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Thread: 1084S-P LOPT+HOT replace

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    Default 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?

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    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?
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    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.

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    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.

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    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).
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    Quote 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.

    Quote 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.
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    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.
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    Thanks for the advice!

    What's a good online vendor for these kinds of parts?
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    For the LOPT, HR itself (or any near electronic parts shop). For the transistor even evilbay.
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    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

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