Help figuring out this circuit

Collapse
X
 
  • Time
  • Show
Clear All
new posts
  • predator0357
    Senior Member
    • Jul 2014
    • 159
    • Israel

    #1

    Help figuring out this circuit

    Hello friends,
    I need ur help figuring out what this and the parts and thats mark ones,
    P.S
    The IC is 555.
    Freind of mine working in some place that have the circuit and every time that it doesnt work his boss get mad cuz it cost him like 145$ and looked it n found this ic 555 and told my friend that his boss get mogded, and told him to tell his boss that i can fix it for ½ the price and i told my friend how much the ic cost (0.05$)and he told me great go do it u got ur self a side job.
    Attached Files
  • stj
    Great Sage 齊天大聖
    • Dec 2009
    • 31007
    • Albion

    #2
    Re: Help figuring out this circuit

    other side of the board?

    Comment

    • chozo4
      Nothing Special
      • Jan 2013
      • 134
      • USA

      #3
      Re: Help figuring out this circuit

      The one circled green is your generic ceramic disc capacitor. It looks like either 102 (1000pf) or 103 (10000pf) from that view. The other one in red looks to be a variable resistor with the value 20468? Thinking off hand it might be a 200k adjustable resistor meant for loads up to a max of 68ma but I'm likely wrong there.

      The small blue ball just under the edge of the green circle (unsure if that was also meant to be circled) would be a small inductor. Cannot tell the values in image however.

      Though I'm tired and running on practically no sleep..
      Observing the red/green LEDs, 555 with single inductor/capacitors in line with it I'm wagering it to be an adjustable charge circuit of sorts. Though it's missing the mosfet/transistor so might not be. No way to actually tell without seeing the bottom of the board as STJ states.

      One thing I don't understand is the statement of 'everytime it doesn't work the boss gets mad'. Shouldn't they prototype it first before production to ensure it works at least in a basic capacity? Would save a lot of headache.
      Last edited by chozo4; 08-03-2014, 03:49 AM.
      Even crap caps can be useful... such as blank rounds for prop gunfights.

      Comment

      • selldoor
        Slow Learner
        • Dec 2010
        • 7870

        #4
        Re: Help figuring out this circuit

        If you dont know what these basic parts are it was rather foolish to say you can repair it for half the price. I really think we need to know what it is off
        Please upload pictures using attachment function when ask for help on the repair
        http://www.badcaps.net/forum/showthread.php?t=39740

        Comment

        • stj
          Great Sage 齊天大聖
          • Dec 2009
          • 31007
          • Albion

          #5
          Re: Help figuring out this circuit

          whatever it is, it's junk.
          the problem with analog oscillators is the time is not constant because the capacitors are effected by temperature and aging.
          it may have been a valid design 20years ago,
          but these days i would have just stuffed the whole circuit into an 8pin 50c microcontroller.

          it's probably a pulse-stretcher btw,
          Last edited by stj; 08-03-2014, 05:42 AM.

          Comment

          • predator0357
            Senior Member
            • Jul 2014
            • 159
            • Israel

            #6
            Re: Help figuring out this circuit

            Originally posted by selldoor
            If you dont know what these basic parts are it was rather foolish to say you can repair it for half the price. I really think we need to know what it is off
            FIRST I KNEW WHAT THOSE PARTS ARE!!!!
            I know that small part is a cap i wasnt sure how to read it, and the second one in the red also i wasnt sure i knew its varible resistor (and my teacher said its a trimmer), and i said i can fix cuz 2 weeks ago in the class we did this exp.

            Comment

            • stj
              Great Sage 齊天大聖
              • Dec 2009
              • 31007
              • Albion

              #7
              Re: Help figuring out this circuit

              you read the trimmer like a surface mount resistor.
              the first 2 digits are what you see, the 3rd digit is the number of zero's on the end.

              so 204 = 200000 ohms or 200k

              not much to go wrong other than the chip.

              Comment

              • mariushm
                Badcaps Legend
                • May 2011
                • 3799

                #8
                Re: Help figuring out this circuit

                The 555 chip is like a timer. There's pretty much 3 typical modes of operation for that chip, which you can read about here : http://www.555-timer-circuits.com/operating-modes.html

                Take a piece of paper and draw the circuit on the piece of paper, then compare your design with the circuit for each of those typical three modes of operation.. you have examples at the link above, or you can search in google for "555 example circuits"

                Probably even the 555 datasheets have example circuits in them - the fact that you came here to ask for help tells me you probably didn't even bother to search for information in the first place.

                If the chip is running in a timer mode, you can use this page to figure out how
                much time is the 555 supposed to be on, and how much time it's supposed to be off: http://www.555-timer-circuits.com/calculator.html

                Then, you can compare expected results with what your board outputs and see if your 555 is faulty or not.

                ps. What's up with that green led lead, it seems to be shorting that diode and resistor together. See if that's intentional.

                Comment

                • selldoor
                  Slow Learner
                  • Dec 2010
                  • 7870

                  #9
                  Re: Help figuring out this circuit

                  Originally posted by mariushm

                  Probably even the 555 datasheets have example circuits in them - the fact that you came here to ask for help tells me you probably didn't even bother to search for information in the first place.
                  The OP is at school / college - I wonder if we are just doing his homework for him
                  Please upload pictures using attachment function when ask for help on the repair
                  http://www.badcaps.net/forum/showthread.php?t=39740

                  Comment

                  • predator0357
                    Senior Member
                    • Jul 2014
                    • 159
                    • Israel

                    #10
                    Re: Help figuring out this circuit

                    Originally posted by selldoor
                    The OP is at school / college - I wonder if we are just doing his homework for him
                    Hehehehehehehehrh no its not my homework, homework i like very much do it on my own without help and geting mistakes and learn from them.

                    Comment

                    • predator0357
                      Senior Member
                      • Jul 2014
                      • 159
                      • Israel

                      #11
                      Re: Help figuring out this circuit

                      Originally posted by mariushm
                      The 555 chip is like a timer. There's pretty much 3 typical modes of operation for that chip, which you can read about here : http://www.555-timer-circuits.com/operating-modes.html

                      Take a piece of paper and draw the circuit on the piece of paper, then compare your design with the circuit for each of those typical three modes of operation.. you have examples at the link above, or you can search in google for "555 example circuits"

                      Probably even the 555 datasheets have example circuits in them - the fact that you came here to ask for help tells me you probably didn't even bother to search for information in the first place.

                      If the chip is running in a timer mode, you can use this page to figure out how
                      much time is the 555 supposed to be on, and how much time it's supposed to be off: http://www.555-timer-circuits.com/calculator.html

                      Then, you can compare expected results with what your board outputs and see if your 555 is faulty or not.

                      ps. What's up with that green led lead, it seems to be shorting that diode and resistor together. See if that's intentional.

                      Tnx 4 the help:-)
                      And yes this is the firsst thing that i notice with the led, look my sent this pic and to day i asked from him to pic more of this.
                      Anc again tnx 4 the help and understanding

                      Comment

                      • budm
                        Badcaps Legend
                        • Feb 2010
                        • 40746
                        • USA

                        #12
                        Re: Help figuring out this circuit

                        BTW, is this being used to control other board/circuits? The more info we have the better.
                        Never stop learning
                        Basic LCD TV and Monitor troubleshooting guides.
                        http://www.badcaps.net/forum/showthr...956#post305956

                        Voltage Regulator (LDO) testing:
                        http://www.badcaps.net/forum/showthr...999#post300999

                        Inverter testing using old CFL:
                        http://www.badcaps.net/forum/showthr...er+testing+cfl

                        Tear down pictures : Hit the ">" Show Albums and stories" on the left side
                        http://s807.photobucket.com/user/budm/library/

                        TV Factory reset codes listing:
                        http://www.badcaps.net/forum/showthread.php?t=24809

                        Comment

                        • predator0357
                          Senior Member
                          • Jul 2014
                          • 159
                          • Israel

                          #13
                          Re: Help figuring out this circuit

                          Yes it controll a traffic Billboards that have on the same side 3 advertisement/Comercials and it control the time when the advertisement/Comercials turn to the second and the third and start over, the circuit working on 12[Vcc] DC( as i recall it turns every 8sec n when the 555IC doesnt work it wont turn and it happend when something jamming the billboard, not every time some time it just get fried:-) ).
                          Look this 555IC in this circuit is the weakes part, cap there is the second n third is resistors so as i see it, i want to build like 5 circuits like this one and add connector to the VCC+GND and when one of the billboard circuit get burned i will replace it with mine.
                          P.S
                          I knew its a 555 timer circuit but i love to hear others opinions cuz mayB some1 els see things that now i dont.

                          Comment

                          • stj
                            Great Sage 齊天大聖
                            • Dec 2009
                            • 31007
                            • Albion

                            #14
                            Re: Help figuring out this circuit

                            it's pretty shit using a 555 in free-running mode for such a long time duration.

                            if you must use this design, you need lots of protection from spikes and shit.
                            input capacitors, input spike supression using a transorb,
                            output buffering through a transistor with a fuse on it.

                            if you want real advice,
                            post a schematic of the whole setup.
                            the psu, the motor and driver including what i assume is a camswitch with diodes across it etc.
                            actually a plain camswitch would have done it in the past.
                            Last edited by stj; 08-04-2014, 04:13 AM.

                            Comment

                            • predator0357
                              Senior Member
                              • Jul 2014
                              • 159
                              • Israel

                              #15
                              Re: Help figuring out this circuit

                              Originally posted by stj
                              it's pretty shit using a 555 in free-running mode for such a long time duration.

                              if you must use this design, you need lots of protection from spikes and shit.
                              input capacitors, input spike supression using a transorb,
                              output buffering through a transistor with a fuse on it.

                              if you want real advice,
                              post a schematic of the whole setup.
                              the psu, the motor and driver including what i assume is a camswitch with diodes across it etc.
                              actually a plain camswitch would have done it in the past.
                              Hi,
                              Look i am not looking for new or better design, i am just looking for to remake this circuit to have spares for if one of the billboard get burned i will just come n replace the faulty circuit and then ill fix it

                              Comment

                              • stj
                                Great Sage 齊天大聖
                                • Dec 2009
                                • 31007
                                • Albion

                                #16
                                Re: Help figuring out this circuit

                                then post a foto of the trackside of the board!

                                Comment

                                • budm
                                  Badcaps Legend
                                  • Feb 2010
                                  • 40746
                                  • USA

                                  #17
                                  Re: Help figuring out this circuit

                                  You also need to remove that tape on the board so we can see verything, and we also need to know where those wires go to, it sounds like there is no transistor to drive the the load which may have exceed the 555 output drive capability.
                                  Never stop learning
                                  Basic LCD TV and Monitor troubleshooting guides.
                                  http://www.badcaps.net/forum/showthr...956#post305956

                                  Voltage Regulator (LDO) testing:
                                  http://www.badcaps.net/forum/showthr...999#post300999

                                  Inverter testing using old CFL:
                                  http://www.badcaps.net/forum/showthr...er+testing+cfl

                                  Tear down pictures : Hit the ">" Show Albums and stories" on the left side
                                  http://s807.photobucket.com/user/budm/library/

                                  TV Factory reset codes listing:
                                  http://www.badcaps.net/forum/showthread.php?t=24809

                                  Comment

                                  Related Topics

                                  Collapse

                                  • Astonished
                                    Fixing the Charge Circuit of the Batteries of the DC Motor
                                    by Astonished
                                    Hi friends of electronics

                                    What you see in the video and pictures attached is the circuit for charging the batteries of a DC motor.

                                    The problem is that this circuit cannot charge the batteries (3 1800mAH NiMH batteries) any more. When the circuit was OK, its green LEDs lit up one at a time to show that the batteries have charged more. But now that the circuit is flawed, LEDs light up as you see in the video and at the same time successive beeps are heard.

                                    Please help me fix this circuit.

                                    (the datasheet of the IC: https://pdf.datasheet.live/28...
                                    01-28-2025, 06:24 AM
                                  • rddube
                                    Lenovo L490 Ram voltage circuit malfunction
                                    by rddube
                                    Hello friends,

                                    Looking for some guidance here. The RAM voltage circuit on this motherboard keeps burning out PU301 which is a RT8231AGQW. Copy of the board with the burnt chip attached with some voltage measurements and copy of the schematics also included.

                                    I think I've checked almost every component in the circuit, but when I change the RT8231, the laptop starts I have 1.2V on the inductor for about 10 seconds and then the RT8231 goes south and no more voltage on the inductor. All other voltages on the laptop are good, this is the only one conking out for a reason I...
                                    07-15-2025, 04:41 PM
                                  • Tarot Superstars
                                    Short Circuit tester
                                    by Tarot Superstars
                                    Hello.
                                    I have seen a short circuit tester made with 3 * 9V batteries, a voltage limiter component and a resistor connected to the probes of a multimeter.
                                    The theory is that the meter becomes sensitive enough to read very low resistances and the lowest resistance to ground on a circuit is likely to be a short circuit in that area.

                                    Link
                                    The Amazing $1 Short Finder Upgraded! Convert ... - YouTube
                                    https://www.youtube.com/watch?v=0eixDdCpiO4

                                    My multimeter isn't normally sensitive to very small resistance, but when I put a 1 mega ohm resistor...
                                    09-25-2023, 09:11 AM
                                  • sam_sam_sam
                                    How an incandescent light and a ESR meter ** friend**have a machine blowing fuses
                                    by sam_sam_sam
                                    About a month ago we had a transformer jumper wire that burned in two different places between two transformers caused over $200 thousand dollars worth of damage to VFD drives at least 10 of them and a memory card and quite a few power supply as well

                                    Now we have most of the equipment that got damaged back up and running except a feeder that has issues and we are waiting for some parts for

                                    Now we also have another piece of equipment that was blowing fuses on the 110 volt controller switch circuit with the “E” stops and one switching power (24 volt) supply and a transformer...
                                    12-14-2023, 07:45 PM
                                  • M1NEBLANK SHOW
                                    MSI B250 Gaming M3 Short circuit in CPU power supply circuit
                                    by M1NEBLANK SHOW
                                    Hello. MSI B250 Gaming M3 board, short-circuit on the power supply. Found a problematic mosfet VQ1
                                    (N-PK616BA_PDFN8-HF) soldered it out - short circuit is gone. I replaced VQ1 + VQ5 (N-PK632BA_PDFN8-HF). VQ1 was replaced with PK618. After starting attempt VQ1 is lit again. What can be the problem? In the driver?

                                    Schematic and Boardview here
                                    ...
                                    04-04-2025, 03:57 PM
                                  • Loading...
                                  • No more items.
                                  Working...