1. You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
    Dismiss Notice

Galaxy DX 2547-Resister Burning Out

Discussion in 'General CB Services Discussion' started by HerbBE, Dec 3, 2019.

  1. HerbBE

    HerbBE New Member

    Joined:
    Dec 3, 2019
    Messages:
    3
    Likes Received:
    1
    Hi. I hope someone can give me an idea of possible causes for the same resister burning out as soon as the radio is turned on. All other features on the radio seem to work okay, except this constant burned resister in the meter light circuit. I have replaced it twice, so I know it is something besides a defective resister.



    If you can view the attached schematic, the unit receives 12v up to the resister as indicated on the multimeter. I am assuming everything in the system is okay up to this point. J20 takes the power from the resister to the smaller LED board via three wires. L+ on the smaller LED board gets 13.8v(12v) from the orange wire on J408.

    At this point, I am guessing that a transistor or resister on the LED board is pulling/shorting more power than the small 47 OHM 1/8 watt resister R282 can handle. I don't want to start removing transistors/resisters to test them if I am not on the right track.

    Any suggestions? Galaxy DX 2547-Burned-resister.jpg
     

  2. nomadradio

    nomadradio Analog Retentive

    Joined:
    Apr 3, 2005
    Messages:
    3,098
    Likes Received:
    3,079
    Shadetree Mechanic and Robb like this.
  3. Robb

    Robb Yup

    Joined:
    Dec 18, 2008
    Messages:
    11,139
    Likes Received:
    2,876
    Looks like you need to inspect that board carefully and look for a dead short.
    Only way it could fry.
     
    Woody-202 likes this.
  4. OldTech03

    OldTech03 Sr. Member

    Joined:
    Dec 15, 2017
    Messages:
    557
    Likes Received:
    831
    After replacing the resistor does the light come on or does the resistor puff instantly? If it's instantly then clearly as Robb said there is a dead short between the resistor and the bulb.
     
    Woody-202 likes this.
  5. Robb

    Robb Yup

    Joined:
    Dec 18, 2008
    Messages:
    11,139
    Likes Received:
    2,876
    Another thing: why didn't your radio's fuse pop?
    A dead short should have taken the fuse.
    Curious . . .
    Better make sure you have the right sized fuse in the fuse holder too.
     
  6. 2NC995

    2NC995 WDX995 / DAN

    Joined:
    Feb 23, 2008
    Messages:
    765
    Likes Received:
    1,266
    Wouldn’t the resistor be limiting the current (as well as soaking up a lot more than 1/4 watt)?
     
    Robb likes this.
  7. HerbBE

    HerbBE New Member

    Joined:
    Dec 3, 2019
    Messages:
    3
    Likes Received:
    1
    Thanks for the ideas!:)

    Okay. Today I removed the old transistor (R282) and replaced it with a new (tested) 47ohm 1/8 watt resistor. I checked for loose wires, solder bridges, etc--all clear. Multimeter reads 12v at the resister and on the J20 terminals-G to 13.8v. The 8v to ground on the J20 terminals reads 8v.

    This time, I removed the jumper from J408 at the J20 terminal. I then plugged the radio in and the resister didn't burn. Then I pushed the on/off button on, and again the resister didn't burn. So far so good!

    Can I safety assumed that the problem is passed the J20 terminal, and most likely on the LED board? I am pretty sure if I reconnect the J20 and J408 terminals, the resister will blow. What can I test next?
     
  8. 2NC995

    2NC995 WDX995 / DAN

    Joined:
    Feb 23, 2008
    Messages:
    765
    Likes Received:
    1,266
    Sounds to me like you’re on the right path.

    The sub-board being isolated from the rest of the radio is what I would want for finding a short.
     
  9. sunbulls

    sunbulls Sr. Member

    Joined:
    Apr 25, 2017
    Messages:
    457
    Likes Received:
    691
    Did you try removing the bulb before reapplying the terminals? The leads inside the bulb may have welded themselves together. Christmas tree light syndrome.
     
    2NC995 likes this.
  10. Shadetree Mechanic

    Shadetree Mechanic 808 On The North Side of Dover

    Joined:
    Oct 23, 2017
    Messages:
    2,198
    Likes Received:
    2,334
    Is it possible to plug the jumper in backwards? I suppose it only goes in one way. You could unplug all the connectors from the LED board and then plug in J408 and turn it on. If the resistor is ok, plug all the other plugs into the board one at a time and you might find one that pops the resistor. Or you might find that the radio suddenly works correctly. I have "magically" fixed machines at work just by walking up to them. Haha.
    Chris
     
  11. HerbBE

    HerbBE New Member

    Joined:
    Dec 3, 2019
    Messages:
    3
    Likes Received:
    1
    I have tried several incandescent and LED lights. The lights are all okay.
    I even temporarily wired the bulb directly into the J20- J408 jumper. It lights.

    Yes, this is what I was thinking. This meter light seems to be a problem in a few of these Galaxy DX 2547s, and I thought someone figured this out already!!!! I was looking for some short cuts!!!

    I have checked and rechecked, schematics and photographs of the jumpers and all of the boards. I am sure they are in the correct way. I was thinking about unplugging all of them as you pondered, and I will probably try this, but I am concerned about how this will affect other components, even on this same circuit. For example, the circuit may need another circuit to supply v to a transistor to open.
     
    Shadetree Mechanic likes this.
  12. 2NC995

    2NC995 WDX995 / DAN

    Joined:
    Feb 23, 2008
    Messages:
    765
    Likes Received:
    1,266
    Q402 completes the circuit....but if there’s a direct short it would seem like it had to be between J400 and the lamp?
     

Share This Page

  • About Us

    The WorldwideDX Radio Forum was originally established in 2001. We pride ourselves on welcoming Radio Hobby enthusiasts of all types, while offering unbiased, informative, and friendly discussion among the members. We are working every day to make sure our community is the best Radio Hobbyist's site.
  • Like us on Facebook

  • Premium VIP Member

    The management works very hard to make sure the community is running the best software, best designs, and all the other bells and whistles. Care to buy us a beer? We'd really appreciate it!

    Donate to us!