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Heat probe for localizing defective devices?

Discussion in 'Electronic Repair' started by JW, Apr 7, 2009.

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  1. JW

    JW Guest


    When doing repair work, I often run into components that fail to work
    properly when they heat up. Usually, I use freeze spray to try to localize
    the problem, but it's getting to the point where components are becoming
    so close together that the freeze spray affects too many devices on the
    PCB. Does anyone know of a off-the-shelf device or piece of test equipment
    that would allow one to heat up individual components on a circuit board?
    something that would have a tip maybe 3 to 5mm. square or so, and have a
    controlled output from 40-100c.

    Thanks for any suggestions.
  2. N_Cook

    N_Cook Guest

    An old soldering iron with 1N4006 and selection of droppers in power line
    and a calibration chart ?
    Also a small accurate localised thermometer probe can be just a 1N4148 and
    diode function of DVM, again calibrated with pan of heated water or
  3. JW

    JW Guest

    Thanks, but I'm looking for something a little more professional that's
    easy to use and reproducible temperature-wise. Something like you describe
    would be temperature dependant on thermal load - a larger device would
    cause the tip to become cooler and a smaller device hotter. I'd like to be
    able to apply a precise temperature to devices from a SOT-23 to a TO-220.
    I spent an hour or two doing some additional searching, and found this:

    I've got a request in for pricing and availability, Hopefully it won't be
    much more than $500 or so...
  4. JW

    JW Guest

    That only measures temperature. I've already got plenty of instruments
    that do that. I'm trying do deliver controlled heat to a device, not just
    measure it.

    Thanks though.
  5. Yukio YANO

    Yukio YANO Guest


    Supposed to see the heat difference between bkgrnd and a human body !
    Go talk to the local fire department ?

    Yukio YANO
  6. Archon

    Archon Guest

    Theres one on Ebay # 380069209309 $557

    A similar function, obviously less controlled, but somewhat cheaper
    would be to use a SMD hot air rework station with a fine outlet, eg.

    There is a tip available 2.5mm

    You may be able to extend the small outlet for a cooler airflow and
    recalibrate the readout temp to correspond to the blow temp.

    I have a similar unit which I have, as a last resort, used to fault find
    temp sensitive faults, but I didn't need to know the air temp precisely
    to generate the fault condition.

  7. Bob Larter

    Bob Larter Guest

    Just use your soldering iron - carefully!
  8. JB

    JB Guest

    When it fails, troubleshoot and replace the bad part? Search for 2 hours on
    the Internet? Did you land a big contract to evaluate the thermal design of
    the UUT?
  9. Jim Yanik

    Jim Yanik Guest

    spray coolant onto Q-tip swab,press swab against suspect component.
    repeat as needed.
  10. GregS

    GregS Guest

    That would work. I was thinking of a dry ice stick. How about
    a thermal electric stick ? You could also make a TE air stick.
    Works in either heat or cold mode.

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