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Help Identifying a Component

Discussion in 'Datasheets, Manuals and Component Identification' started by RogerS7642, Sep 1, 2020.

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  1. RogerS7642

    RogerS7642

    3
    0
    Sep 1, 2020
    I wonder if someone can help. I need to replace this component from an amplifier that dates back to around 1960. I assume that it is a resistor and when I put an ohmmeter on it I get a wide range of values but readings of about 1-4 megohms are the most common. Although the end has broken off it, very little is missing, I believe that it has only three color bands, white, yellow and silver.
     

    Attached Files:

  2. ChosunOne

    ChosunOne

    392
    106
    Jun 20, 2010
    Assuming it has a common value, I think it has to be a 390KΩ resistor, +/- 20%. Can't really tell its size without something for scale, but I'd guess it's 1/4 Watt. I'd replace it with 390KΩ +/-10%(gold band instead of silver), 1/2 Watt (slightly larger) to be sure. Resistors are cheap and overkill doesn't cost much.
     
  3. ramussons

    ramussons

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    71
    Jun 10, 2014
    A photo of the PCB and the location of the component will give us some idea of what it could be.

    It could be a Diode, Capacitor.......
     
  4. shrtrnd

    shrtrnd

    3,796
    503
    Jan 15, 2010
    I second ChosunOne's opinion.
    My additional input is that resistors don't burn-up by themselves.
    I'd be back-tracing that circuit and find-out what other component in there is damaged, that caused that resistor to overheat,
    otherwise you're going to be looking to replace your replaced resistor again in the near future.
    Good luck.
     
  5. RogerS7642

    RogerS7642

    3
    0
    Sep 1, 2020
    The resistor (assuming that is what it is) was on the back side of the circuit board. I don't think it burned. I think it failed because of physical damage. But this amplifier has not worked for the last 50+ years. I know that it hasn't been powered up in that time. One of he transistors was physically damaged. The rest of the board looks OK but who knows what deterioration a half-century will cause?
     
  6. kpatz

    kpatz

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    84
    Feb 24, 2014
    At that age especially unused it's probably in need of new electrolytic capacitors as well.

    Being from 1960 you may be able to find a schematic or service manual online. That would help identify the component, its value, and its purpose.
     
  7. RogerS7642

    RogerS7642

    3
    0
    Sep 1, 2020
    There is no manufacturer name to be seen on the board; so I drew a schematic myself (attached). Any further assistance will be much appreciated.
     

    Attached Files:

  8. bertus

    bertus Moderator

    1,489
    590
    Nov 8, 2019
    Hello,

    Looking at the schematic, it is a feedback resistor.
    The value of 390k suggested by @ChosunOne could well be correct.

    Bertus
     
  9. ChosunOne

    ChosunOne

    392
    106
    Jun 20, 2010
    Correction: My earlier post was off the top of my head and in the wee hours of the morning, and I didn't think to check before posting. Don't know what I was thinking, but a silver band on the end of your disintegrating resistor indicates a +/- 10% tolerance, not 20%; and a gold band would be a +/-5% tolerance. I know the other guys must have caught that; I guess they were just being nice, not to embarrass me. :oops:
     
  10. bertus

    bertus Moderator

    1,489
    590
    Nov 8, 2019
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