Problem in step 5
  • Hello I have a problem in step 5
    When I measure with the red dots GND my reading is good 4.98, but
    When I measure GND with green spots, do not mark anything
    I can do?
  • Check it the LT1054 is inserted the right way (Notch/Dot to the right!)

  • 4.97 reading is red
    0.63 green
  • What are the voltages at pin 5 and 8 of the LT1054?

  • Black GND to pin 5 0.14
    Black GND to pin 8 6.87
    change the power adapter and 9 volt reading changes to Black GND to pin 8 8.23
  • So the LT1054 is not generating a negative voltage. Is the LT1054 inserted the right way? Are all the capacitors around it correctly soldered?

  • capacitors are good soldiers
    and LT 1054 is positioned correctly
    I can do
  • Check the LT1054 and the Eprom aren’t mixed up? :)

    Or the optoisolator?

    I imagine (I can’t remember) that the guide and parts are nicely compartmentalised to stop people making the mistake, but things do happen.

  • with the Eprom, you mean the socket, which is housed lt 1054
  • Hello I have a problem in Step 5 When I measure with the red dots GND my reading is good 4.98, but when I measure GND with green spots is 0.63 reading
  • As I have said, there is a problem with the LT1054 or one of the parts around it. Please post of photo of the board, maybe we can spot the problem!

  • I agree to take a picture.
    Should I buy a new 1054 Lt
  • Oh, it’s simpler than that… It looks like you have swapped the capacitors.

    The 4.7uF capacitors are soldered in place of the 100uF capacitors.

  • capacitor C11 has changed the polarity
    what you mean
  • You have not checked the value written on the capacitors!

    You have soldered the 4.7uF capacitors in place of the 100uF capacitors.

    You have soldered the 100uF capacitors in place of the 4.7uF capacitors.

    The LT1054 needs a 100uF capacitor for C2. The capacitor you have soldered there is 4.7uF

  • now I just realized
    sorry I'm a newbie
  • I just correct the mistakes and still giving the same readings.
  • have you checked the polarity of the tantalum cap? I’ve never done this mistake before – but maybe it could have damaged the LT1054 :/ ?

  • as I check it?
    I do not understand
  • There’s a little row of +++++ on the positive side of it to mark the positive lead.

  • you should post a picture of the “copper side” of the board also, with a good quality if possible.

  • NEw picture I
  • New picture II
  • Now¡¡¡¡
    I just checked the polarity of the tantalum capacitor and is securely
    as I can see if the LT 1054 is broken?
  • Well, i have some doubts about a lot of your solder joints, even though we can’t see much on this picture (really, a higher resolution would be appreciated for this kind of picture).
    Anyway, solder joints should look smooth and bright, here i have the feeling that some of them are pretty messy.
    If not the case, you might consider using a lead solder, maybe yours is lead-free (which is a bit harder to work for the diy).

    I don’t know any way of testing a lt1054 but using a breadboard, or at least a “probe” circuit.

  • thanks'll change the lt1054 to see if that's the problem
  • Always worth checking the joints from the side, if their shape looks like mountains then they’re okay. If their shape looks like toffee apples then they’re duff.

    I agree about lead free solder, I don’t use it either.

  • I changed the component LT1054 and the measures are still bad, I can make q
  • juanico54 said:

    @Hello I have a problem in Step 5 When I measure with the red dots GND my reading is good 4.98, but when I measure GND with green spots is 0.63 reading @

    FYI, last night I was getting these exact same readings on an SMR-4 board I was troubleshooting and putting in a new LT1054 fixed everything.

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