Need help identifying SMD's for replacement on HD 4850 repair!

Discussion in 'General Electronics Chat' started by glappe, May 5, 2010.

  1. glappe

    Thread Starter New Member

    May 5, 2010
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    I purchased a burnt HIS IceQ4 HD 4850 video card for dirt cheap to use the cooler on my reference design Visiontek HD 4850 video card (same card diff color). Now I want to try and resurrect the HIS card if possible. So I'm now trying to figure out the SMD component that I need to replace. Can anyone help me identify this chip? I don't understand the codes but I can solder.

    Pictures included. Circled on the red card (Visiontek) in red is the one that blew and I thought the one circled in blue was damaged but after cleaning it looks ok to me. The blue card (HIS) shows the damage.

    [​IMG]
    By glappe at 2010-05-05

    [​IMG]
    By glappe at 2010-05-05

    [​IMG]
    By glappe at 2010-05-05

    [​IMG]
    By glappe at 2010-05-05
     
  2. SgtWookie

    Expert

    Jul 17, 2007
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    The item circled in blue is a ceramic capacitor, likely size 0603 and 0.1uF to 0.33uF in value.

    The item circled in red mark "X02" appears to be a thick-film resistor, and connected to the VIN terminal (1) of the LM317LC regulator. It's intended use is most likely to remove power dissipation requirements from the LM317LC. I haven't seen an "X02" marking before.
    [eta]
    Come to think of it, the "X02" might be a resettable fuse with a 2A rating.
     
    Last edited: May 5, 2010
  3. glappe

    Thread Starter New Member

    May 5, 2010
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    I looked up the "LM317LC" and here is the quoted text with mention to resistors in red. It could be a resistor for the output voltage but what resistor is it? Could this be a fuseable link? According to the diagram pin 1 in the input so I'm guessing this is a resistor to adjust the input voltage?

    [​IMG]
    By glappe at 2010-05-05




    The LM317L is an adjustable three-terminal positive-voltage regulator capable of supplying 100 mA over an output-voltage range of 1.2 V to 32 V. It is exceptionally easy to use and requires only two external resistors to set the output voltage. In addition to higher performance than fixed regulators, this regulator offers full overload protection, available only in integrated circuits. Included on the chip are current-limiting and thermal-overload protection. All overload-protection circuitry remains fully functional even when ADJUSTMENT is disconnected. Normally, no capacitors are needed unless the device is situated far from the input filter capacitors, in which case an input bypass is needed. An optional output capacitor can be added to improve transient response. ADJUSTMENT can be bypassed to achieve very high ripple rejection, which is difficult to achieve with standard three-terminal regulators. In addition to replacing fixed regulators, the LM317L regulator is useful in
     
    Last edited: May 5, 2010
  4. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    Could it be possible that the x02 component is a diode?
    Sometimes you see diodes accross the lm317 for protection.

    [​IMG]

    Bertus
     
  5. BMorse

    Senior Member

    Sep 26, 2009
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    I believe this is the LM317L from Texas Instruments, it is the only one that comes in an 8 pin package, LM317 by National semiconductor is only available in the 4 pin package at the most...

    B. Morse
     
  6. glappe

    Thread Starter New Member

    May 5, 2010
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    Hmmm, I wonder if it is a surface mount fuse?
     
  7. SgtWookie

    Expert

    Jul 17, 2007
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    Brent,
    Have a look at National's datasheet for the LM317L; it is in fact offered in the 8-pin SOT package. However, Glappe's is definitely a TI as you have observed.

    Glappe,
    R811 (between pins 3 and 4) sets the reference current; it's between Vout and ADJ.
    I'm not sure what R812 is doing. Were it R2 in the TI schematic, it would be between ADJ and GND. However, it's not connected that way on the board.

    C808 is probably for stabilizing the voltage on the ADJ pin.

    I can't think of what else the "X02" part might be.
     
  8. glappe

    Thread Starter New Member

    May 5, 2010
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    Thank you all for trying but I guess all that i can do is BEG the manufacturer for the information IF I can get a hold of them.

    Greg
     
  9. BMorse

    Senior Member

    Sep 26, 2009
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    well, since the X02 component does before the Vcc pin, I would think sarge was right in determining it as a fuse, I doubt they would use a resistor to lower the current into the ic rather than just adjusting the output...

    The one thing though about those burnt out components, there was something else that caused those to burn, if not the LM317 itself, it could be whatever that was supplying power to. So the problem may not just lie in those 2 components.

    My .02

    B. Morse
     
  10. glappe

    Thread Starter New Member

    May 5, 2010
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    Your .02 = a lot of sense Sir! Thank you to all.
     
  11. bertus

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  12. SgtWookie

    Expert

    Jul 17, 2007
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    Nice find, Bertus!

    I hadn't seen those new codes yet.
     
  13. glappe

    Thread Starter New Member

    May 5, 2010
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