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Sony SMD-HS73

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    #61
    Re: Sony SMD-HS73

    Ok, here is the closeup of of the U1 area.

    Also, since I've left it on a while, it is now having the lamps on for a longer time frame. Pin 5 is at about 5.4VDC when the lamps are on.
    Attached Files
    Last edited by torin3; 12-12-2010, 04:11 PM.

    Comment

      #62
      Re: Sony SMD-HS73

      Really nice photo. Let me verify the following:


      Whether you have a flickering OR a blank screen, you have a steady 5V and 12V output from the power supply? Correct?

      Very odd, since you seem to have fluctuating voltages reaching the OZ960.

      Hint: one method of determining which points are connected on a circuit board is with the power off and system unplugged, set your DMM to resistance or continuity and probe the various points. Zero ohms will indicate a short or continuity between those two points. It's not a super accurate method, since you might pick up readings from nearby resistors, but minus a schematic, it's much better than trying to "eyeball" the circuit.

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        #63
        Re: Sony SMD-HS73

        Originally posted by jetadm123 View Post
        Really nice photo. Let me verify the following:


        Whether you have a flickering OR a blank screen, you have a steady 5V and 12V output from the power supply? Correct?
        When it is blank, the 5V is around 4.9V, and when the lamp is on, it is around 5.1V.

        However, the 12V rail is about 12.25V when the lamp is on. But when the lamp is *OFF*, the voltage is between 16.5V and 17V!!

        Very odd, since you seem to have fluctuating voltages reaching the OZ960.

        Hint: one method of determining which points are connected on a circuit board is with the power off and system unplugged, set your DMM to resistance or continuity and probe the various points. Zero ohms will indicate a short or continuity between those two points. It's not a super accurate method, since you might pick up readings from nearby resistors, but minus a schematic, it's much better than trying to "eyeball" the circuit.
        Thanks for the technique. With the 12V rail is acting weird, any suggestions on what to look for in regards to that? I'm planning to start by checking components I can see that are touching the 12V traces and go from there.

        Comment

          #64
          Re: Sony SMD-HS73

          The 5V output is regulated, which is why you see so little movement under load. However, the 12V output is unregulated and generally will be at a higher voltage until a load (ccfl circuit) turns on. Once a load is applied, the voltage will drop. 17V does sound a little high, but not totally unusual. One way of checking is measuring the voltage output directly from the diode packs. These are the two devices mounted on the heatsink on the right side of your board. One device outputs 5V and the other 12V. Measure the middle pin of each device for voltage output. Be careful not to short the legs together!

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            #65
            Re: Sony SMD-HS73

            Originally posted by jetadm123 View Post
            The 5V output is regulated, which is why you see so little movement under load. However, the 12V output is unregulated and generally will be at a higher voltage until a load (ccfl circuit) turns on. Once a load is applied, the voltage will drop. 17V does sound a little high, but not totally unusual. One way of checking is measuring the voltage output directly from the diode packs. These are the two devices mounted on the heatsink on the right side of your board. One device outputs 5V and the other 12V. Measure the middle pin of each device for voltage output. Be careful not to short the legs together!
            The one closer to the top is the 5V one, and the one closer to the CCFL lamp plugs is the 12V. Same readings as I get at CN1. 4.9V lamp off, 5.1V lamp on. 17V lamp off, 12.25V lamp on.

            Comment

              #66
              Re: Sony SMD-HS73

              Originally posted by torin3 View Post
              The one closer to the top is the 5V one, and the one closer to the CCFL lamp plugs is the 12V. Same readings as I get at CN1. 4.9V lamp off, 5.1V lamp on. 17V lamp off, 12.25V lamp on.
              Weird, the original measurement for D12 was 13.81V and now it is 17V DC?
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                #67
                Re: Sony SMD-HS73

                Originally posted by retiredcaps View Post
                Weird, the original measurement for D12 was 13.81V and now it is 17V DC?
                Yeah. Is it possible that whatever is causing the problem is getting worse?

                Or maybe when I had the short that blew the fuse it damaged something else as well?

                Comment

                  #68
                  Re: Sony SMD-HS73

                  Originally posted by retiredcaps View Post
                  Weird, the original measurement for D12 was 13.81V and now it is 17V DC?
                  Great observation! Since both diode packs take their output directly from the transformer, I wonder if the transformer is starting to go bad? With power off, try checking D12 for shorts.

                  Comment

                    #69
                    Re: Sony SMD-HS73

                    Originally posted by jetadm123 View Post
                    Great observation! Since both diode packs take their output directly from the transformer, I wonder if the transformer is starting to go bad? With power off, try checking D12 for shorts.
                    The screw to the right leg is .3 ohm. I'm having a hard time getting the probes in, so I'm pulling it out to test it.

                    Comment

                      #70
                      Re: Sony SMD-HS73

                      Part is: STPS10150CT http://www.datasheetarchive.com/pdf-...SA-603609.html

                      Black on A1 to Red on
                      K = out of range
                      A2 = out of range
                      Top tab = out of range

                      Black on K to Red on
                      A1 = 144ohms
                      A2 = 144ohms
                      Top tab = .3ohms

                      Black on A2 to Red on
                      A1 = out of range
                      K = out of range
                      Top tab = out of range

                      Black on top tab to Red on
                      A1 = 144ohms
                      K = .3ohms
                      A2 = 144ohms

                      Comment

                        #71
                        Re: Sony SMD-HS73

                        Another way to test this diode is to put your multimeter on diode test functionality.

                        Number the pins 1, 2, and 3.

                        1) red on pin 1, black on pin 2, record diode measurement
                        2) black on pin 1, red on pin 2, record diode measurement
                        3) red on pin 3, black on pin 2, record diode measurement
                        4) black on pin 3, red on pin 2, record diode measurement
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                          #72
                          Re: Sony SMD-HS73

                          Originally posted by retiredcaps View Post
                          Another way to test this diode is to put your multimeter on diode test functionality.

                          Number the pins 1, 2, and 3.
                          1) red on pin 1, black on pin 2, 297
                          2) black on pin 1, red on pin 2, out of range
                          3) red on pin 3, black on pin 2, 297
                          4) black on pin 3, red on pin 2, out of range

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                            #73
                            Re: Sony SMD-HS73

                            Originally posted by torin3 View Post
                            1) red on pin 1, black on pin 2, 297
                            2) black on pin 1, red on pin 2, out of range
                            3) red on pin 3, black on pin 2, 297
                            4) black on pin 3, red on pin 2, out of range
                            Looks like D12 tests fine.
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                              #74
                              Re: Sony SMD-HS73

                              Originally posted by retiredcaps View Post
                              Looks like D12 tests fine.
                              Ok. Putting it back in the board.

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                                #75
                                Re: Sony SMD-HS73

                                It almost sounds like the 12V and 5V outputs have somehow combined to produce an intermittent 17V? When you soldered in the new caps at the 5V and 12V outputs, did you observe correct polarity? Check for any solder bridges between the solder pads and traces.

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                                  #76
                                  Re: Sony SMD-HS73

                                  Originally posted by jetadm123 View Post
                                  It almost sounds like the 12V and 5V outputs have somehow combined to produce an intermittent 17V? When you soldered in the new caps at the 5V and 12V outputs, did you observe correct polarity? Check for any solder bridges between the solder pads and traces.
                                  Yep, correct polarity observed. The bottom of the board has + & - signs at each point and the caps are correctly oriented. I usually check about 3-5 times to make sure I've got it lined up right before soldering. And I tend to remove 1 cap and replace it before removing the next so I can double check the silkscreen polarity designs relative to the other caps. Probably overkill, but I'd rather not get one in backwards.

                                  Also, I'm having luck tracing that 5V line from U1. Though a 22ohm resistor at R13, and then through a 10kohm resistor at R15. Though a few jumpers until I get to transistor Q7 on the main side. I'm going to check in in a few second with my Omega HHM 95 DMM. The Crapsman DMM I'm using has a louder beep in continuity check mode, but I don't like how if you aren't in the right resistance range, it gives you bogus numbers, and it isn't always easy to tell when you are in the right band based off of it.

                                  Edit: using diode check (first number from the HHM95 meter, second from the Craftsman meter)
                                  Black 1 Red 2 = .294 - 253
                                  Red 1 Black 2 = .526 - 608
                                  Black 3 Red 2 = .578 - 626
                                  Red 3 Black 2 = 1.137 - out of range
                                  Last edited by torin3; 12-12-2010, 09:32 PM.

                                  Comment

                                    #77
                                    Re: Sony SMD-HS73

                                    Originally posted by torin3 View Post
                                    Also, I'm having luck tracing that 5V line from U1. Though a 22ohm resistor at R13, and then through a 10kohm resistor at R15. Though a few jumpers until I get to transistor Q7 on the main side.
                                    Ok, I must be tired. For some reason I can't retrace this again. I get lost. I found another pcontinuity path, but I get stuck at a component 2D3, marked KZP, and then at 90° in smaller letters P7.

                                    Edit 1:Ok, I figured out how I got to Q7. Though there are several paths that get me to small surface mounted components that look like transistors of some type.

                                    I'll try and mark up a photo of where I'm getting continuity.

                                    Edit 2: Here is the photo.
                                    Attached Files
                                    Last edited by torin3; 12-12-2010, 10:11 PM.

                                    Comment

                                      #78
                                      Re: Sony SMD-HS73

                                      Originally posted by torin3 View Post
                                      Edit: using diode check (first number from the HHM95 meter, second from the Craftsman meter)
                                      Black 1 Red 2 = .294 - 253
                                      Red 1 Black 2 = .526 - 608
                                      Black 3 Red 2 = .578 - 626
                                      Red 3 Black 2 = 1.137 - out of range
                                      Which diode are you testing above?
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                                        #79
                                        Re: Sony SMD-HS73

                                        Originally posted by retiredcaps View Post
                                        Which diode are you testing above?
                                        The one labeled Q7 on the top of the board. Markings are S 7142 (something that might be 11, II, H, or something else)2.

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                                          #80
                                          Re: Sony SMD-HS73

                                          Originally posted by torin3 View Post
                                          The one labeled Q7 on the top of the board. Markings are S 7142 (something that might be 11, II, H, or something else)2.
                                          For transistors (Q), I like to test them for shorts using resistance.

                                          Test pin 1-2, 1-3, 2-3. Any reading under 30 ohms suggests it is shorted.
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