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    Troubleshooting DAV-HDX265 no power

    Hi! I have a Sony home theater system that won't power up, model DAV-HDX265.

    It contains a power supply board 07dav-power-13-mp (1-872-105-13). I've checked a few things, but not sure where to go from here. Attached some pics, if any zoomed-in shots would help just let me know.

    - the voltage from CN904 marked 31.5vdc measures 0v
    - the voltages from CN906 don't make a lot of sense to me, but I'm not sure if I should be measuring from chassis gnd or "D-GND" on CN907...
    - I checked all electrolytic caps with an ESR meter, and nothing looks suspect; no caps bulging either
    - I checked the diodes and transistors, as well as IC921 for shorts but don't notice any
    - fuses/resistors F901, LF902, R912, R913, FR930, R903, R904, R927 all seem fine
    - for the heck of it I replaced C924 & C926 (I hate Lelon caps), but no change
    - I hear a faint, high-pitched squeal when the board is plugged in, not sure if that necessarily means anything

    I think I found the schematic here:
    https://www.manualslib.com/manual/59...page=64#manual

    Any help or advice on where to go from here would be greatly appreciated, thanks!
    -Chris
    Attached Files

    #2
    Re: Troubleshooting DAV-HDX265 no power

    What voltage are you measuring on CN906? Just use chassis ground. Or if you are working on just the power supply out of the unit, use pin 7,10 or 12. The voltage you need is 6Volts, (pin6), this will be the standby voltage

    If you don't have any voltages on CN906, check the voltage (carefull, this is the hot side of the power supply) across C903. If you have 160vdc.
    You can also check from the top of the board, Use JW986 for HOT ground and check the voltage on JW981, then keep the negative probe on JW986 check the voltage on both sides of R929
    Last edited by R_J; 08-18-2019, 12:27 PM.

    Comment


      #3
      Re: Troubleshooting DAV-HDX265 no power

      Thanks, RJ!

      > What voltage are you measuring on CN906? Just use chassis ground. Or if you are working on just the power supply out of the unit,
      > use pin 7,10 or 12. The voltage you need is 6Volts, (pin6), this will be the standby voltage

      Ah OK, I'm just working outside the unit, so using pin 7:

      1) P.CONT1: 0.0
      2) P.CONT2: 6.5
      3) P.CONT3: 0.0
      4) E+4V: 4.0
      5) D+3.3V: 0.0 * initially measured some voltage but gradually droppped to 0.0
      6) 6V: 8.3
      8) D+5V: 4.5
      9) M+8V: 8.0
      11) 12V: 9.7

      Across C903 I measure 167vdc. Between JW986 & JW981, and from JW986 to both sides of R929, I get 167vdc.

      Comment


        #4
        Re: Troubleshooting DAV-HDX265 no power

        It looks like the power supply is working, I would connect it back in. and see if it will turn on.
        Pin 11 & 8 are low because you need P.CONT1 to turn on ic941 & 943. When CN906 is connected to the main you should get 3.3 volts on pin1 P.CONT1
        You won't have the +31 volts until that part of the power supply is turned on.
        What you can check before you reconnect the power supply is to check the resistance between the pins 1 and 4 on CN3002. It should not read shorted.

        You can leave CN3002 disconnected and hook up the rest of the connections to the power supply and see if you get your +31 on CN904 of the power supply. If you get +31 with it disconnected but its 0 when it's connected, suspect a shorted output ic.

        I was looking at the picture of the bottom of the power supply board and although it's hard to tell from the picture, I would resolder the connections on both of the transformers. If you see the transformer lead and there looks like a black ring around it that usually indicates a poor connection.

        That P.CONT2 voltage seems high, Check what it is when the plug is connected to the rest of the unit.
        Last edited by R_J; 08-18-2019, 09:54 PM.

        Comment


          #5
          Re: Troubleshooting DAV-HDX265 no power

          >> before you reconnect the power supply is to check the resistance between the pins 1 and 4 on CN3002

          No short detected.


          >> It looks like the power supply is working, I would connect it back in. and see if it will turn on.

          Screwed in & plugged power board back in, leaving CN3002 disconnected, but still nothing on the display.


          >> Pin 11 & 8 are low because you need P.CONT1 to turn on ic941 & 943. When CN906 is connected to
          >> the main you should get 3.3 volts on pin1 P.CONT1
          ...
          >> That P.CONT2 voltage seems high, Check what it is when the plug is connected to the rest of the unit.

          Hmm... with CN906 connected to the main board (as well as CN903 & CN907), I see 0vdc on pin1 P.CONT1. I only get 4.0vdc for "E+4V" & 9.1vdc for "6V", all others measure 0vdc in the unit.


          >> You can leave CN3002 disconnected and hook up the rest of the connections to the power supply and see
          >> if you get your +31 on CN904 of the power supply. If you get +31 with it disconnected but its 0 when
          >> it's connected, suspect a shorted output ic.

          CN3002 disconnected I only see 0vdc. Tried pressing the pushbutton Power button on the front even though there's no display, but nothing changes.


          >> I would resolder the connections on both of the transformers

          Will do, I'll resolder the transformers and check again for any changes. Thanks!

          Comment


            #6
            Re: Troubleshooting DAV-HDX265 no power

            If the E+4V is ok, that 6V should only be 6v, if it is higher, it could be due to a bad C944, when they get weak they don't filter properly and can show a higher than normal voltage. The 4 & 6 volts come from the same transformer.
            You can check the other voltages from this section of the power supply at there supply diodes. D942 supplies 9.5v and D941 supplies 13.4v.

            Check on the main board for D504, It should have BU3.3 volts that supplies the microprocessor
            Last edited by R_J; 08-19-2019, 09:32 AM.

            Comment


              #7
              Re: Troubleshooting DAV-HDX265 no power

              Thanks! I resoldered the pins on both transformers, but didn't notice any cracked joints.

              >> that 6V should only be 6v, if it is higher, it could be due to a bad C944, when they get weak they don't
              >> filter properly and can show a higher than normal voltage

              I checked C944 and it tests fine, but replaced it anyway. Now measure 8.0vdc for CN906 "6V", but it slowly creeps up.


              >> You can check the other voltages from this section of the power supply at there supply diodes.
              >> D942 supplies 9.5v and D941 supplies 13.4v.

              D942 looks right at 9.4vdc, but not sure about D941 reading 19.9vdc.
              D944 shows 11.2vdc, if that one matters.


              >> Check on the main board for D504, It should have BU3.3 volts that supplies the microprocessor

              Reading this off the + lead of C527 (D504 must be on the bottom of the main bd), I see 3.6vdc.

              Comment


                #8
                Re: Troubleshooting DAV-HDX265 no power

                It's hard to say what to check next, the voltages for the main system control ic seem to be there, so when you push the power button, ic501 should see that command and outout 3.2v on P_CONT1 to turn on the rest of the power supply.

                You won't have a display untill you have D+5V, and to get that voltage IC942 needs to be enabled by P.CONT3

                You could check that ic503 reset voltages are correct and that there is 3.3v on Q503.
                Last edited by R_J; 08-19-2019, 07:07 PM.

                Comment


                  #9
                  Re: Troubleshooting DAV-HDX265 no power

                  Hi RJ, Thanks for the info! Sorry for the delay, things have been busy lately.

                  >> when you push the power button, ic501 should see that command and outout 3.2v on P_CONT1 to turn on the rest of the power supply

                  P_CONT1 stays at zero when pushing and releasing the power button.


                  >> You won't have a display untill you have D+5V, and to get that voltage IC942 needs to be enabled by P.CONT3

                  Indeed D+5V is not present (0.3vdc), and P.CONT3 stays zero as well.


                  >> You could check that ic503 reset voltages are correct and that there is 3.3v on Q503.

                  I notice ic501 VCC on pin 99 and others should be 3vdc per the schematic, and pin 99 shows 3.2vdc, so that's promising...

                  Here's what I see on IC503 (PST3635NR):

                  1) schem 3.3 OUT, measured 0 !
                  2) schem 3.9 VDD, measured 4.0
                  3) schem GND, measured 0

                  4) schem NC, measured 0
                  5) schem 3.5 CD, measured 3.6

                  Q503 shows 0.7, 0.2, & 0.0 on its 3 pins.


                  I measured IC503 OUT several times, holding my probe on while plugging the unit in, and waited at least 10 seconds, but I only see a low voltage there around 0.02v, I never see it change. Does that mean (a) IC503 is bad, (b) Q503 is bad, or something else?

                  Could I "trick" it by plugging it in and touching a 3v battery to the IC503 OUT to see if it turns on, or is that a bad idea?

                  Comment


                    #10
                    Re: Troubleshooting DAV-HDX265 no power

                    You could check the resistance of ic503 pin1 to ground just to make sure C521 is'nt shorted, if its not, it could be the ic is faulty, temporarily shorting pin 2 ~1 would accomplish the same thing but could damage the reset ic if it's not defective. What I would do is unsolder pin1 to isolate the pin, then with the unit on, short pin1 to ground and relaease it to see if the unit works.

                    If you short pin 5 to ground does that change the state of pin2?

                    If the reset is being held to ground the microprocessor will not run its program so will appear dead.
                    Last edited by R_J; 08-25-2019, 03:17 PM.

                    Comment


                      #11
                      Re: Troubleshooting DAV-HDX265 no power

                      Progress!

                      So, there were so many tiny components near IC503, that rather than lift pin 1 I just lifted the entire chip using my hot air station. Shorting pad 1 to GND does nothing, but shorting it to VDD makes the display come on! The demo mode starts doing its thing.

                      >> check the resistance of ic503 pin1 to ground just to make sure C521 is'nt shorted

                      I measured about 10K, so likely the IC is defective.


                      It looks like there's some more damage, but not sure how bad it is... when I press Power the display indicates FM Radio mode, and turning the Volume knob makes the number go up & down. However, I am unable to change the frequency. If I press the Function button or the DVD Eject button, after a second or two the unit powers off and blinks "STANDBY" on the display. Any thoughts where I should start looking?
                      Attached Files

                      Comment


                        #12
                        Re: Troubleshooting DAV-HDX265 no power

                        I would replace the reset ic, If you don't reset the microprocessor properly it might not start the program at the begining and then not function properly. The reset needs to be taken low, then high right after the micro gets vcc.
                        Locate Q503 & check the voltage on the collector, it should be 3.3 volts. Short the collector to the emitter for a second and see if it resets the micro. This will do a manual reset on the micro.
                        Last edited by R_J; 08-27-2019, 08:45 AM.

                        Comment


                          #13
                          Re: Troubleshooting DAV-HDX265 no power

                          Thanks RJ!

                          >> Locate Q503 & check the voltage on the collector, it should be 3.3 volts.

                          Yup, I see 3.2vdc.


                          >> Short the collector to the emitter for a second and see if it resets the micro. This will do a manual reset on the micro.

                          Yup! Display went off, then a few seconds came back on.

                          Unfortuntately, no change in behavior though :-P Pressing Function button or Eject cause the unit to flash "Standby" and power off.


                          >> I would replace the reset ic, If you don't reset the microprocessor properly it might not start the program at the begining and then not function properly.

                          Noted, I'll search for a replacement for the IC503. Some initial searches for PST3635NR not finding much, but I'll do a deeper search in a bit.

                          Comment


                            #14
                            Re: Troubleshooting DAV-HDX265 no power

                            Try doing a cold reset once the amp is on if you can (page 23 of manual) It seems like there is a protection problem, See page 24 Protection Factor
                            Last edited by R_J; 08-27-2019, 07:49 PM.

                            Comment


                              #15
                              Re: Troubleshooting DAV-HDX265 no power

                              Oh yeah, I tried that tonight actually... I think it was power on then press stop-eject-power buttons simultaneously, but it ignores the combination, similar to trying to change FM frequency displayed. I'll take a closer look at page 24 and post any developments, thanks!!

                              Comment


                                #16
                                Re: Troubleshooting DAV-HDX265 no power

                                I was refering to this:

                                You could try and locate Q3552 (page35,D-3) and check the voltage to see if the DC detect is 3.3v or 0v
                                Attached Files
                                Last edited by R_J; 08-27-2019, 08:34 PM.

                                Comment


                                  #17
                                  Re: Troubleshooting DAV-HDX265 no power

                                  Hi! Finally had some more time this weekend to poke around...

                                  The collector on Q3552 gives about 3.3 vdc when I first plug the unit in, but drops to 0. I notice pressing the Power button no longer makes this unit come to life, it just stays in demo mode regardless what buttons are pressed. Not sure what changed.

                                  I found another unit of the same model at a thrift store, shockingly also would not turn on... I picked it up anyway so I can have some parts to compare & swap.

                                  Unit #2 the power supply was completely dead, so I compared all components against unit #1 power supply, and finding different resistances decided to swap out both IC901 & IC921. Not seeing any bad caps, open resistors/fuses or other issues I plugged it in and unit #2 power supply seems good. Also the CN906 "6V" on unit #2 power supply measures 6vdc, compared to unit #1 which always seemed high. Plugged into unit #1 main board, all unit #2 power supply voltages come on for the first few seconds after plugging into the outlet, and all voltages look good, even 32vdc CN904.

                                  Putting power supply #2 back in unit #2, the unit came on the first time I pressed Power button. But when I pressed Eject it started showing "PROTECTOR" -> "PUSH POWER." Ever since, it shows that immediately after being plugged in, regardless of how long I let it sit. Shouldn't it go back to the Demo flashing mode after it sits a while? Did something on the main board kill itself the first time it tried to power up, or is some circuit remembering protection was triggered and I need to clear that somehow?

                                  I checked the outputs of each amp chip for any obvious shorts, but did not find any.

                                  Per the service manual (p24), holding Fn + Ej + FF displays "SD DETECT." I see a "SD" pin 4 on the Digital Power Amp IC's (p32 - 3100/3150/3200/3250/3300/3400/3500). These seem to feed Sys Controller IC501 pin 43, something called shutdown detection. I'm seeing 0vdc on this pin... I would expect to see 3.3vdc if there was an error...

                                  I notice each of these has a 0 Ohm resistor in series with each amp chip pin 4. I desoldered each of these 0 Ohm resistors in the hope it would come on since that would sever the detection pins from the amp chips, but I still see the "PROTECTOR" error. Both pads of each pin 4 resistor still measure 0vdc.

                                  I was hoping unit #2 would be an easier fix, but so far no luck :-P Any ideas what I could check next on either unit #1 or unit #2? If I can get one unit running that's good enough for me

                                  Comment


                                    #18
                                    Re: Troubleshooting DAV-HDX265 no power

                                    It looks like you need to have 3.1v on the SD line, 0v means error. The DC-DET line should have 3.3 volts. Check the voltage across the speaker terminals on all outputs.
                                    Last edited by R_J; 09-15-2019, 10:12 PM.

                                    Comment


                                      #19
                                      Re: Troubleshooting DAV-HDX265 no power

                                      Hi! Finally got some more time to look at this.

                                      >> Check the voltage across the speaker terminals on all outputs.

                                      Hmm, no DC voltage on any of the speaker outputs.

                                      >> you need to have 3.1v on the SD line, 0v means error

                                      Thanks, that makes sense now. I was thinking 3v would indicate the error condition there.

                                      To see what would happen, with the resistors after each amp chip pin 4 removed, I put E+4V into this SD line and the "PROTECTOR PUSH POWER" (SD DETECT) message goes away, and the unit even turns on. Re-checked all speaker outputs, but still no voltage on any of them (something like 0.05vdc), regardless of the Volume setting. I hooked a test speaker to several and input an auxilliary audio source, but no sound ever comes out. The amp chips do start warming up (I have the big heatsink off right now).
                                      I am able to press the Function button and cycle through things, but DVD (or pressing the Eject button) goes into an endless "PLEASE WAIT." Not sure what that means... I never hear any motors or anything in the DVD player attempt to move.

                                      >> The DC-DET line should have 3.3

                                      I do see 3.3v there, so guessing that is good.

                                      I'm guessing the first step is getting the amp chips to output 3v on the SD line first, but does the above test of bypassing the SD error line resulting in no audio output & DVD "PLEASE WAIT" indicate additional damage? Or might everything clear up once the SD issue is resolved?

                                      Thanks for all your help!

                                      Comment

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