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Unknown capacitor.

Discussion in 'Datasheets, Manuals and Component Identification' started by Tha fios agaibh, Nov 9, 2018.

  1. kellys_eye

    kellys_eye

    4,284
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    Jun 25, 2010
    The manufacturers will have a comprehensive datasheet explaining the whole marking sequence. Most users will get by with the value/voltage alone. I note that he capacitor is an X2 class though (Google it!)

    You might get clue as to zener rating from the voltage rating of any smoothing capacitor close to it. Supplies such as 5V or 12V will be there most obvious/common answers.
     
  2. Tha fios agaibh

    Tha fios agaibh

    1,906
    600
    Aug 11, 2014
    There is only a 100uf 50v smoothing cap next to it (C3) which could be rated much higher than final voltage rail so that's not much to go on.
    What I was figuring is the opto interrupter ir diode probably draws about 15ma @ 1.2Vf and it has a 3.3k resistor in series with it.
    That'd put the supply voltage at about 40v.

    I will ponder the numbers before I give it a try.
     
  3. kellys_eye

    kellys_eye

    4,284
    1,145
    Jun 25, 2010
    I'd guess at 24V. Are there any other devices that have particular operating voltages such as a relay etc?

    24V because a 25V capacitor would be too close and the next 'level' up would be the 50V device.
     
  4. Ylli

    Ylli

    200
    37
    Jun 19, 2018
    I take it there are no numbers on the part that you can read.
     
  5. Tha fios agaibh

    Tha fios agaibh

    1,906
    600
    Aug 11, 2014
    Unfortunately not. You may right though, and its definitely a good idea to try some lower values first, but I can't square the math of why they use a 3.3k current limiting resistor with the isointerrupter led.

    From everything I read, the If of a ir diode needs to be at least 10ma and have a Vf of 1.2v. I can't see anything less than 33v allowing sufficient current for the led.
    ....That is unless my specs are way off.
     
  6. Tha fios agaibh

    Tha fios agaibh

    1,906
    600
    Aug 11, 2014
    I don't think so, I'll look again tomorrow.
    Thats one downside to having tiny components.
     
  7. kellys_eye

    kellys_eye

    4,284
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    Jun 25, 2010
    Got the spec of the opto-coupler? A minimum value of 10mA for If seems quite high to me.
     
  8. Tha fios agaibh

    Tha fios agaibh

    1,906
    600
    Aug 11, 2014
    I believe this is it. It has an absolute max of 60ma, and draws 20ma with a typical 1.2v. Screenshot_2018-11-13-15-56-57-1.png
     
  9. kellys_eye

    kellys_eye

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    Jun 25, 2010
    That's only one page of the datasheet - isn't there a page (graph) that shows transistor saturation versus LED If?

    It shows collector current of 0.25mA at an LED If of 20mA. What resistor do you have in the collector of the optocoupler on that board? Sure the 3k3 resistor you quoted above isn't the collector resistor rather than the LED resistor?
     
  10. Tha fios agaibh

    Tha fios agaibh

    1,906
    600
    Aug 11, 2014
    Screenshot_2018-11-13-16-46-51-1.png Screenshot_2018-11-13-17-08-46-1.png
     
  11. Tha fios agaibh

    Tha fios agaibh

    1,906
    600
    Aug 11, 2014
    No, the 3k3 is in series with cathode of led side. Then the Anode of led goes to the collector of transistor collector(switch side) and a smd transistor. The emitter (npn) has a 10k in series with it.
     
    Last edited: Nov 13, 2018
  12. Tha fios agaibh

    Tha fios agaibh

    1,906
    600
    Aug 11, 2014
    I don't see it but does this help? sat7-48-08-1.png

    If supply was only 24v the current the led would see would be just under 7ma at the typical 1.2v forward voltage, correct?

    (given that it has a 3k3 current limiting resistor)
     
    Last edited: Nov 13, 2018
  13. Bluejets

    Bluejets

    3,453
    698
    Oct 5, 2014
    Might pay to do a quick check on C4, appears to be something with the firing of the MOC3062 opto triac chip.
     
  14. Tha fios agaibh

    Tha fios agaibh

    1,906
    600
    Aug 11, 2014
    Sorry, I was able to read markings on the zener. I think its a BZX 85c15
    which is a 15v. How does this make any sense? Only 4ma to power led?
     
  15. Tha fios agaibh

    Tha fios agaibh

    1,906
    600
    Aug 11, 2014
    Thanks but C4 is fine.
    It's probably good to go with a replacement zener, I just want to understand why its voltage is so seemingly low.
     
  16. kellys_eye

    kellys_eye

    4,284
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    Jun 25, 2010
    Unless you know the CTR (current transfer ratio) of the opto coupler you'll never know - although you could do tests to figure it out......

    Either way 15V sounds ok (it's a 1.3W zener) and 4mA isn't 'wrong'.....
     
    Tha fios agaibh likes this.
  17. Tha fios agaibh

    Tha fios agaibh

    1,906
    600
    Aug 11, 2014
    To clarify, this is an optointerrupter, (photo switch) not an optoisolator. I hadn't considered ctr to be a factor on something like this with two separate devices separated with a big gap and presumably independent of each other.
    Besides, wouldn't a larger ctr require more input current than specified in data sheet to compensate?

    If ps is 15v, led Vf is 1.1v and current (If) is 4.2ma it would match with the graph but it seems to just barely be enough to turn it on. Although I'm not exactly clear what the min would be according to the data sheet to turn it on. If 1.2v is typical Vf and draws 20ma, I'd expect the circuit to be design a little colser to that.

    Thanks kellys_eye ...et al, I do appreciate your time and willingness to share your brain with less knowledgeable folks like me.
     
  18. Bluejets

    Bluejets

    3,453
    698
    Oct 5, 2014
    Sorry, missed the bit way back where you found it shorted.
    I was close though... :)
     
  19. 73's de Edd

    73's de Edd

    2,678
    1,085
    Aug 21, 2015
    Thir Tha fios agaibh . . . . . . .hmmmmmmmmm I seem to have developed a . . . lissssssspth . . . make that Sir

    As best as I am able to " read " that Green on Green board foil layout and with very limited viewing of the push on wire stakes symbolization, this now seems to be my initial inclination of the circuit functions on your friends
    " Magnificent Milking Machine " circuit board.
    (Ewwwwwww that certainly smarts their udders tits ! . . . . . but milk volume increase is FANTASTIC ! )

    INITIAL ANALYSIS . . . . .

    Switching between relevant board view sides . . .starting at

    BOTTOM LEFT CORNER . . . . .

    AC line power is coming in, with its COLD side going to the DARK GREEN and it's HOT side going to the PALE GREEN which immediately reroutes out thru the ORANGE STAR and thru the units MAIN POWER SWITCH which has its other lead connected to the switched HOT area at the RED STAR up above.

    That area has HOT AC power routed to the hefty triac that does power switching to what I initially suspicioned, as being a HEFTY solenoid, but by only seeing the MO..... , has made me think of a geared down, high torque universal motor being used instead .
    Then, IF there is being gate drive to the triac from the MOC3062 driver, which gets its drive from the sole discrete SM transistor at the top of the board.. . . . the units punch action is done.

    Since the board is being all sealed away from being touched by a consumer/user, they have opted for an economical solution of the derivation of the units low voltage power for the semis, with a capacitive dropper design of circuit.
    The capacitive reactance along with a sometimes used " fine trimming " resistor reduces the resultant AC voltage reaching the Full Wave Bridge, which then DC charges the main C3 filter above. Then finally there is usually a dropping resistor feeding a Zener diode shunted across the circuitry for final upper voltage limit regulation of the supply . . . . sounding like your 12VDC . . . but I see that the main filter was liberally rated on upwards of 50VDC.
    AND do I see just the very top 5% of " ZD1 " symbolization, just barely peeping out, at the top, above the main DC filter cap ?

    HOUSTON . . . .we have power up ! . . . stand by for sequence of operations . . . .

    Now I need some observation, on your part . . . . . to fill in on the PURPLE mark-up white 2 pin MOLEX which has one PIN being with full DC power and the other PIN being routed into the two PINK transistors discrete circuitry.

    Also there is being the Optical INTERRUPTER' s function..

    Let's make this my initial stab . . .

    Consider that the O.I.. is being for a go no go or validating function.
    Like the actual papers presence into the machine, has to physically engage a mechanical "shutter" to the O.I. to validate the unit working, and thereby not " shooting blanks " punch operations.
    So that, a completed punch operation might activate the O.I.

    If that is the case , the white MOLEX might be related to an ACTIVATE function, such that if you move paper into proper place, and the paper presses into a microswitch that engages a punch operation .

    If the last is the situation, I am suspicioning that the shorted microswitch is feeding into the 2 pin MOLEX which ties into the 2 SM transistors discrete circuitry, which are configured as a timed one shot .
    It is then using the two PINK transistors and the PINK BAR timing capacitor to activate the MOC driver transistor for that DURATION of required rev up operation of the geared motor to do a punch.

    HOWEVER . . . .this might be all reversed, with the O.I. doing this job . . .thereby the need of your electro-mechanical observations and defining feedback.

    INITIAL TESTING . . . . . . .
    Confirm power at the top collector tab of the end of board MOC driver transistor as referenced to power supply power ground at the MAIN filter cap and then enact a punch action to see if a voltage swing occurs with that action.
    If so, then proceed to the MOC secondary . . . . on the HOT AC side . . . and and see if drive is being sent to the triac gate.

    ADDENDA . . . .
    Just now read-ed-ed back, and caught that . . . .That black thing U2 (3rd picture) is a photo switch that senses when the punch carriage returns. . . . . . in the very fine print of the contract.

    PLUS . . . the MOC primary DC supply path is . . . .
    Power comes left from + of FWB and up and into one pin of the MOC and passes thru the MOC primary and out into a ? value SM resistor and then ends at the collector of the discrete driver transistor.

    ALSO . . . . check the voltage at the + of the FWB to see what voltage level it is as referenced to the filter minus.

    BECAUSE . . . . they may have used a stacked supply , such that a higher voltage is being there (remember the 50V rating of the cap ) instead of ANOTHER lower voltage that the are deriving by holding the 12 VDC above ground, for deriving its second supply level (12VDC).
    So . . . . if you find 12VDC across the ZD1 and a HIGHER +DC voltage at the FWB + connection, that is exactly what they are doing..



    Thaaaaaaaaaaaasssssssssssssit . . . .'fer now

    SCALED COMPARATIVE BOARD LAYOUT . . . . . . .


    [​IMG]



    73's de Edd
    ......................



    ALWAYS REMEMBER ! . . . . . . this timely tip . . . .
    It is far, far better to break wind, and then head INTO the wind, than to break wind and head downwind.
     
    Last edited: Nov 15, 2018
  20. hevans1944

    hevans1944 Hop - AC8NS

    4,214
    1,994
    Jun 21, 2012
    Yup. Put that right up there with not tuggin' on Superman's cape or pullin' the mask off the old Lone Ranger...
     
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