HP W2408H No Power (Surge) Repair - Success

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  • jamalC
    Member
    • Sep 2015
    • 14
    • denmark
    #21
    Re: HP W2408H No Power (Surge) Repair - Success

    Originally posted by Davi.p
    Probably yes, supposed you power on che monitor only one time, the NTC is there to protect the diode bridge from Power surge due to high current requested to charge the big cap the first switching on.

    the monitor didnt poweroff

    so i soldered the sck 037 back.

    something I noticed: i can hear the high pitched sound (like capacitor charges?). and high pitched, i mean there is a ramp of the pitch going up (slow attack of the envelope)

    hey thanks for replies guys!!
    Last edited by jamalC; 09-19-2015, 12:53 PM.

      Comment

      • jamalC
        Member
        • Sep 2015
        • 14
        • denmark
        #22
        Re: HP W2408H No Power (Surge) Repair - Success

        Originally posted by budm
        SCK037: 15mm Dia.
        At room temp (25c) the resistance is 3 Ohms (Zero power, no current flow), full steady state current is 7A Max at 25C, at this current flowing the resistance will drop down to 0.091 Ohms. It is NTC so as the temp goes up when the current start flowing its resistance will go down.
        thank for the explaining, very usefull.

          Comment

          • jamalC
            Member
            • Sep 2015
            • 14
            • denmark
            #23
            Re: HP W2408H No Power (Surge) Repair - Success

            Originally posted by ryankam
            ... Found out it should have been reading 5 OHMs when cool. Replaced thermistor with 5 OHM resistor and the monitor powered up.
            im a bit puzzled why this guy says that this thermistor should be reading 5 ohm instead of 3??
            Last edited by jamalC; 09-19-2015, 12:51 PM.

              Comment

              • jamalC
                Member
                • Sep 2015
                • 14
                • denmark
                #24
                Re: HP W2408H No Power (Surge) Repair - Success

                i also went through all diodes and resistors, all are reading nothing suspicous.
                what is this guy i marked with a blue circle? it says some numbers on his back (0734 8178 y). what could his purpose be in this universe .) and how can i test him?
                Attached Files
                Last edited by jamalC; 09-19-2015, 01:07 PM.

                  Comment

                  • vinceroger69
                    Badcaps Legend
                    • Mar 2012
                    • 6714
                    • uk
                    #25
                    Re: HP W2408H No Power (Surge) Repair - Success

                    i think its a optocoupler but not sure how to test it though.

                      Comment

                      • jamalC
                        Member
                        • Sep 2015
                        • 14
                        • denmark
                        #26
                        Re: HP W2408H No Power (Surge) Repair - Success

                        Originally posted by vinceroger69
                        i think its a optocoupler but not sure how to test it though.
                        thx for the reply!

                        do optocouplers live long and strong?

                          Comment

                          • jamalC
                            Member
                            • Sep 2015
                            • 14
                            • denmark
                            #27
                            Re: HP W2408H No Power (Surge) Repair - Success

                            Originally posted by ryankam
                            .... Replaced thermistor with 5 OHM resistor and the monitor powered up. .....
                            just replaced thermistor with 5 ohm (2 * 10ohms in parrallel was reading 5.6) and they both blew up.

                              Comment

                              • stj
                                Great Sage 齊天大聖
                                • Dec 2009
                                • 30937
                                • Albion
                                #28
                                Re: HP W2408H No Power (Surge) Repair - Success

                                lol - because it probably pulled over 30w through them!

                                  Comment

                                  • jamalC
                                    Member
                                    • Sep 2015
                                    • 14
                                    • denmark
                                    #29
                                    Re: HP W2408H No Power (Surge) Repair - Success

                                    Originally posted by stj
                                    lol - because it probably pulled over 30w through them!
                                    aaahhh ...

                                      Comment

                                      • Davi.p
                                        Hobbist Tech
                                        • Sep 2009
                                        • 4275
                                        • Italy - Milan
                                        #30
                                        Re: HP W2408H No Power (Surge) Repair - Success

                                        Jamal maybe thermistor is not yor problem, it has a bit of resistance when you put the AC plug in but after it become as invisible, do some readings, for example in volt at the bigger capacitor, you must read about 320v. Use gloves for safety.

                                          Comment

                                          • budm
                                            Badcaps Legend
                                            • Feb 2010
                                            • 40746
                                            • USA
                                            #31
                                            Re: HP W2408H No Power (Surge) Repair - Success

                                            24 inch monitor, lest say you are drawing 2A (if it is really drawing that high, more likely to be around 1A or so) through 5 Ohms = 20W of power, so about 10W per resistor. How big are the 10 Ohms resistors?
                                            May be you still have bad circuits that is drawing too much current too.
                                            Last edited by budm; 09-19-2015, 04:33 PM.
                                            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

                                              • stj
                                                Great Sage 齊天大聖
                                                • Dec 2009
                                                • 30937
                                                • Albion
                                                #32
                                                Re: HP W2408H No Power (Surge) Repair - Success

                                                2a? with leds maybe, but not with rack of cfl's in it!
                                                this monitor is rated at 130w

                                                  Comment

                                                  • jamalC
                                                    Member
                                                    • Sep 2015
                                                    • 14
                                                    • denmark
                                                    #33
                                                    Re: HP W2408H No Power (Surge) Repair - Success

                                                    Originally posted by Davi.p
                                                    Jamal maybe thermistor is not yor problem, it has a bit of resistance when you put the AC plug in but after it become as invisible, do some readings, for example in volt at the bigger capacitor, you must read about 320v. Use gloves for safety.
                                                    i'll defo do this. thx

                                                      Comment

                                                      • jamalC
                                                        Member
                                                        • Sep 2015
                                                        • 14
                                                        • denmark
                                                        #34
                                                        Re: HP W2408H No Power (Surge) Repair - Success

                                                        Originally posted by budm
                                                        24 inch monitor, lest say you are drawing 2A (if it is really drawing that high, more likely to be around 1A or so) through 5 Ohms = 20W of power, so about 10W per resistor. How big are the 10 Ohms resistors?
                                                        May be you still have bad circuits that is drawing too much current too.
                                                        yea this is why im a newbee: i took the "usual" ones, you use with a breadboard.
                                                        but now i guess i will be ordering one(s) with +30W

                                                          Comment

                                                          • stj
                                                            Great Sage 齊天大聖
                                                            • Dec 2009
                                                            • 30937
                                                            • Albion
                                                            #35
                                                            Re: HP W2408H No Power (Surge) Repair - Success

                                                            breadboard? you mean 1/3w resistors!! damn that must have been fireworks - on a small scale.

                                                              Comment

                                                              • jamalC
                                                                Member
                                                                • Sep 2015
                                                                • 14
                                                                • denmark
                                                                #36
                                                                Re: HP W2408H No Power (Surge) Repair - Success

                                                                Originally posted by stj
                                                                breadboard? you mean 1/3w resistors!! damn that must have been fireworks - on a small scale.
                                                                hahahhahaha

                                                                  Comment

                                                                  • budm
                                                                    Badcaps Legend
                                                                    • Feb 2010
                                                                    • 40746
                                                                    • USA
                                                                    #37
                                                                    Re: HP W2408H No Power (Surge) Repair - Success

                                                                    Originally posted by stj
                                                                    2a? with leds maybe, but not with rack of cfl's in it!
                                                                    this monitor is rated at 130w
                                                                    Really! Lets see now, his line Voltage is 230VAC, so 2A = 460W!, 130W will be less then 1A. The unit also has PFC.
                                                                    Check your math, or how you say it, lacking?
                                                                    Last edited by budm; 09-20-2015, 12:55 PM.
                                                                    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

                                                                      • stj
                                                                        Great Sage 齊天大聖
                                                                        • Dec 2009
                                                                        • 30937
                                                                        • Albion
                                                                        #38
                                                                        Re: HP W2408H No Power (Surge) Repair - Success

                                                                        my math? i got the wattage from HP's specs page!

                                                                          Comment

                                                                          • budm
                                                                            Badcaps Legend
                                                                            • Feb 2010
                                                                            • 40746
                                                                            • USA
                                                                            #39
                                                                            Re: HP W2408H No Power (Surge) Repair - Success

                                                                            Originally posted by stj
                                                                            my math? i got the wattage from HP's specs page!
                                                                            Yeah, so 130W with 230V, how many Amp will that be?
                                                                            jamalC, is in Denmark.
                                                                            Do the math again.

                                                                            Hint P= I *E
                                                                            130W @230vac = 0.565A
                                                                            130W @120Vac = 1.083A.

                                                                            I would say that the original Thermistor was blown due to bad parts on the power supply board that he needs to carefully inspect.
                                                                            Last edited by budm; 09-20-2015, 03:01 PM.
                                                                            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

                                                                              • jamalC
                                                                                Member
                                                                                • Sep 2015
                                                                                • 14
                                                                                • denmark
                                                                                #40
                                                                                Re: HP W2408H No Power (Surge) Repair - Success

                                                                                Originally posted by budm
                                                                                I would say that the original Thermistor was blown due to bad parts on the power supply board that he needs to carefully inspect.
                                                                                hey. what do you mean original Thermistor? you mean mine or Ryans (who bought a new thermistor and it worked?

                                                                                  Comment

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