Connect with us

Fluke 8846A defective due to overvoltage

Discussion in 'Troubleshooting and Repair' started by mechachris, Nov 2, 2020.

Scroll to continue with content
  1. mechachris

    mechachris

    7
    0
    Nov 2, 2020
    Hello technician,

    I destroyed a Fluke8846A due to incorrect measurements.
    I swapped the primary and secondary side of a 24V transformer and created an overvoltage.
    I had about 900 to 1200 volts at the measuring tips
    I can no longer recognize the SMD imprint on component Q41 in the SOT23 housing.
    Can someone tell me what is written on component Q41?
    I was able to reconstruct everything else.

    Greeting,
    mechachris
     
  2. bertus

    bertus Moderator

    2,028
    761
    Nov 8, 2019
  3. mechachris

    mechachris

    7
    0
    Nov 2, 2020
    Thanks Bertus for the quick answer.
    But unfortunately I can't see the imprint of C41 on the pictures.
     
  4. mechachris

    mechachris

    7
    0
    Nov 2, 2020
    don't know the capacitor C146 either, but there's no print on it either.
    I have to estimate the value
     
  5. bertus

    bertus Moderator

    2,028
    761
    Nov 8, 2019
  6. mechachris

    mechachris

    7
    0
    Nov 2, 2020
    Hello Bertus,
    unfortunately there is no usable picture available.
    I attached a picture for the component search
     

    Attached Files:

  7. bertus

    bertus Moderator

    2,028
    761
    Nov 8, 2019
    Hello,

    Unfortunately, the parts are not carrying any numbers on the picture of the given site:

    fluke8846 part.jpg

    bertus
     
  8. mechachris

    mechachris

    7
    0
    Nov 2, 2020
    Yes exactly!
    On the component Q39 is written PD that means BSS84LT1G = Mosfet transistor P channel.
    There are also 2 letters printed on component Q41. But the photo reflected it.
    You have to moisten the component and illuminate it with a lamp, then you can see the imprint.
     
  9. 73's de Edd

    73's de Edd

    3,121
    1,315
    Aug 21, 2015
    There are also 2 letters printed on component Q41. But the photo reflected it.
    You have to moisten the component and illuminate it with a lamp, then you can see the imprint.

    If that was being the case then, and you WERE able to make them out, why didn't you give those two alfa /numeric symbols to us ?

    Looking at the foil paths, associated with that transistor pair, they seem to be interconnected, akin to Darlington or Sziklai pairing combinations of bipolar circuitry.

    Also, can you determine what Mx pin is involved in receiving that sole related trace from them, that is routed down and over to the right, and then going under the Maxxim 329 octal analog multiplexer 16 pinIC . . . . . . What pin number is it being?
    Thereby confirming if they are being related to an inputting from or an outputting from that MUX chip . . .with my leaning towards their receiving an MUX output.
     
    Last edited: Nov 4, 2020
  10. mechachris

    mechachris

    7
    0
    Nov 2, 2020
    the Q41 burned down on my mainboard.
    There is no print. That's why I don't know which component to use.
    I only know that it is a SOT23 housing.

    I take a photo of my circuit board and draw the connection.

    LG
    mechachris
     
  11. mechachris

    mechachris

    7
    0
    Nov 2, 2020
    I drew the connections.
    Q39 = BSS84L I got that from a picture from the Net
     

    Attached Files:

Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-