Sharp LC-42D62U Inverter board

[FlipTV]

Re: Sharp LC-42D62U Inverter board

Sorry but I'm not quite understanding how to read a defective fuse on the mm.

When it beeps and says OL, is it defective or is it good. When I test good fuses it beeps and says OL.

For this fuse it does not beep and gives a reading.

[tom66]

Re: Sharp LC-42D62U Inverter board

When the meter beeps and shows OL, it is considered faulty (I mean the METER is faulty) and must be repaired or replaced, myself, I would only repair a DMM if I had a valid standard to match it against.

[FlipTV]

Re: Sharp LC-42D62U Inverter board

My MM is set to the audio mode where it beeps if there is an Open Line.

When I test it on a good known fuse, it beeps.

Are you referring to another mode that when it beeps, you should consider your MM defective?

[budm]

Re: Sharp LC-42D62U Inverter board

To do quick test for now, put a jumper wire on that fuse and see if the backlights will come on.
Or, set the meter to DC mode and check the to see if it show 24VDC on each end of the fuse with ref to the chassis ground.

[FlipTV]

Re: Sharp LC-42D62U Inverter board

One side of the fuse reads 23.88v and the other side reads 2.4v

I'll grab a jumper wire and solder it tomorrow to see if the back light will come on.

Thanks for your help with everything so far everyone.

[budm]

Re: Sharp LC-42D62U Inverter board

That fuse is bad. What you can do is to solder two wires to each end of the pad and connect the wire to through hole fuse, wrap up the new fuse with tape. I use PICO II fuse for this kind of repair.
You may also want to invest money on a better meter also if you are going to do more repair.

[FlipTV]

Re: Sharp LC-42D62U Inverter board

Whats a decent DMM that will give reliable readings?

[budm]

Re: Sharp LC-42D62U Inverter board

RetiredCaps can really give you good recommendation.

[retiredcaps]

Re: Sharp LC-42D62U Inverter board

Whats a decent DMM that will give reliable readings?

You have a reliable multimeter already (I also have a Fluke 12). When you put the Fluke 12 in continuity mode, it should beep when you short the probes together and show a reading of nearly 0.0. When the probes are apart it should show 0L (open loop, out of range). See snapshot of manual.

Most people have no problems using a multimeter correctly (i.e. where to put the probes). The main problem comes in interpreting the data correctly.

A good fuse should measure less than 1.0 ohms. I always advise people that using continuity is a very poor indicator whether a fuse is good or not. For example, on the Fluke 12, it will beep "continuous" for any reading under 25 ohms (see manual below). The threshold varies greatly between multimeters. Some really cheap multimeters will beep "continuous" for readings less than 1800 ohms!

https://cdn.badcaps-static.com/pdfs/...732f8b7f83.pdf

If a fuse measures 20 ohms, it is bad, but a novice user will be fooled into thinking the fuse is good. 99% of the guides on youtube, websites, people, don't understand this subtle, but very important, concept.

Continuity, is a useful feature, when the user understands the thresholds and when/where to use it. When it comes to measuring fuses, however, use the resistance setting.

PS. If you still think your Fluke 12 is crap or broken, I will happily take it off your hands.

PPS. When reporting your readings, because we can't see what you are doing, you must report the units. Is it 1.0 ohms, 1.0k ohms, 1.0M ohms, etc?

[budm]

Re: Sharp LC-42D62U Inverter board

What confused me is this statement, that is why I rather have retiredcaps expalin to you.
"Sorry but I'm not quite understanding how to read a defective fuse on the mm.

When it beeps and says OL, is it defective or is it good. When I test good fuses it beeps and says OL.

For this fuse it does not beep and gives a reading."
It does not make sense at all:
"When I test good fuses it beeps and says OL."

[tom66]

Re: Sharp LC-42D62U Inverter board

Ah! Perhaps OP is testing with power on?
I remember trying on a borrowed Fluke 179 if a negative voltage was applied to the meter while in the continuity mode it would beep AND show "-OL" (note the minus)...
Perhaps this is what is happening?

[FlipTV]

Re: Sharp LC-42D62U Inverter board

This is what I was doing to test fuses. Please bare with me as I'm on a learning curve right now.

What I was doing to test fuses with the TV powered off was:

Put the MM into Continuity mode where it will beep when you touch the 2 ends of a fuse.

I was testing fuses this way as most of the tutorials online recommend doing this.

So when I put the MM into continuity mode, touch the 2 ends of the fuse, should it beep if it is good??

Maybe I'll post a video when I get home so you can see first hand what I am referring to.

[budm]

Re: Sharp LC-42D62U Inverter board

Let us know with the jumper result.

[FlipTV]

Re: Sharp LC-42D62U Inverter board

On a side note, is there a general rule you must follow when replacing fuses?

The one I will be replacing is 1.5A 76V.

I'm having a hard time finding a PICO ll fuse that has that same rating.

Can I move up on the Voltage without harming components on the board or is it recommended to replace fuses with the same exact rating?

[budm]

Re: Sharp LC-42D62U Inverter board

Higher voltage is OK, not lower.

[tom66]

Re: Sharp LC-42D62U Inverter board

Well, the inverter is 24V rated, so I can't see the harm in using, e.g. a 32V fuse. Most automotive fuses are 32V rated, so you can use those in a pinch.

[FlipTV]

Re: Sharp LC-42D62U Inverter board

Would this fuse work as a replacement?

http://www.digikey.com/product-detai...1CT-ND/2690162

The fuse on the board has this rating next to it.

1.5A 76V

Sorry if it seems like you guys are holding my hand through this. I just want make sure I have a clear understanding of the process.

Once again thank you for all your help with this.

[budm]

Re: Sharp LC-42D62U Inverter board

That is what I use.

[FlipTV]

Re: Sharp LC-42D62U Inverter board

Great!

I'm going to order this and see how everything plays out after replacing it.

I'll post an update once it's installed.

[FlipTV]

Re: Sharp LC-42D62U Inverter board

What wattage soldering iron should I use on the tv boards?

I used to solder mod chips on game systems a years ago,but don't remember what wattage iron should be used.

I'm going to be buying a new iron and wanted to know what kind to get. Are adjustable irons any good?