Goodmans LD3265

Discussion in 'General Electronics Chat' started by tom66, Jul 26, 2011.

  1. tom66

    Thread Starter Senior Member

    May 9, 2009
    2,613
    214
    Got this 32" LCD TV in for cheap.

    The symptoms sound like bad caps but it doesn't seem like them as none are visibly bulging.

    The TV will turn on only sometimes. Once turned on it works perfectly, not a problem in the world. But you will have to wait hours if not days before it is ready to work again.

    I performed the soft-start modification, disabling the soft-start FET Q837 connected to pin #8 of the SG2525A. The set worked perfectly for 3 weeks, then died again, with a blinking front LED. I reversed the mod, now we're back to the original problem, it just won't turn on.

    The only thing left for me to do is to buy a new power supply unit for the TV which is around £20. I'd like to avoid doing that if possible because it's kinda like giving up on a difficult puzzle!

    The chassis is a Vestel 17MB22-2. I have the service manual available if anyone wants it. There are schematics included in the service manual.
     
  2. debe

    Well-Known Member

    Sep 21, 2010
    946
    184
    Capacitors can be dried out & faulty they dont have to bulge. Check the circuit of the SMPS there may a resistor to kick start the powersupply. These can give trouble if gone higher in value. Can you post the powersuply circuit.
     
  3. Jotto

    Member

    Apr 1, 2011
    159
    17
    It probably uses a PMPS, look for a 47mf @ 50v volts it should be close the pulse width modulator. It could be a PWM and FET combined. There should also be a few 100mf caps that should be looked at. I wouldn't look at any cap over 1000mf at this point.
     
  4. tom66

    Thread Starter Senior Member

    May 9, 2009
    2,613
    214
    Here is the service manual on eserviceinfo: http://www.eserviceinfo.com/download.php?fileid=56543

    I'm dealing with a Goodmans, but the insides are identical.

    There are quite a few caps around the SG2525A. Would it be worthwhile replacing them? If so, could I use cheap non-low-ESR ones or should I use proper ones?
     
  5. Jotto

    Member

    Apr 1, 2011
    159
    17
    You get what you pay for. I would use good quality caps if you can get them. You want low ESR caps, long life or high temp.
     
  6. tom66

    Thread Starter Senior Member

    May 9, 2009
    2,613
    214
    I recap secondaries always with high quality ones. I recap'd my LG 42" with Rubycon YXF, my 19" monitor with UCC KZG and my ethernet adapters with Panasonic and Nichicon low-ESR.

    I found a power supply for £10, so I bought it. I gave in :p. I've been working on this bugger for weeks now - not been easy.
     
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