Power supply problem
  • GateGate
    Hello everybody,

    i wanna build togehter the smr4 mk II v0.1 filterboard and at step 5 "power supply testing" i have 0,28 V on the red point and 0,08 V on the green probe point.
    Can anybody help me.

    regars
  • pichenettespichenettes

    What is the voltage on the wire jumper labelled “SW” (ie, what is the voltage delivered by your power supply?).

    Looks like your supply is AC, badly polarized, or has a voltage too low for the regulators to operate correctly.

  • GateGate
    I didn´t found a wire jumper in the kit. But in the picture i saw a littel wire (self made), like a bridge. This is what i made too.
    The power supply delivering 9 V.
  • GateGate
    I have a 3-12 V VDC 600mA

    And if i probe this, there 9 V.
  • GateGate
    Picture 1
  • GateGate
    Backside
  • fcd72fcd72

    You will have to bridge these two MS Pads….. i can’t see from the Pic if you really did.

  • pichenettespichenettes

    Could you please post the voltage read at the pads labelled I / O and + (-) of the 7805 and the 7905?

  • GateGate
    There is no bridge in the first picture...so what can i take for this?
  • JojjelitoJojjelito

    Use a resistor leg (or any component leg) from something you cut.

  • GateGate
    7905 = -0,03
    7805 = 0
  • GateGate
    black probe at + and red probe a -.

    sorry...i´m a really beginner.
  • fcd72fcd72

    Its really easy: if you don’t bridge the two Pads labeled MS (= Master Switch) it is exactly the same as if you had a Switch and set this to the OFF Position.

    In General most Synths work better with Electricity.

    BTW, the Black Probe always goes to Ground (GND) and you measure with the red one.

  • GateGate
    Ok...the MS is bridged.

    7905 = -0,3
    7805 = 0
  • pichenettespichenettes

    Voltages are always measured with respect to a reference. You need to put the black probe of the meter on what you want to be your reference, and the red probe on the point whose voltage, respective to the chosen reference, had to be measured.

    In this case, I want to know the voltages at pins, I, O, + of the 7905 and I, O, – of the 7805. These are 6 voltages to measure, all of them relative to the GND pad.

  • GateGate
    Measure of DC Connector 8,93 V and at the MS bridge 8,93.

    I continue to be something as a while ago.
  • GateGate
    ok...i understand.

    7905 I = -0,3
    7905 O = 0
    7905 + = 0

    7805 I = -0,2
    7805 O = -0,2
    7805 - = 0

    in reference to gnd
  • GateGate
    oh...i see now i have changed the 7905 to 7805 and the 7805 to 7905..shit.
    i thought they are both the same.
  • fcd72fcd72

    Must be a reason they are labeled different….. ;-)

    Everybody that never swapped a Part raise Hands! None?.....

  • GateGate
    yeah...at the digiboard are beautiful red circles und numbers on the picture... :-)

    but i think nothing is lost...only more work. :-)
  • 6581punk6581punk

    Have fun desoldering them, they’re possibly the worst things to get out :)

  • JojjelitoJojjelito

    Oy ve! I got off easily since I thought I know this after having built lots. My first Shruthi worked fine, but I mixed up some capacitors even though I was being careful and measured everything before soldering. Or so I thought…

    Good thing you spotted it. Have fun!

  • GateGate
    they are out...and now they are in, but the hole was close. I soldered it above but the measure is the same.

    Is it damaged now???

    So there must be a new filterboard and the few parts...i think positive...the board and the parts are cheap.
  • 6581punk6581punk

    The hole was closed? the hole in the board? you need to use a solder sucker or some wick (sucker is usually best) to clear out the holes.

    Sometimes you need to add a bit more solder to the joint to get it to clear easily.

  • schrabschrab

    If there’s no sucker and wick won’t help: put the PCB in one hand, soldering iron in another. Melt the solder with iron and quickly hit the board flat side on the edge of the table. Solder will fly out of the hole.

  • GateGate
    yes, the hole in the board (6 holes).
    I have a solder sucker...but i don´t know if it works.

    Now the 7905 and 7805 are on the right place (not during the holes but above the closed holes, works it?)...but the same measure.
  • GateGate
    which measure should be at this six points?
  • GateGate
    I´m from frankfurt if anybody from germany too.
  • fcd72fcd72

    *handheb

    YOu can also use the neddel from a syringe to push the melted Solder out of the Hole. The Solder won’t stick on the stainless steel needle.

  • GateGate
    das geht alles...aber die löcher sind dann zu klein um die dicken Stäbe der Teile wieder rein zu bekommen.
  • fcd72fcd72

    yo gate, you can eMail me anytime in German but here we strictly stick to english else BAAAAD THINGS ARE GONNA HAPPEN!!!

    I always have 0,5mm, 0,8mm and 1,2mm needles on stock – the girl in the Pharmacy every time looks like if i was a junkie until i recently showed her my arms ;-)

  • pichenettespichenettes

    > which measure should be at this six points?

    7905:
    O: -5V
    I: -9V (might change depending on your power supply, but should be in the -12 .. -7 V range)
    +: 0V (grounded)

    7805:
    O: 5V
    I: 9V (might change depending on your power supply, but should be in the 7 .. 12 V range)
    -: 0V (grounded)

  • schrabschrab

    @fcd72
    Haha! When i buying lye and acetone clerk at hardware store looks at me same manner =)

  • GateGate
    Oh sorry!

    I write you an email.

    And thank you all for the support.
  • GateGate
    if there other measures...where is the mistake?
    How can i find out?
  • pichenettespichenettes

    Have you check for shorts between adjacents pins of the regulators? You should at least see I: 9V on the 7805, because it’s directly hooked to the power supply.

    Which voltage do you have on the “I” pin of the 7805?

  • GateGate
    7805 I = 0
  • pichenettespichenettes

    So 9V at SW?, but nothing at I? Maybe you have soldered the protection diode backwards?

  • GateGate
    The white stripe is correct. Where the white strip is are 0 V and on the other side close to the DC connector, however, are 9 volts.
  • pichenettespichenettes

    Is there a way for you to change the polarity of the power supply? Maybe you are measuring backwards and the power supply has the wrong polarity?

  • GateGate
    i can change between 3 till 12 V.

    I thought i need 9 V, not?
  • pichenettespichenettes

    9V, yes, but what about the polarity?

  • GateGate
    The polarity is + o -
  • GateGate
    http://www.conrad.de/ce/de/product/518370/VOLTCRAFT-USPS-600-STECKER-SCHALTNETZT/SHOP_AREA_17455&promotionareaSearchDetail=005
  • LindeborgLindeborg

    If you put the black probe on outside of the barrel connector from the power supply and the red on the inside, does it say +9V or -9V?

  • GateGate
    it say - 8,92 V
  • LindeborgLindeborg

    Ah, then you have negative centre. See what happens if you remove the round barrel connector (hohlstecker) from the flat-ish power supply cord connector, rotate it 180 and put it back on the cord connector.

  • GateGate
    ok...now i have 4,56 V on the protection diode and 3,45 V on the 7805 I....and it was getting very hot so i had to pull the supply off.
  • GateGate
    oh...i see there two connectors of the 7805 soldered.
    the reason of getting hot?
  • GateGate
    embarrassing!
  • GateGate
    IT WORKS...all measures (- 5 at green und + 5 at red points) corect.

    Thank you for walking this way with me!
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