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Crystaleyes
Crystaleyes
Badcaps Veteran
Last Activity: 02-23-2026, 05:11 AM
Joined: 09-18-2021
Location: Rio
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  • Crystaleyes
    replied to Denon AVR E400 - Very unwell
    in Troubleshooting Audio Equipment
    That would have been ideal only the unit was switching off after 3 seconds.


    Anyway.. There has been an unforeseen turn of events.

    Last Friday, after spending several hours checking the circuitry and cleaning away the gunk from the IC pins and other components, I left the board exposed on top of the open Denon receiver and being the weekend, got on with other things.
    Fast forward to Sunday and whilst retrieving a box from the top shelf, a large picture frame fell and hit the Denon board.. 🤦‍♂️
    In the process, it knocked off a few capacitors...
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    Last edited by Crystaleyes; 12-01-2025, 07:16 PM.

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    • Crystaleyes
      replied to Denon AVR E400 - Very unwell
      in Troubleshooting Audio Equipment
      Thanks.

      Sounds like a good idea. I did notice that a few of the through holes were slightly oxidised.

      Onwards and upwards.
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      • Crystaleyes
        replied to Denon AVR E400 - Very unwell
        in Troubleshooting Audio Equipment
        Soldered a jumper and now the unit starts. The relay clicks with the display appearing, however it now switches off after a few seconds and gives the flashing red LED.

        For some reason, I suspect the SMPS board 🤔


        Need to do more research now.



        Edit.

        Someone said that switching the On/Off button twice made a difference.. and it actually did. Before, even whilst performing the factory reset option the unit would crash. Now, I can perform the reset without crashing, although once the buttons are released the unit crashes again....
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        Last edited by Crystaleyes; 11-26-2025, 12:30 PM.

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        • Crystaleyes
          replied to Denon AVR E400 - Very unwell
          in Troubleshooting Audio Equipment
          After a nights sleep, I've managed to backtrace part of the way, which is good. It means I'll get there... Eventually

          This is the first Denon manual I've had a look at and it's taken a while to get used to, however, correct me if I'm wrong but it seems that the 'MAIN POWER' line from the CPU, is direct to the SMPS board other than passing through a single inductor. That said, it should then be a clear path back to 'MAIN POWER' pin 127 of the CPU. But it's not.

          Have to work now but shall keep going

          Edit.

          Couldn't resist another quick look and...
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          Last edited by Crystaleyes; 11-26-2025, 07:51 AM.

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          • Crystaleyes
            replied to Denon AVR E400 - Very unwell
            in Troubleshooting Audio Equipment
            Deep diving into the manual, I've arrived at that, 'can't see the wood for the trees' moment so am asking for some help in following the circuitry

            Enclosing the service manual this time...

            The current situation is, that the relay on the SMPS board isn't being activated when the unit finishes it's green flashing LED cycle upon being switched on.

            The on/off switch 'is' sending the 'POWERKEY' (3.3v) signal from the front panel up to pin 9 of U3002 CPU on the HDMI board, however the 'MAIN POWER' signal from CPU pin 127 (and which is needed to turn on the smps...
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            • Crystaleyes
              replied to Denon AVR E400 - Very unwell
              in Troubleshooting Audio Equipment
              An update...

              I found all the different reset and error record code options in the manual but still nothing appeared on the display and no relay action was coming from the receiver.


              ..After looking for relays, there is one which switches on the mains voltage, located on the power supply board, and I think five on the main board (of which at least four seem to be for different input channels).

              Clearly the PS board relay should be activated when the on/off switch is pressed on the front panel... This hasn't been happening.

              So, after waiting...
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              Last edited by Crystaleyes; 11-23-2025, 07:29 PM.

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              • Crystaleyes
                started a topic Denon AVR E400 - Very unwell
                in Troubleshooting Audio Equipment

                Denon AVR E400 - Very unwell

                Hi everyone.

                Hoping that someone here has some experience with the AVR E-Series

                Came across this pristine but poorly unit in a 2nd hand HiFi shop the other day and thought I might learn something in nursing it back to life.

                It had a sticker on it stating, "working but only in one (left or right) channel".
                Speaking with the shop owner, he said that in fact it would occasionally work in both channels but he doesn't do repairs so it was selling 'as is'.

                Anyway, when he went to show me all this, it refused to even start up. When plugged...
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                Last edited by Crystaleyes; 11-23-2025, 12:43 PM.
                • Crystaleyes
                  replied to LCD TV Power Supply Board question
                  in Troubleshooting TVs and Video Sources
                  A quick update.

                  Found a video of some tech with the exact same TV and identical voltages on the PSU output.

                  He also noticed that the BGA chip on the main board had overheated so switched the main board and the TV came back to life. So, have ordered a new board and I'll confirm the result when it arrives.


                  👍
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                  • Crystaleyes
                    replied to LCD TV Power Supply Board question
                    in Troubleshooting TVs and Video Sources
                    The exploded cap was C9877.

                    Looking over the main board, nothing 'looks' out of place and all the electrolytics have been checked for high ESR. The one thing that is clear is that the BGA chip has been running hot and clearly scorched the board through to the other side. Nothing extreme, but the heating is clear.

                    I'm still far from convinced that the PSU board is working properly....
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                    • Crystaleyes
                      replied to LCD TV Power Supply Board question
                      in Troubleshooting TVs and Video Sources
                      In the end, I put a 12v bulb onto the 12v output and sure enough, once mains connected, the lamp lit up.
                      However, the 24v output dropped to 18.1v.

                      Surely this can't be correct?


                      Also, when the PS/On pin is bridged to the Stand-by pin, then the 12v lamp goes off.

                      Surely this is wrong? It's like the stand-by circuit is connected in reverse. When you close the circuit, the TV goes off, open the circuit and it turns on.... ?????


                      As for when I said 'trusted replacement', that is only what the seller stated. This is Brazil....
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                      • Crystaleyes
                        replied to LCD TV Power Supply Board question
                        in Troubleshooting TVs and Video Sources
                        The voltage on the filter caps is 360vdc across the bridge rectifier is 140vdc - The mains AC supply here is 127v.

                        I'll stick a resistor across and see what happens...
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                        • Crystaleyes
                          started a topic LCD TV Power Supply Board question
                          in Troubleshooting TVs and Video Sources

                          LCD TV Power Supply Board question

                          First off,

                          Happy New Year everyone!



                          Someone recently asked me to look at their Philips 42pfl4508g/78 TV which had stopped working.

                          A quick visual check of the PSU revealed a ceramic cap with a hole burnt through it, and that the output voltages were wonky. The 5.2v Standby was only 3.2v. The 24v - 19.1v and the 12v - 11.2v. We found a cheap 'guaranteed working' replacement PSU online, which they bought and installed but it still the TV didn't switch on, and when I went back to test the new PSU board, it showed the same kind of low output voltages....
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                          Last edited by Crystaleyes; 01-01-2025, 09:44 AM.
                          • Crystaleyes
                            replied to Bench PSU question
                            in General Electronics Technical Discussion
                            Thank you for the suggestions. I'll give that output capacitor a go and let you know how it goes. If that works and the voltage stabilises, then I'll give the diode a go too.

                            Nice one!...
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                            • Crystaleyes
                              replied to Bench PSU question
                              in General Electronics Technical Discussion
                              Think I'm just gonna put in some new ones. I have plenty here......
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                              • Crystaleyes
                                replied to Bench PSU question
                                in General Electronics Technical Discussion
                                Giving the socket a quick clean and a close look, nothing jumps out at me.

                                One other thing, while I remember, is that when the voltage is set to zero, and then the amperage is also set to zero. the voltage goes up to around 5 -6 volts. Not sure if that might be a dodgy pot but a quick test of them shows that the voltage pot goes from 1K down to 1.8 ohms and the amperage pot goes from 10k down to just under 4 ohms....
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                                • Crystaleyes
                                  replied to Bench PSU question
                                  in General Electronics Technical Discussion
                                  Hi all. Thank you for all the input. I'm learning how this thing works thanks to you.


                                  So, re-sitting the filter cap worked. At least in the sense that it no longer blows the 3055, and turned out that only 3055 had blown.

                                  One thing that still needs resolving is the output voltage is fluctuating. Quite savagely. The unit goes from zero up to around 42v but the digital display is constantly and rapidly, jumping around. On lower voltages such as 7v it might jump between 0.3v up and down, although up around 40v it is flying around, anywhere within a 2v difference....
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                                  • Crystaleyes
                                    replied to Bench PSU question
                                    in General Electronics Technical Discussion
                                    So do you think there are any minor modifications which could be made to improve this PSU?...
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                                    • Crystaleyes
                                      replied to Bench PSU question
                                      in General Electronics Technical Discussion
                                      I think I might have found the problem.

                                      As mentioned, this is something I last messed with several years ago and only came off the shelf as I'm having a total revamp in my little overcrowded workspace. In fact, I posted here before even taking a renewed look, as I've just been putting up shelves and sorting boxes. I thought there might be a design flaw which someone might spot?

                                      Anyway, just now I went to actually take some voltages and immediately saw that one of the two main filter caps which I installed maybe ten years ago, was ever so slightly touching the wire connecting...
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                                      • Crystaleyes
                                        replied to Bench PSU question
                                        in General Electronics Technical Discussion
                                        Here is the original list I made of the board components, before any changes.

                                        R1 1R
                                        R2 1R
                                        R3 1k8
                                        R4 4k7
                                        R5 4k7
                                        R6 1K5
                                        R7 3k9
                                        R8 4k7
                                        R9 200R
                                        R10 18k

                                        Q1 BC 547

                                        CI 1 LM 7805
                                        CI 2 LM 7905
                                        CI 3 CA 747CE

                                        C1 1000µF 25V
                                        C2 1000µF 25V
                                        C3 2200µF 40V
                                        C4 2200µF 40V
                                        C5 Not used
                                        C6 472 Ceramic
                                        C7 22µF 25V
                                        C8 22µF 25V

                                        D1 1N4006
                                        D3 1N4006
                                        D4 1N4006
                                        D5 1N4006
                                        D6 1N4006
                                        D7 1N4006
                                        D8 1N4006
                                        D9 1N4148...
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                                        Last edited by Crystaleyes; 11-15-2024, 06:05 AM.

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                                        • Crystaleyes
                                          replied to Bench PSU question
                                          in General Electronics Technical Discussion
                                          This is absolutely possible.
                                          In that photo from when it was bought, it certainly appears that the BC547 has been re-soldered, so it is also either not original or was pulled for some reason? Looking at the datasheet the base collector max is 50v... Perhaps I should try with a 546?
                                          I also have some 3773's here....
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                                          Last edited by Crystaleyes; 11-14-2024, 03:54 PM.

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