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Weller PU81 Soldering iron

Discussion in 'General Electronics Discussion' started by Mrbiccies, Dec 24, 2015.

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  1. Mrbiccies

    Mrbiccies

    4
    0
    Dec 24, 2015
    Hi guys, I have a faulty soldering iron! It is a Weller PU81 with a WSP80 iron that has very little use in it's 4 years life, The green led doesn't light up and the tip won't heat up? I've checked the power supply across Prim and Sec of the transformer and its ok. The cct board looks ok with no obvious burnt components, diodes checked out ok.
    I looked for a pin layout for the WSP80 with no luck.

    Any Ideas folks?

    Thanks in advance. Andy.
     
  2. 73's de Edd

    73's de Edd

    2,775
    1,159
    Aug 21, 2015
    .



    Mistah biccles . . . . . . . . .


    This unit typically takes about 15 seconds from cold to being at soldering temperature

    Considering that the main unit looks good and that the unit is putting out 24VAC to feed to your unit, lets look at its supposed schematic below:



    [​IMG]


    There seem to be 2 unused terminals of the 7 pins available on the WSP 80 X1 connector shown, so lets attack a given, and short one ohmmeter lead
    to the shell of the iron and use the free ohms lead to seek out the associated pin 5 of all of the mystery pins numbering assignments. That may then
    establish some credibility of the sequence of the layout of all of its other pins numbering s.

    Pins 1 and 3 are the receptors of the 24 VAC which heats your irons element. Seek out ~ 7 ohms for it.
    A thermal sensor gets connected between pins 3 being its ground and pin 4 being its feedback to the temperature control pre amp IC.
    Seek out ~ 22 ohms for it.

    With your heater element pins now identified you can go to those pins 1 and 3 and associate those with the receptacle in the main unit that it plugs into,
    and track those two pins to the units companion male / female connector ? backside terminals where they solder to wiring that passes over to internal circuitry.
    AC voltage monitor those pins . . . .then . . . .

    You power up the main unit , run the temp control to max and do a voltage check to see if 24VAC is present for your irons heater. if not, and with
    the WP80 Irons heater element and the temp sensor having testing good earlier, your main unit must have a fault.

    Go ye forth, and see what your situation is . . . .. . . . .


    73's de Edd


    .
     
    dennis78 likes this.
  3. 73's de Edd

    73's de Edd

    2,775
    1,159
    Aug 21, 2015
    Correction:

    Pins 1 and 3 are the receptors of the 24 VAC which heats your irons element.

    Should be:

    Pins 1 and 2 are the receptors of the 24 VAC which heats your irons element.

    The 24 VAC comes in to pin 1, flows thru the heating element and exits from pin 2, which passes to the Triac
    and completes a path to ground at such times that the Triac is turned on.

    73's de Edd
     
  4. Mrbiccies

    Mrbiccies

    4
    0
    Dec 24, 2015
    Thanks for you reply 73's de Edd and a Merry Christmas to you!

    I did have a measure around the pins before seeing your reply and can confirm the 7 ohm for the heater was present, I did not see 22 ohms though but did measure 1.7kohms! maybe my problem......
    I'll have a proper look armed with the schematic as soon as I'm allowed to!
     
  5. Mrbiccies

    Mrbiccies

    4
    0
    Dec 24, 2015
    Yep, 7 ohms across pins 1 & 2 (heater) and 1.7k ohms across 3 & 4 (sensor).
     
  6. Mrbiccies

    Mrbiccies

    4
    0
    Dec 24, 2015
    any thoughts 73's de Edd?
     
  7. 73's de Edd

    73's de Edd

    2,775
    1,159
    Aug 21, 2015
    I answered on your private conversation that you sent me
     
  8. 73's de Edd

    73's de Edd

    2,775
    1,159
    Aug 21, 2015
    .



    Mrbiccies . . . . . .


    From the sacrosanct words of Weller . . . . . .

    The use of precision Platinum (RTD – Resistance Temperature Detector) Sensors (WP80 / WSP80 / WMP, etc.)
    in the Soldering Handpieces, constitutes extremely long life while providing highly accurate temperature readings.


    ( Now doesn't that statement just warm your heart and think that the sensor PROPER is possibly NOT being the fault, since there is / are also interconnected wiring and interfacing connections !

    Hows about disassembling that unit, in order to get closer access of the inner temp sensor element and see if you can then individually "ohm out " between its two external connecting wires and the furthermost point that you can get to, within the unit, towards the units frontal platinum sensor.

    Considering its high temperature environs, they must have used either a crimp connection, a micro SILVER solder connection or a spot weld for their connection interfacing.

    Initially, was your testing of the "found" high resistance ( 1K+ . . .vice . . . approx 22 ohms) reading for the sensor being made at ITEM 7 connector or its connecting mate at the soldering station proper ?

    If so . . . . . retest at the Blue / or / Brown paired connections at the bottom pic of my illustrations.

    I don't know if this was being your iron from purchase day one or if it was an acquired used item, possibly coming from a production line.

    It is a known fact that a heavily used unit can develop metal flex fatigue of its internal wiring at repeated bend/stress points
    Soooooooooo after 'bouts eight tousands fo 'hunnerts and 'lebenteen times . . .thereabouts . . . an open wire connection can develop.
    See if this just might be your lucky day.

    If not . . . . .

    Referring to the illustrations :

    Differentiate between the Brown or Blue set of wires as to which is the heater wires and which are the sensor wires.
    Initially see if the sensor wires might just slowly pull out or, if they are being taut.
    Then see if working with inspecting A or B mechanical area might permit a further dis-assembly of the unit, for seeking out its interconnect wiring.

    [​IMG]




    ZUJ'ing

    73's de Edd
     
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