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Power Supply Unit - Sony VCR

Discussion in 'Home Cinema, Hi-Fi and Gadgets' started by Joshie, Jan 8, 2003.

  1. Joshie
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    Joshie Member

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    [Jan 8, 2003]
    Does anyone know who'd be able to repair a PSU from a Sony VCR without it costing more than a new VCR. The unit has been removed from the VCR.

    Perhaps Dan (Toasty) is the man?
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  3. Jon
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    Jon Member

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    [Jan 8, 2003]
    Have a search around on the web using the model number of the VCR, there are usually sites that will tell you which parts are prone to going etc and sell kits of these parts.

    Normally a failed PSU will be caused by capacitors going resistive, dry joints, on board fuses blown etc You stand a half decent chance of fixing it just be resoldering any joints that look dodgy.

    Can you see any visible damage, burning etc on the board? Does it smell burnt?

    HTH,

    Jon.
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  4. Joshie
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    Joshie Member

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    [Jan 8, 2003]
    Actually a bit of black dust around the jonts of the 400V 68 uF capacitor - just thought this was general old age but perhaps a replacement may be worth a try. Think even I could attenpt this. I have a soldering iron /ubbthreads/images/graemlins/laugh.gif

    I'm just a layman but the circuit looks fairly simple although I cant see whats under the tin cover (said I was a layman /ubbthreads/images/graemlins/confused.gif)

    Thanks for the advice Jon
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  5. toasty
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    toasty Member

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    [Jan 8, 2003]
    Tend to agree with Jon.
    Judging by the 400v cap it sounds like a switched mode psu, which usually have on board fuses, check these first.
    If anything looks burnt or charred then it probably needs replacing.

    Give the circuit board a quick wash down with the Isoprop alcohol you have left from the MAF cleaning and resolder any joints that don't look shiny.

    I could surely fix it for you, or if it's that important then even build you a replacement.

    I assume it's an expensive video? If it were mine and not too expensive I'd probably just get a new one. (I once spent ages repairing a TV for my parents... a few months later the tube went!!)

    If it's quite old, then chances are something else will fail soon.

    ....but if you want me to take a look, you know my address by now! /ubbthreads/images/graemlins/grin.gif
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  6. Joshie
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    Joshie Member

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    [Jan 8, 2003]
    Thanks Dan,

    I'll have a crack at it. The unit is a Secam one which I bought when I lived in France so I want to try and keep hold of it. It's not that old really in usage terms and the component(PSU) looks so simple seems a shame to bin it.

    If I fail misearbly I'll call you!
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  7. Jon
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    Jon Member

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    [Jan 8, 2003]
    Most likely it is switched mode, if so watch out as they have extremely high voltages present when powered up IIRC ~20-25KV in the inverter stage, trust me, it hurts!! /ubbthreads/images/graemlins/frown.gif If the PSU has been powered up recently make sure all the capacitors are discharged (make sure anyway) by shorting them out, they can bite too as they store charge.

    If it is one of the capacitors then make sure that you put it back in the right way round, this assumes that the cap is an Electrolytic not just a normal polyester, ceramic etc. Reverse polarised electrolytics are really impressive when they go, rather like a firework but they stink the place of fish for days.

    For components try either RS Component, Farnell or Maplin may have them however over the last few years they have been carrying less and less components.

    You would be as well replacing all the elecrolytic (look like little cans and have a polarity stripe down one side)caps as if 1 has gone the rest usually follow.

    You could also try a search for a replacement PSU on EBAY or somewhere like that, i have also found the local tip to be useful at times as most of them have "collectors" for all the elec stuff and they may have a similar model.

    The power supply should be very similar across most models of the same era and make.

    Cheers,

    Jon.
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  8. Joshie
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    Joshie Member

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    [Jan 8, 2003]
    Thanks John, great advice.

    Actually when I took the PSU out of the VCR I used a multimeter to check that the board was completely discharged (remembered the lesson on capacitors during A level physics) - it took ages for the board to loose all of its charge.

    I'll try Maplins first for the components after applying some of Dans logic on cleaning and resoldering the board

    Thanks again
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