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1084S-P LOPT+HOT replace

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  • 1084S-P LOPT+HOT replace

    Hi guys,

    My Philips 1084S has bitten the dust after a few months of disuse. The symptom is a high pitch whine that gradually lowers when you turn off the power. From thread searching I can see that this is usually the LOPT and/or the HOT. I've got it apart and I've not found any dry solder joints, ruling out that possibility of an easy fix!

    My problem is: I can easily identify the LOPT, but I'm not sure what the HOT is supposed to look like... can anyone help?
    The humble amiga - A1200, 4GB HDD, 802.11b wireless, 4MB trapdoor RAM card.

  • #2
    The hot is the Horizontal Output Transistor, which looks like THIS.
    Been trying to get corage to open one of mine 1084s-P1 with the exact same simptoms as yours to try to fix it, do you know the exact replacement flyback part number?
    A1200 ACA1233n || A1000/A2000/A500/A500+/A600|| + 8,16,32 bit systems :cool:

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    • #3
      Hi there

      Not sure how helpful this is, and hopefully someone will correct me if I'm wrong, but this is a picture of what I thought was the horizontal output transistor on my Philips CM8833-MkII:


      The component was labelled "H O/P" on my monitor's board, and as you can see it is attached to a large heatsink and situated right next to the flyback transformer.

      Comment


      • #4
        Thanks for the help guys, I was 80% sure that "H O/P" was the right component, so just thought I'd double check.

        Tonight I can desolder these parts and find out the part numbers, then set about getting replacements.
        The humble amiga - A1200, 4GB HDD, 802.11b wireless, 4MB trapdoor RAM card.

        Comment


        • #5
          Don't mind trying to find a 1:1 replacement transistor.

          Get the best nowadays equivalent (prefer one with internal crowbar diode) and use it. Buy LOTS (OK, five parts is enough!) of it as you may toast the transistor if you don't swap the LOPT first.

          The flyback normally suicides, but some times it takes the transistor with it.

          Check for any burnt resistors in the vicinity also and replace those with the exact same value (in Ohms) and power dissipation (Watts).
          David Bradley made Ctrl+Alt+Del, Gates turn it mandatory
          16 Amigas at home :D
          3x C= 64 :smile:
          1 VIC-20 :smile:
          8 PC (argh) :thumbsdown: at least one is an AROS/Amithlon unit

          Comment


          • #6
            Originally posted by rkauer View Post
            Don't mind trying to find a 1:1 replacement transistor.

            Get the best nowadays equivalent (prefer one with internal crowbar diode) and use it. Buy LOTS (OK, five parts is enough!) of it as you may toast the transistor if you don't swap the LOPT first.
            I was going to swap both simultaneously, just to be on the safe side.

            Originally posted by rkauer View Post
            The flyback normally suicides, but some times it takes the transistor with it.

            Check for any burnt resistors in the vicinity also and replace those with the exact same value (in Ohms) and power dissipation (Watts).
            The rest of the components appear OK, at least superficially. There are no scorch marks on or around any of them, nor on the underside of the PCB.
            The humble amiga - A1200, 4GB HDD, 802.11b wireless, 4MB trapdoor RAM card.

            Comment


            • #7
              Just don't panic when first switch the monitor on after the repair: the potentiometers on the back of the flyback are always set to zero (null, nothing, step none, you get the picture) and must be slowly turned to half-way path to the maximum.

              Start with the bright control, then focus.
              David Bradley made Ctrl+Alt+Del, Gates turn it mandatory
              16 Amigas at home :D
              3x C= 64 :smile:
              1 VIC-20 :smile:
              8 PC (argh) :thumbsdown: at least one is an AROS/Amithlon unit

              Comment


              • #8
                Thanks for the advice!

                What's a good online vendor for these kinds of parts?
                The humble amiga - A1200, 4GB HDD, 802.11b wireless, 4MB trapdoor RAM card.

                Comment


                • #9
                  For the LOPT, HR itself (or any near electronic parts shop). For the transistor even evilbay.
                  David Bradley made Ctrl+Alt+Del, Gates turn it mandatory
                  16 Amigas at home :D
                  3x C= 64 :smile:
                  1 VIC-20 :smile:
                  8 PC (argh) :thumbsdown: at least one is an AROS/Amithlon unit

                  Comment


                  • #10
                    I've removed the old flyback and HOT, now flyback says part nº: E39144 AT2079 37591 TY, is the replacement the HR 7506 correct?
                    A1200 ACA1233n || A1000/A2000/A500/A500+/A600|| + 8,16,32 bit systems :cool:

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                    • #11
                      For what I could read, yes.
                      David Bradley made Ctrl+Alt+Del, Gates turn it mandatory
                      16 Amigas at home :D
                      3x C= 64 :smile:
                      1 VIC-20 :smile:
                      8 PC (argh) :thumbsdown: at least one is an AROS/Amithlon unit

                      Comment


                      • #12
                        The part replacement for the flyback of my 1084s-P1 is HR 7533 after all (original AT2079-37591), just reserved one locally for 20€ . It seems that commodore used all sort of available parts at time and resulting in inumerous combinations for the 1084s series of monitors .
                        A1200 ACA1233n || A1000/A2000/A500/A500+/A600|| + 8,16,32 bit systems :cool:

                        Comment


                        • #13
                          Time for update, flyback replaced, HOT replaced, monitor now as excelent image , sharp image and strong colors.

                          Now only remais some adjustements to the image, it shows kind of rotated to the left by 1' (last image), were can i adjust this??
                          Attached Files
                          A1200 ACA1233n || A1000/A2000/A500/A500+/A600|| + 8,16,32 bit systems :cool:

                          Comment


                          • #14
                            Well, mine's fixed too! HR never wrote back to me about the flyback, so I ordered my replacement through Donberg in Ireland. They were very quick and helpful.

                            Some pictures:

                            The old flyback and the spare transistor.


                            Close up showing the model number on the flyback.


                            Make and model of the tube. PHILIPS M34EAQ01X


                            Flyback's 9 solder points


                            Flyback installed, alongside new horizontal output transistor, just right of the yellow rectangular thing, and clipped to the heatsink.


                            The picture is brighter and sharper than ever. Thanks for your help, AmiBayers!

                            JLPedro, the little plastic sliders around the neck of the tube adjust various aspects of the image, including rotation. They're very hard to move though, usually glued in place at the factory after calibration.
                            The humble amiga - A1200, 4GB HDD, 802.11b wireless, 4MB trapdoor RAM card.

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                            • #15
                              Good topic! PM Sent SquallStrife.

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