Purpose of fuse in televlision

I took apart the television I've posted about and there is a fuse on the power supply board and it's blown. It was blown (and the home circuit breaker was tripped at the same time it iseems) when a helpful neighbor plugged the 110v tv straight into 220.

What is the purpose of the fuse: To keep a short circuit in the power supply (or other part of the tv) from pulling too much current, melting the wire's insulation, and starting a fire?

Or the opposite, to protect the TV from surges.

It will be hard to find another fuse. It's a small size ceramic fuse. I can post the size after I f ind a lamp and a magnifying glass, but it's probably 2 or 3 amps, right? (Are all ceramic fuses slo-blo?)

If the purpose of the fuse is only to protect the tv, I'm willing to take the risk, wrap the fuse in tinfoil and put it back together.

If it's to avoid a fire, then this is a 110v tv in a 220 volt world, supplied by a step-down transformer of limited amperage. 500 watts. (It gives the same wattage for both directions.) Surely even a cold short in the tv when the maxiumum supplied power is I guess about 5 amps would not be anywhere near enough to start a fire.


The other possibility is to wrap the fuse in foil, decide if it works or not, and leave here (where it is too cold for me and too rainy) and come back after I buy the right fuse in a city. What are the odds it will fail in the next 3 week? That requires putting the tv back togehter an extra time, but that's not so bad.

We are 50 miles from nowhere down a rainy winding road.

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It seems to be 8 amps. I didn't think they used them that big, but otoh it's 40amp led screen tv.

We are 50 miles from nowhere down a rainy winding road.

Tomorrow we can make some phone calls trying to find a place closer than

60 miles, but you know as well as I that even if the ad says Electronicsm they probably won't have it, and real reapir stores are few and far between. And I don't want to spend tomorrow night here. I want to fix this and be done.
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In snipped-for-privacy@4ax.com micky snipped-for-privacy@fmguy.com writes: [snip]

About 3 decades (obligatory where does the time go?) ago my large (for the time) Sony tv just died. I took it apart and yes, there was a fuse in the power supply that had blown.

It was a simple automotive type ACG glass fuse, so the next time I was near a car supply place I picked up a set of them.

I figured there was enough of a chance this was a "once off" fuse failure that (aside from my time...) it was worth spending $2.50 or so to check it out.

(Alas, that second fuse blew, too).

Anyway, that might be an option for you. Depending on how the wiring posts are, you might be able to hook up a similar automotive fuse holder and, well, fuse... and see what happens. Probably $10 or so of parts nowadays.

Reply to
danny burstein

You cannot mean 40 amps, surely? Even at only 110 volts that is still quite a powerful heater! 40 inches, perhaps?

Reply to
Mike Coon

micky snipped-for-privacy@fmguy.com wrote

To stop the power supply catching fire if the TV is plugged into 240V and to protect the TV against a surge and to protect against some fool who has chosen to use some fencing wire in the house fuse.

Starting a fire in the power supply.

That too. It doesn't have just one purpose, like most fuses.

No, both types are available.

Wrong. It is what is catching fire that matters.

Or get real radical and order it on ebay or amazon.

Impossible to say when a surge may happen.

But presumably can still get ebay and amazon deliverys.

Reply to
Rod Speed

micky snipped-for-privacy@fmguy.com wrote

You sure it isnt 3 amps ?

That is unusually high for a TV unless its a plasma

Presumably you mean 40 inch.

Reply to
Rod Speed

micky wrote: ==========

** The US, Canada and Japan use 100 or 120 VAC power at 60Hz. So where are YOU ?

Can this 40 inch set happily use 50 Hz power and pick up the local broadcast format ? Has it ever worked there?

.... Phil

Reply to
Phil Allison

To stop your house burning down.

It won't be hard to find another fuse, but you might have to pay for postage.

The fuse will usually blow after something else in the TV has failed. If you bridge the fuse, it will fail harder.

The transformer has limited amperage because if you overload it, it will burn out or catch fire.

Get a proper fuse. Buy two, because the first one will probably blow due to the fault that blew the first one. Use the second after you've fixed that fault.


Reply to
Clifford Heath


** Plenty of homes have burned down due to TV set fires that did not blow the fuse.
** Huh ?

** Most have a thermal fuse inside them.

** You did see how the "110V" set had been somehow connected to "220V" ??

Massive over voltage on the PSU, electros become voltage clamps and MOSFETs go phufft.

...... Phil

Reply to
Phil Allison

The question is, how many have *not* burnt down due to a TV set fire that didn't happen because the fuse blew? No protection is perfect.

A fuse in your TV isn't going to stop a meteorite hitting your house either.

Hopefully. Not a good idea to rely on it, as he seemed to suggest he would.

Yep, exactly why I told him not to hope a replacement fuse would fix it. Told him to buy two fuses because he probably won't listen :)

Reply to
Clifford Heath

Clifford the Chirping Cricket wrote: ==============================

** No it isn't.

You reply was WRONG.

** Too many hypothetical negatives for me....
** That POS takes the "straw man" fallacy to a whole new height.
** My god, you are one desperate f****ng wanker.

Blowing the shit out of a SMPSU with double supply voltage not a FAULT.

Maybe you think crashing your car into a tree is a "breakdown" ??

...... Phil

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Phil Allison

This seems very important. If there is one that's shorted, it will just blow the fuse over and over, and if I've bypassed the fuse....would that allow enough current to start a fire?

The board has a fee parts that might be a MOV. They are labeled CY101..., TH101..., UA101 and CP101. There is only one of the last two. Are any of these usual abbreviation for a MOV? I've been looking online for a list of abbreviations that includes these, no luck so far, quicker to ask you, Bob (and others).

Retirednoguilt was kind enough to post Power supply on ebay shows a fuse in the photo :

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that looks just like her power supply. --- Surprising since I had found this video of someone repairing the PS on supposedly the same model and the boards look entirely diffferen -- [Insert url here]

I'm the second or third person she's had look at it. It's too big and heavy to take to a shop, so if I bypass the fuse and fail to note a shorted MOV and it gets worse, I think she will just take her loss and buy one.

References to previous thread. The TV has HDMI input (3 interfaces!), but when she lived in Baltimore she was streaming from Amazon, and I think that was her current plan. Although I don't understand how. The manual says "INPUT — Repeatedly press to change the source you are viewing (ANT/CABLE, VIDEO 1, VIDEO 2, ColorStream HD1, ColorStream HD2, HDMI 1, HDMI 2, HDMI 3, PC)."

Colorstream is their name for separate red, blue, whatever color input. Component! That's it. She can't use that.

Video1 AND 2 are composite, she can't use that.

PC IN — For use when connecting a personal computer. When she lived in Baltimore her PC was in another room and I don't think there was a wire connecting them. I've written her son to try to find out what she is talking about.

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** Plus itself too - MOVs explode and shatter.

** No. But would trip your breaker.

...... Phil

Reply to
Phil Allison

(what url did you forget to insert?!)

Did you not read the warning above the fuse on that PCB? "CAUTION: For continued protection against risk of fire replace only with same type and rating of fuse". I don't think it could be any clearer.

Out of interest, is it usual in the US to spec a 240V fuse for use with a 120V supply?

Reply to
Jeff Layman

Ok, guys, I jumpered the fuse holder with a store-bought 10" jumper wire and got a big spark (even before I tried to turn the tv on. I guess I should have anticipated that.)

I thought that was bad until I thought, Well, it uses almost 8 amps and maybe the alligator clips didn't make a good connection.

So used all three jumper wires and this time no spark, just smoke. :-)

From one of the diodes, based on the brown spot next to it and the swollen diode.

Plus the alligator clips at one end of two of the jumper wires fell off!

So now it's on to a new board.

The board is discontinued of course, but there are lots for sale at various places, all about 40 dollars. Whether they are new, "reconditioned" or used, it's okay by me.

The part number is Toshiba PK101V0830I

But what would be great is to find the 220v version of this. So how would I find what the part number is for the 220 volt version of this.

I wrote Toshiba to ask what the partnumber would be for 220v, but I think I wrote Toshiba USA. I can call Toshiba in the US Monday at

8AM. Will they know or should I call some European repairman? I haven't found a tech support page for anywhere in Europe yet. It looks like I have but then the page is about all of Toshiba, not just tvs, not just consumer goods,

Would Toshiba use the same tv model# 40RV525U for its 220volt model? I doubt it, and I can't guess what it would be.

What should I do next? (Helpful answers only, please.)

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In the US fuses for the plug in devices like lamps and TV sets are usually rated for 250 volts. It is fine to use a fuse rated for 250 volts on the 120 volt devices. Most of the house wiring is for 120 volts for the common plug in wall sockets.

There are some fuses rated for around 25 volts (forget the exect voltage) that are made to use in the older cars that operate on 12 volts and maybe 24 volts DC.

The reason for a voltage rating on a fuse is that if a higher voltage is used it may arc over and not actually cout off the power. A fuse rated for 10 amps will open at around 10 amps no matter what the voltage is as long as it is low enough not to arc over.

Reply to
Ralph Mowery

Who knows! With all the radiation I've gotten ever since I used that off-brand fuse, I can't tell my right hand from my right hand.

No. Warnings are for grown-ups.

Most fuses go up to 250, don't they?

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I was going to find the url before posting. Failing that I tried just now.

Someone messed with my Firefox and made Bing the default search engine!! I sure didn't do that.

So I thought if I went back to google I'd find it. It was the second or third hit when I first looked, searching on the TV model number. Now I can't find it at all. I thought it int eresting becaue the board didn't look at all like the one in the ebay ad, and maybe someone wrote him or he noticed he had the wrong model number and he changed it, so I can't find it. Who knows? It was the wrong video anyhow.

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