solenoid, based on 3 points

    1 - The other drivers on board are using a triac .. ST Microelectronics Z0107 in TO-92 package.
    2 - I see no diodes associated with the drive circuits ..
    3 - Our detective work with the partial ID number suggested the nearest match was a part with ID ACS1???S which would make it an AC Switch?

    I will take the board out again this afternoon evening and take a series of photos and post these to the thread by end of today.

    Many thanks to you all so far with your involvement .. :)
     
  11. MaxHeadRoom

    Expert

    Jul 18, 2013
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    If you have determined a triac, then it should not be hard to sub one in, triacs are generally fairly forgiving as to substitution.
    I would not expect a current above an amp, if that for a small AC solenoid.
    Max.
     
  12. scot29

    Thread Starter New Member

    May 30, 2014
    9
    2
    Ok Attached are 8 pics of the board & components.

    I have taken closer look at solenoid and discovered it is stamped as 230/240V AC 50 Hz .. No other ID numbers on it.

    The solenoid is connected to board via CN08 pins 1 & 2.
    Pin 2 I traced to jumper J027.
    J027 via short piece of track to J001.
    J001 traced to Pin 1 of blown component.

    The close up of trackside shows the connector CN08.
     
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  13. scot29

    Thread Starter New Member

    May 30, 2014
    9
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    The other 2 pics ..
    Showing the Control module (Programmable) & the Power supply board.
     
  14. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Small package Triac!
    And 240v 50hz from a machine in Minn?
    At 240 I would not expect much current for that size of solenoid.
    To use the same package, look for a Triac that is high enough voltage rating with the highest current rating, that is if you cannot find the exact replacement.
    Often the cause of burn out is if the solenoid armature sticks and does not shift over completely.
    It looks like it is protected by a MOV across it.
    Max.
     
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  15. absf

    Senior Member

    Dec 29, 2010
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    If the above numbers are

    ACS1
    __6S

    Then it could be ACS108-6SA = AC line switch. See pdf attached.

    But the "6" looks like G on the blown Q008.

    Allen
     
    Last edited: Jun 1, 2014
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  16. scot29

    Thread Starter New Member

    May 30, 2014
    9
    2
    Re Post 14

    240V ac 50Hz solenoid in Minnesota?

    No, my home address is MN but I am currently visiting with my brother in Scotland.

    I am pretty tempted to order and try the ASC108 seems worth a punt.
     
  17. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Expensive service call!
    At least worth a bottle of Glenfiddich.;)
    Max.
     
  18. Lestraveled

    Well-Known Member

    May 19, 2014
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    I agree with absf, the ASC108 looks like a very good match. The functionality on the data sheet is right, the lack of resistors on the board is right. I could not see the circuit due to the white paint. I think you should get a ASC108 and try it.

    Question: Did you go to Scotland to help your brother fix his dishwasher and drink some good Scotch, or did you go to Scotland to drink some good scotch and help your brother fix a dishwasher? A noble quest ether way. Beautiful country.

    Change that part and let us know.

    Mark
     
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  19. scot29

    Thread Starter New Member

    May 30, 2014
    9
    2
    Ordered the ACS108, should arrive tomorrow. Will post result as soon as its fitted.

    For the right whisky I would travel the world, Glenfiddich's not really my thing, I prefer the Islay Malts Bruichladdich & Ardbeg but especially the now defunct Port Ellen.

    My Brother just got lucky I was passing through on way back from work and stopped in to visit for a week or two as we needed to catch up. He is keeping me fed & watered though. :)
     
  20. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Hopefully that is plural, sounds like an idea to keep a couple on hand, I suspect that may be a common problem as it seems to be sized a tad tight? :(
    Max.
     
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