Forum Discussion

Wrace's avatar
Wrace
Explorer
Feb 09, 2014

TV stopped working, fuse blown?

I have this spectra 32" led tv from this thread. I decided not to use it in our trailer and instead put it in our den 2.5 years ago when we purchased it. It gets very little use.
http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/25929033/srt/pa/pging/1/page/1.cfm

A month ago I unplugged the unit from the den and temporarily moved it out to the living room where I plugged it in and it worked fine. The next day I moved it back to the den and plugged it in and it would not work. I confirmed the outlet in the den is hot.

I took the back off it today and spied the fuse shown in the pictures below. You can see the power cord connects right there to the circuit board near the fuse.

I have the following questions I would appreciate some help on.

- Is this fuse blown? I've never seen a fuse like this so I don't know what it should look like or if you can even tell if it's blown by just looking at it.

- I take it this is a solder-in fuse? I'll need to pull the board, de-solder it and solder in a new one?

- Capacitors on this board hold a charge? If so how long until it dissipates? The tv has been unplugged for 3 days.

- Other safety precautions/advice?

Thanks



  • Gdetrailer's avatar
    Gdetrailer
    Explorer III
    Feb 09, 2014
    Wrace wrote:
    Thanks for the replies.

    Gdetrailer wrote:

    I would not simply clip another fuse to this one for "testing", the proper way to test a fuse like this is by using the Ohm setting on a meter.

    You need to make sure the TV is unplugged and set your voltmeter to Ohms. Then place one lead on one side of the fuse and the other on the other side.

    Meter should show 1 or 2 ohms or less depending on the accuracy of the meter.

    If you get no reading at all then the fuse is blown and needs replaced.

    Just checked and the meter shows 2-3 ohms across the fuse.


    Fuse is good, most meters do not do a good job of zeroing out at this low of resistance. Chances are if you put your meter leads together it will measure the same 2-3 ohms.

    The bad news is something else in your power supply has bought the farm...

    Check for any electrolytic capacitors (these are round cylinders which have a metal flat top when good) which may have a bulge in the tops (this would indicate blown caps) and sometimes changing those will bring back a dead power supply if the bad caps didn't do other damage on the way out.

    The bad caps can be changed but you need low ESR types which you won't find at your local Radio shack..

    On edit.. looks like the caps on your power supply are laying down... can't tell by the photos if they have bulged tops..
  • garry1p's avatar
    garry1p
    Explorer
    Feb 09, 2014
    This is an easy project however, if you have never soldered on a PCB circuit board you can damage the board.

    You really need to test the fuse as stated above these type fuses do not blow for no reason.
    This is a ceramic time delay fuse T=time delay 3.15 is the amp rating and 250vac can be safely applied before arcing over. Replace with a ceramic fuse as a glass fuse can explode in this environment.

    To remove & replace the fuse from the bottom of the board.
    1. Use a LOW wattage pencil type soldering iron less than 50W.
    2. Use a solder sucker or solder wick to remove the old solder and clear the holes for the new fuse.
    3. Insert the new fuse and re-solder best is 60/40 but I don't think you can even buy it anymore. Do not hold the iron on the board any longer than necessary.

    All the above is available at Radio Shack at a reasonable price.
  • Wrace's avatar
    Wrace
    Explorer
    Feb 09, 2014
    Thanks for the replies.

    Gdetrailer wrote:

    I would not simply clip another fuse to this one for "testing", the proper way to test a fuse like this is by using the Ohm setting on a meter.

    You need to make sure the TV is unplugged and set your voltmeter to Ohms. Then place one lead on one side of the fuse and the other on the other side.

    Meter should show 1 or 2 ohms or less depending on the accuracy of the meter.

    If you get no reading at all then the fuse is blown and needs replaced.

    Just checked and the meter shows 2-3 ohms across the fuse.
  • wa8yxm's avatar
    wa8yxm
    Explorer III
    Feb 09, 2014
    I cant see enough detail in the photos but I have seen those fuses.

    If you had the board out and can trace the traces odds are one end of that fuse connects to one side of the power inlet.. And nothing else with the possible exception of a small capacitor Replacement is easy if you know how.
  • schneid's avatar
    schneid
    Explorer
    Feb 09, 2014
    I've dealt with two of these. I just de-solder and remove them and then replace them with a fuse holder and a new fuse. What is strange is you observed nothing when it happened. I knew exactly what DW did when mine blew. Might not be the fuse but that is easily tested.
  • Gdetrailer's avatar
    Gdetrailer
    Explorer III
    Feb 09, 2014
    That is a sand fuse These have a different characteristic than a open glass type), you would want to replace with the same style.

    I would not simply clip another fuse to this one for "testing", the proper way to test a fuse like this is by using the Ohm setting on a meter.

    You need to make sure the TV is unplugged and set your voltmeter to Ohms. Then place one lead on one side of the fuse and the other on the other side.

    Meter should show 1 or 2 ohms or less depending on the accuracy of the meter.

    If you get no reading at all then the fuse is blown and needs replaced.

    To replace the fuse I would suggest removing the old fuse by unsoldering it (the end caps are not holders but are welded to the fuse) and then soldering the new fuse in that place...
  • robsouth's avatar
    robsouth
    Explorer II
    Feb 09, 2014
    If you find a new fuse, just jumper clip in place to see if that is the problem, if so, then replace by whatever method you are comfortable with. From looking at replacement fuses on Amazon, Ebay, etc, the fuse does not appear to be a solder in place fuse, but a common fuse that fits into the soldered in place holders at each end of the fuse. Check that out.
  • MrWizard's avatar
    MrWizard
    Moderator
    Feb 09, 2014
    looks like main input power fuse
    yes its soldered in
    these caps have probably already lost most power
    spreading it into the DC circuits when you tried to turn it on
    this NOT the same as sticking your hand into the back of an OLD color CRT hi-voltage set up

    depending on soldering skills, you can just solder new fuse piggyback on the old one
    removing old fuse might need some solder sucker tool or ribbon

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