Fixing a TV

[ifrgtmyname]

Hi there, I haven't posted for a while so I'd like to start by congratulating the AM crew for the sites success!

Anyho, My sister came home from uni the other day telling me the TV had blown up- so tonight I decided to take it apart and see what was going on. From what I can see a fuse has blown leaving a black mark around it. The fuse reads T3,1.5A which I now understand to mean this is a T type fuse rated 3.15A. If that is right, then would this replacement fuse from rapid do?

http://www.rapidonline.com/Electrical-Power/Fuses-Circuit-Breakers/European-Fuses/Time-lag-subminiature-fuses/73587/kw/3.15A

Because this is for my sister and not myself I thought it would be wise to check this was a safe repair (if it does work at all). The original fuse was a cartridge shape. I should probably also mention that being in the UK our plug sockets operate at 240V.

Thanks

Elliot

P.S. here are some pictures:

http://img90.imageshack.us/my.php?image=p1020150rz5.jpg

http://img49.imageshack.us/my.php?image=p1020153kd0.jpg

http://img49.imageshack.us/my.php?image=p1020152xy3.jpg

[JumpFalcon]

Remember to discharge the TV first. A 10,000V charge can be stored in the TV even when unplugged. I say this because I know someone in a wheelchair after the shock threw him against a wall.

Not to sound harsh or disparage you, but if you think that the RMS voltage of UK mains is 240V (not 230V) then maybe you shouldn't be messing around with TVs.

[bustinthejustin]

Yeah. It's cause of all the capacitors and stuff in them. This is also why you're not supposed to open PSUs. Just be careful and don't touch any capacitors. Hey Falcon, how do you suggest he discharges the TV?

[JumpFalcon]

Yeah. It's cause of all the capacitors and stuff in them. This is also why you're not supposed to open PSUs. Just be careful and don't touch any capacitors. Hey Falcon, how do you suggest he discharges the TV?

Depends on the type and model. Some brands have special points made for discharging, as well as things called bleeder resistors to discharge the high voltage stored in the capacitors (but these are prone to failure after just a couple of years).

If you don't know the insides of TVs well (they are super complicated), I would take it to a repair shop for discharging.

If you really want to try it, tell me the make and model and I can help you a little before you do so. Making sure you're safe is the most important thing here.

[Max_Kreeger]

lol my TV's died as well. It turns on but the screen stays black. We got it fixed once but it happened again. Basically its cheaper to get a new one. - But don't Caps only store their charge for a few seconds after they're unplugged from the PSU ?

[PspKicks316]

lol my TV's died as well. It turns on but the screen stays black. We got it fixed once but it happened again. Basically its cheaper to get a new one. - But don't Caps only store their charge for a few seconds after they're unplugged from the PSU ?

It all depends. I had a cheapo camera you buy for like $5, and I had opened it up and waited a while before touching anything(took the batteries out), and the cap hadn't discharged yet. Even though it was a cheapo camera, it gave my hand quite a buzz from that.

[bustinthejustin]

Caps could stay charged for up to a week, maybe more.

[PhenomenalDesigns]

Just wear gloves and dont touch any metal contacts

[ifrgtmyname]

Thanks for all the comments people

Remember to discharge the TV first. A 10,000V charge can be stored in the TV even when unplugged. I say this because I know someone in a wheelchair after the shock threw him against a wall.

Not to sound harsh or disparage you, but if you think that the RMS voltage of UK mains is 240V (not 230V) then maybe you shouldn't be messing around with TVs.

Ok, I shall try to find a shop to discharge the caps thanks for that, it did cross my mind but the TV has been unplugged for a month. After these posts i will be sure to get the Tv discharged properly.

As for your comment on 240V, do you live in the UK? If so then I recommend you put a multimeter into the nearest socket and check your readings. Despite the fact that the sockets are now rated at 230V, the vast majority of them still put out 240V.

[JumpFalcon]

Thanks for all the comments people

Ok, I shall try to find a shop to discharge the caps thanks for that, it did cross my mind but the TV has been unplugged for a month. After these posts i will be sure to get the Tv discharged properly.

As for your comment on 240V, do you live in the UK? If so then I recommend you put a multimeter into the nearest socket and check your readings. Despite the fact that the sockets are now rated at 230V, the vast majority of them still put out 240V.

Multimeter to the socket... no thanks. They output up to 253V actually, but the root mean squared voltage is 230V if it abides to the European spec, it also dips to around 216V as well. The problem is many supply systems aren't updated hence your reading.

As for capacitors in TVs, they can store the charge for years.

[ifrgtmyname]

Multimeter to the socket... no thanks. They output up to 253V actually, but the root mean squared voltage is 230V if it abides to the European spec, it also dips to around 216V as well. The problem is many supply systems aren't updated hence your reading.

As for capacitors in TVs, they can store the charge for years.

Whilst I appreciate your advice on capacitors. From this post onwards I am not going to argue over 10V

The socket output in my house is 240V. That is why I said that the sockets operate at 240V. There is no harm in putting a multimeter in the socket unless you decide to touch the metal bits in which case, not to sound harsh or disparage you, but you shouldn't be giving advice on this topic.

Now moving away from the +-10V argument will someone please answer the question that this fuse is a suitable replacement?

http://www.rapidonline.com/Electrical-Power/Fuses-Circuit-Breakers/European-Fuses/Time-lag-subminiature-fuses/73587/kw/3.15A

Thanks

[JumpFalcon]

Is there any more info on the fuse you want to replace, like p.d. rating or breaking capacity? It is most likely that the fuse you posted will be fine, but a high breaking capacity might be needed for a TV.

[ifrgtmyname]

Is there any more info on the fuse you want to replace, like p.d. rating or breaking capacity? It is most likely that the fuse you posted will be fine, but a high breaking capacity might be needed for a TV.

There doesn't seam to be, no. It is advertised as a European fuse and so is 'rated at 250V AC'. I don't know anything about the breaking capacity though. Ah well if it doesn't work it doesn't work. I am also happy to hear that my Dad will ask his electrician-type friend if he can discharge the caps- which would be useful.

About the post on wear gloves and don't touch the metal, would that work? I mean of course it would with small discharges but with up to 10000V?

Thanks again

[JumpFalcon]

There doesn't seam to be, no. It is advertised as a European fuse and so is 'rated at 250V AC'. I don't know anything about the breaking capacity though. Ah well if it doesn't work it doesn't work. I am also happy to hear that my Dad will ask his electrician-type friend if he can discharge the caps- which would be useful.

About the post on wear gloves and don't touch the metal, would that work? I mean of course it would with small discharges but with up to 10000V?

Thanks again

I'm not sure about whether it would "jump" or not, I know it can at high voltages, but how high I don't know. Rubber gloves should be fine, once it's fully discharged and unplugged it should be safe to touch, but you can never be too careful.

And about the fuse, you're right, if it doesn't work, it doesn't work.

[PhenomenalDesigns]

About the post on wear gloves and don't touch the metal, would that work? I mean of course it would with small discharges but with up to 10000V?

Yeah I do it all the time, ive had to open up my wall sockets for many reasons

The metal, dont touch them too much just incase, you never know

And yes electricity can jump, but thats at about 10000, the caps in tvs are actually like 400v

If it had 10000 the PCB traces wont be able to tolerate that voltage

Oh yeah do this also to make sure

Get a screw driver (insulated handle) and make it touch the contacts at the same time on the capacitors. It will discharge them instantly



(Also DONT wear an anti static wriststrap, since if by any chance you touch a high voltage point, you will act as a  link to ground)

[Alien_X]

Yeah I do it all the time, ive had to open up my wall sockets for many reasons

The metal, dont touch them too much just incase, you never know

And yes electricity can jump, but thats at about 10000, the caps in tvs are actually like 400v

If it had 10000 the PCB traces wont be able to tolerate that voltage

Oh yeah do this also to make sure

Get a screw driver (insulated handle) and make it touch the contacts at the same time on the capacitors. It will discharge them instantly



(Also DONT wear an anti static wriststrap, since if by any chance you touch a high voltage point, you will act as a  link to ground)

PCB traces can handle high voltages like that fine, it is amperages which the guidelines are written for.
And electricity can arc at voltage lower than 10 000.

[802Chives]

I cannot stress safety anymore than what has been said before....but I will try: The tube television Power Supply may be the most dangerous piece of consumer electronix in you house.  A microwave may be a close second.  There are hundreds of volts being generated, which may not kill you but can definately lead to adverse health effects down the road.

So please think long and hard before you open up your TV.  There is one rule of working with electronix that sticks out in my head, and that is the one hand rule.  Only use one hand to work on electronix as so you don't create a direct path for electricity through your heart.  As far as the wrist strap is concerned, I might recommend you use that on the same hand you are working with as then the path will be limited from your finger to ur wrist.  wear rubber sole shoes.

(the wrist strap is a tricky one,  without one you still may create a path for the discharge, there is the possiblity that the voltage potential will be so great that the path will conduct through you feet to the structure you are in.  So it is an iffy thing whether or not you will be isolated from the discharge without the wrist strap so in this case I would side with wearing one as a burn on hand will hurt a lot less then a burn on your internal organs)

I think that replacing a fuse will not likely be the only problem with this TV.  There is usually a reason for a fuse blowing, and the fuse is not there to be replaced in order to fix a problem, it is there to stop a fire from occuring in whatever failed in the first place.  With the way tube TVs are being made 99% of the time it will cost more to fix then to replace the TV.  You dont see many TV repair shops anymore for that reason.

As someone who works with electricity everyday I cannot recommend anyone ever open a television or a microwave, the potential consequences just aren't worth the risks.